Excavations and Surveys at the Law Ting Holm, Tingwall, Shetland: An Iron Age settlement and medieval assembly site 9781407312262, 9781407322735

Table of contents :
Front Cover
Title Page
Copyright
Table of Contents
1 Introduction
2 Background
3 Geomagnetic survey
4 Airborne Laser Scanning
5 Excavation Methods
6 Results from the excavation
7 Archaeomagnetic dating
8 The artefacts
9 The animal bones
10 Human bone remains
11 Interpretation and discussion
12 Acknowledgements
13 Bibliography
14 Authors

Citation preview

BAR 592 2014 COOLEN & MEHLER EXCAVATIONS AND SURVEYS AT THE LAW TING HOLM

B A R

Excavations and Surveys at the Law Ting Holm, Tingwall, Shetland An Iron Age settlement and medieval assembly site

Joris Coolen Natascha Mehler

BAR British Series 592 2014

Excavations and Surveys at the Law Ting Holm, Tingwall, Shetland An Iron Age settlement and medieval assembly site

Joris Coolen Natascha Mehler with contributions by Günther K. Kunst, Zoe Outram, Sam E. Harris, Cathy M. Batt, Louise Brown, Erich Nau, Michael Doneus, Anthony Newton and Karin Wiltschke-Schrotta

BAR British Series 592 2014

ISBN 9781407312262 paperback ISBN 9781407322735 e-format DOI https://doi.org/10.30861/9781407312262 A catalogue record for this book is available from the British Library

BAR

PUBLISHING

Table of contents 1

Introduction ......................................................................................................................................1

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Background .......................................................................................................................................3 2.1 Site location, topography and geology ................................................................................................3 2.2 Historical background ..........................................................................................................................4

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Geomagnetic survey .......................................................................................................................7 3.1 Survey area ............................................................................................................................................7 3.2 Methodology .........................................................................................................................................8 3.2.1 Survey grid ........................................................................................................................8 3.2.2 Instrumentation .................................................................................................................8 3.2.3 Data processing .................................................................................................................8 3.3 Results .................................................................................................................................................8 3.3.1 General characteristics ......................................................................................................8 3.3.2 Areas 1–4 ..........................................................................................................................8 3.3.3 Area 5 ................................................................................................................................15 3.3.4 Area 6 ................................................................................................................................16 3.3.5 Area 7 ................................................................................................................................16 3.3.6 Area 8 ................................................................................................................................17 3.4 Discussion .........................................................................................................................................17

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Airborne Laser Scanning by Joris Coolen and Michael Doneus ...........................................................19 4.1 Introduction .......................................................................................................................................19 4.2 Data collection and processing ...........................................................................................................19 4.3 Interpretation ..................................................................:..................................................................22 4.3.1 Law Ting Holm, St. Magnus Church and Griesta ............................................................22 4.3.2 Loch of Tingwall................................................................................................................22 4.3.3 Tingwall Valley ..................................................................................................................25 4.4 Discussion .........................................................................................................................................30 4.5 Acknowledgements ...........................................................................................................................30

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Excavation Methods .....................................................................................................................31 5.1 Location of trenches ..........................................................................................................................31 5.2 Excavation and documentation methodology ...................................................................................33 5.2.1 Excavation survey ..............................................................................................................33 5.2.2 Photographic documentation ............................................................................................33 5.2.3 Recovery of finds and sampling ..........................................................................................34

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Results from the excavation ........................................................................................................35 6.1 Trench 1 ..............................................................................................................................................35 6.2 Trench 2 ..............................................................................................................................................52

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Archaeomagnetic dating by Zoe Outram, Samuel E. Harris and Cathy M. Batt ..........................................57 7.1 Archaeological Context ....................................................................................................................57 7.2 Sampling ...........................................................................................................................................58 7.3 Measurements ...................................................................................................................................58 7.4 NRM Results: AM193 (T1-T14) ........................................................................................................58 7.5 NRM Results: AM202 (T15-43) ........................................................................................................58 i

7.6 Archaeomagnetic dating ...................................................................................................................60 7.7 Summary ...........................................................................................................................................62 7.8 Appendix: The magnetic data ...........................................................................................................63

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The artefacts .....................................................................................................................................65 8.1 The prehistoric pottery by Louise Brown ..............................................................................................65 8.1.1 The assemblage ................................................................................................................65 8.1.2 Reworked sherds .............................................................................................................69 8.1.3 Summary ..........................................................................................................................70 8.2 The post-medieval artefacts by Natascha Mehler ..................................................................................70 8.2.1 Trench 1 ............................................................................................................................70 8.2.2 Trench 2 ............................................................................................................................70 8.3 Pumice by Anthony Newton .................................................................................................................73 8.3.1 Pumice Description .........................................................................................................74 8.3.2 Origin of the Pumice ........................................................................................................74 8.3.3 Summary ..........................................................................................................................74 8.4 Stone artefacts by Joris Coolen ........................................................................................................74 8.4.1 Cobble tools .....................................................................................................................74 8.4.2 Flaked and chipped laminated stones ..............................................................................77 8.4.3 Unclassified stone finds .....................................................................................................79 8.4.4 Discussion .......................................................................................................................80 8.4.5 Catalogue of stone artefacts .............................................................................................80 8.4.6 Acknowledgements ..........................................................................................................85 8.5 Archaeometallurgical analysis by Erich Nau .................................................................................85 8.5.1 Sampling ..........................................................................................................................85 8.5.2 Analysis ...........................................................................................................................85 8.5.3 Observation .....................................................................................................................85 8.5.4 Interpretation ..................................................................................................................91 8.6 Metal artefacts by Joris Coolen and Natascha Mehler ...........................................................................91

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The animal bones by Günther Karl Kunst .............................................................................................93 9.1 General characteristics ...................................................................................................................92 9.2 Species composition .......................................................................................................................92 9.3 Observations on the domestic mammals ........................................................................................94 9.3.1 Age structure ...................................................................................................................94 9.3.2 Occurrence of neonatal/foetal bones ...............................................................................95 9.3.3 Epiphyseal fusion ............................................................................................................96 9.3.4 Tooth eruption and attrition ..............................................................................................97 9.3.5 Sexing ...............................................................................................................................99 9.4 Taphonomic observations ...............................................................................................................99 9.4.1 Skeletal part representation ............................................................................................99 9.4.2 Butchery marks ..............................................................................................................101 9.4.3 Natural modifications ....................................................................................................104 9.4.4 Burnt bones ....................................................................................................................105 9.4.5 Pathologies and abnormalities ......................................................................................105 9.5 Bird remains .................................................................................................................................106 9.6 Fish ...............................................................................................................................................108 9.7 Osteometric results .......................................................................................................................108 ii

9.8 Worked bone .................................................................................................................................110 9.8.1 Bone artefacts ................................................................................................................110 9.8.2 Manufacture debris ........................................................................................................113 9.9 Short comments on the mollusc remains ................................................................................115 9.10 Summary ....................................................................................................................................115

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Human bone remains by Karin Wiltschke-Schrotta .............................................................................117

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Interpretation and discussion ..................................................................................................119 11.1 Trench 1 – Law Ting Holm .........................................................................................................119 11.2 Trench 2 – the causeway ..............................................................................................................122 11.3 The prehistoric settlement at the Law Ting Holm in context .....................................................125 11.4 The Law Ting Holm after the Pictish Period ..............................................................................126

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Acknowledgements .....................................................................................................................129

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Bibliography ...................................................................................................................................131

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Authors ............................................................................................................................................137

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1

Introduction

In May 2011, a team of archaeologists from the Department of Prehistory and Historical Archaeology of the University of Vienna, assisted by colleagues from the Czech Republic and Norway, carried out a research excavation at the Law Ting Holm in Tingwall on Shetland’s Mainland (Fig. 1). The site is believed to be the place of the main assembly of Shetland, which was in use most likely from the Norse period to the second half of the 16th century. The excavation was part of “The Assembly Project (TAP)–Meeting places in Northern Europe AD 400–1500” (hereinafter referred to as TAP), a research project that took place from June 2010 to November 2013 and was funded by HERA, a joint research programme (www.heranet.info) of the European Community FP7 2007–2013, under the Socio-Economic Sciences and Humanities Programme. The excavation followed an extensive geomagnetic survey carried out in June 2010 (Coolen and Mehler 2010). The fieldwork was directed by Natascha Mehler and Joris Coolen.

Fig. 1. Location of the site (geodata: ESRI).

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Background

A number of assembly sites from the Viking period and the Middle Ages are known throughout Northern Europe, but only a few exist at which the actual court of justice can be pinpointed as in Tingwall. It is for this reason that the Law Ting Holm is considered a key site for TAP, an international collaborative project on the role of assemblies (things) in the creation of collective identities and emergent kingdoms in medieval Northern Europe.

2.1 Site location, topography and geology Tingwall is located to the north of the Loch of Tingwall, approximately 4.5 km north–northeast of Scalloway and 6 km northwest of Lerwick, on Shetland’s Mainland. The lake and the eponymous settlement are situated in the centre of a long valley extending from the East Voe near Scalloway in the south to Lax Firth in the north (Fig. 2). The valley thus provides a natural passageway across Mainland, from its eastern North Sea coast to the western Atlantic coast.

Fig. 2. Topography of the Loch of Tingwall. The Law Ting Holm is situated at the north end of the lake (© Crown Copyright/database right 2010. An Ordnance Survey/EDINA supplied service).

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Fig. 3. View of the Law Ting Holm. Georeferenced and colour enhanced aerial photograph taken by Dave Cowley for the RCAHMS on 16 June 2010 (photo ref.no. DP082229 and DP082232. © RCAHMS). Tingwall Valley is one of Shetland’s most fertile areas. This is especially true of the northern and gentler part of the valley, which currently also hosts Tingwall Airport; the southern part is somewhat steeper. The water level of the Loch of Tingwall lies at approximately 8 m O.D. On the west side of the lake, the hills rise up to 112 m, while those on the east side reach an elevation of 146 m. Geologically, the valley of Tingwall consists of a number of parallel formations. On the lower part of the western shore, the bedrock consists of micaceous psammite and semipelite (metamorphosed sandstone and siltstone) of the Wadbister– Ness Formation. The Lax Firth limestone formation runs through the centre of the lake and is flanked by a narrow strip of metalava and metatuff of the Astarte bed in the east. The eastern shore of the lake consists mainly of semipelite of the Clift Hills Phyllitic Formation. In most parts of the valley, the bedrock is covered by till left by the glaciers at the end of the last ice age. The lake is surrounded by a strip of marshland that reaches a maximum width of 120 m to the southwest of Tingwall Manse. The main area of the assembly site is a small promontory on the north side of the lake, known as Law Ting Holm (Fig. 3). The Holm is formed by an outcrop of local limestone of the Lax Firth formation, with

large quartz veins. The top of the Holm today rises approximately 2.5 m above the mean water level. It is connected to the shore by a marshy area, which today is only submerged during periods of heavy rainfall. As the name (Old Norse “Holmr” = a small island) indicates, the Law Ting Holm was an islet in the lake. 2.2 Historical background For many centuries, Tingwall was the main assembly site of Shetland, where the regular meetings of the law thing, the islands’ parliament and upper court, took place. The name itself is derived from Old Norse þing völlr, meaning the “parliament or court field(s).” Similar names can be found elsewhere in Scandinavia and the British Islands—the most famous example being the world heritage site Þingvellir in Iceland—and usually refer to the main assembly site in a legislative area (Fellows-Jensen 1996, 16ff.). The law thing at Tingwall, the representative assembly at which royal laws were introduced and enforced, is recorded in several written documents, the oldest of which dates from 1307 (SD I, no. 3), but it may well go back earlier (Fellows-Jensen 1996, 22; Smith 2009, 38). The site fell out of use when Lord Robert Stewart moved the assembly from Tingwall to Scalloway in the 1570s (Smith 2009, 39; Sanmark 2013, 98). 4

Fig. 4. View of the causeway leading towards the church.

Fig. 5. The Loch of Tingwall as seen from the manse. Watercolour by Thomas Woore, 1828. The Law Ting Holm is shown in the foreground, Scalloway castle at the centre. 5

According to local tradition, the assembly met annually at the Law Ting Holm. The location is confirmed by a report from 1577 referring to an older document issued by the law thing “in the ting Holm of Tingwale” in 1532 (SD I, no. 237, p. 196). The assembly site was connected to the former St. Magnus Church (now Tingwall Kirk) which was probably built in the late 12th century. It was the main parish church in Shetland and the seat of the archdeacon before the Reformation (Cant 1975, 21). In fact, the first surviving document that mentions the assembly at Tingwall records that the meeting was held “in the church at Þingavollr” (SD I, no. 3). A causeway, assumed to be used at the time, leads directly from the Law Ting Holm to the church. Currently, the Ting Holm constitutes a promontory on the northern lake side. Previously, the Holm was an island, located 40–50 m from the shore and surrounded by shallow water. In the mid 19th century, the lake was artificially lowered (Coolen and Mehler 2010, fig. 3 and 23). Apart from the causeway (Fig. 4), there are no visible remains of the alleged assembly site. However, in 1701, John Brand reported that “three or four great Stones are to be seen, upon which the Judge, Clerk and other Officers of the Court did sit” (Brand 1701, 121). A similar account was recorded by James Robertson, a visitor in Shetland in 1769. He reported that “The Isle … is composed of stones thrown together carelessly, but there are four larger than the rest, on which, according to tradition Judges sat. The people waited without the Lake” (Douglas and Dickson 1994, 145).1 A very similar description from the same year states that “Large stones placed at such a distance that a person could step from one another formed the Entry to the Court.” (Henderson and Dickson 1995, 145). According to George Low, writing in 1774, the stones on the Holm were later torn up to clear the area for grazing (Low 1879, 77). John Brand also gives an account of how the meetings were carried out at Tingwall: “All the Country concerned to be there, stood at some distance from the Holm on the side of the Loch, and when any of their Causes was to be Judged or Determined, or the judge found it necessary that any Person should compear before him, he was called upon by the Officer, and went in by these stepping stones, who when heard, returned the same way he came.” (Brand 1702, 121–122). The stepping stones mentioned by Brand are clearly visible on a water colour by Thomas Woore from 1828 (Fig. 5) and also on a water colour by Sir Henry Dryden, dating to ca. 1855 (Fig. 6). Brand also tells of the damage done to the grass land by

Fig. 6. The Law Ting Holm on a watercolour by Sir Henry Dryden, ca. 1855. the many horses of the people attending the assembly: “At every end of the Loch there is a House, upon whose Grass the Country Men coming to the Court did leave their Horses, and by reason the Masters of the Houses did suffer a loss this way, they were declared to be Scat free…” (Brand 1701, 122). Two more descriptions are handed down from the 19th century. Samuel Hibbert writes in 1822 that “The court where the Chief Magistrate of Shetland issued out his decrees, was in a small Holm at the head of the adjoining loch, from which there was a communication to the shore by means of large stepping-stones.” (Hibbert 1822, 99). About 60 years later, John Tudor writes that the assembly was held “on what, till quite recent years, was a Holm in the Loch of Tingwall, just under the Manse, but which, since the level of the loch has been lowered by drainage, has now become a portion of the shore.” (Tudor 1883, 20). In 1946, the Ting Holm was recorded by the RCAHMS, and it was stated that “at the outer end of the causeway, where it reaches the Holm, a wall, apparently of no great thickness or strength seems to have run off at right angles on each side, to enclose the whole island. Traces of another wall of irregular outline appear at the landward end of the causeway” (RCAHMS 1946: 124, No. 1522).2 However, both statements were revisited after a new survey in 1968 because “no trace of walling at the Holm end of the causeway” could be identified, while “the irregular wall at the landward end” was interpreted as an old field wall, most likely not related to the assembly site. Nevertheless, the site was described as a “thingstead” by Historic Scotland in 1996 (Index No. 2074).

We would like to thank Brian Smith of the Shetland Archives for this information.

RCAHMS Site no. HU 44SW 11. See http://canmore.rcahms.gov.uk/ en/site/1104/details/law+ting+Holm/ (last accessed July 21, 2013).

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Fig. 7. Overview of the geomagnetic survey data collected in 2010. Greyscale plot of the processed survey data, clipped to 0.5 standard deviation (background map © Crown Copyright/database right 2010. An Ordnance Survey/EDINA supplied service).

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Geomagnetic survey

In 2010, a geomagnetic survey was carried out over the Law Ting Holm and the surrounding area along the northern shore of Loch of Tingwall. The aim of this survey was to detect archaeological structures that might be related to the Norse or medieval assembly site. Although there may have been no permanent structures at the site, assembly sites in northern Europe are sometimes marked by the remains of temporary housing or cooking activities (e.g., Vésteinsson 2013). Older structures, such as burial mounds, were sometimes incorporated in the assembly site and may have given it a certain historical justification (e.g., Sanmark and Semple 2010). Considering the wide range of features that might thus be expected at such sites and given the humidity of the marshland surrounding the Law Ting Holm, magnetometry seemed the most appropriate geophysical prospection method.

3.1 Survey area A total area of 9.3 hectares was surveyed on eight days between 1 and 21 June 2010. Because of the many obstacles (fences, ditches, roads, lake) present, the survey area had to be subdivided. For reference, separate survey areas were identified and numbered 1 to 8 (Fig. 7). Areas 1, 2 and 3 comprise the whole surveyed area west of the road, which had to be divided into three parts due to metal fences. Area 4 is the narrow strip on the western side of the lake, enclosed by the road and the lake. The Law Ting Holm and the marshland to the north constitute area 5. Area 6 is located north of area 5 and is separated from it by a fence. Area 7 comprises two grid squares in the field south of Tingwall Manse. Area 8, the largest contiguous area, covers the pasture to the east and southeast of Tingwall Manse.

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3.2 Methodology 3.2.1 Survey grid The survey was carried out over a grid of 40-m squares. The survey grid was laid out using a geographical information system (GIS) and staked out with a total station by a commercial surveyor. To make the best use of space, a separate grid was laid out for each of the survey areas. Nevertheless, individual grid squares or traverses sometimes had to be shortened to avoid obstacles. 3.2.2 Instrumentation The survey was carried out with a multisensor fluxgate gradiometer system produced by Sensys (Fig. 8). Where ground conditions permitted the use of a cart, we used five FGM-650B gradiometers. The marshy parts of the survey area along the lake side were surveyed with a handheld system, using three FGM-650 probes. In both cases, the probes were spaced at 0.5-m intervals. Samples were taken at 0.1-m intervals and stored using a Sensys DLM-98 data logger. The Sensys gradiometer system uses a logarithmic measuring mode: measurements are taken continuously and re-sampled to the set number of samples (grid length/sample interval) at the end of each traverse. The Sensys FGM650 gradiometers have a resolution of 0.1 nT at a total range of +/- 3000 nT. The two single-axis fluxgate sensors in every probe are spaced 650 mm apart.

Fig. 8. The multichannel fluxgate gradiometer system in use at Tingwall.

properties of the local bedrock, which produce very large and very strong anomalies. Such anomalies were mainly encountered on the slopes towards the edges of the surveyed area, where the rock crops out. Most of these anomalies show a clear NNE–SSW or N–S orientation, which is consistent with the general orientation of the geological formations in the valley. The geological anomalies can be classified into two different types, namely, the narrow, repeating bands visible in the western part of the survey area and the much stronger, irregularly shaped, bipolar anomalies in areas 6, 7 and 8. The two types most likely correspond to different geological formations. The large anomalies caused by bedrock geology are limited to certain parts of the survey area and do not altogether impede the use of geomagnetic prospection in Tingwall. The extremely high magnetic response of the local bedrock does, however, imply that single stones of the same material can also cause strong anomalies. This is exemplified by the stones of the causeway and the stone alignment leading away from it: both can be clearly identified as a series of small anomalies, with maximum values ranging from 6.2 to 126.1 nT (see Chapter 3.3.3). Indeed, many small, mainly positive anomalies were encountered throughout the survey area, most of which are doubtlessly caused by buried stones. However, the value range overlaps with the values caused by ferromagnetic or thermoremanently magnetised features. Many anomalies are therefore difficult to interpret. Moreover, the strong magnetisation of the bedrock and soil formations in Tingwall hampers the identification of archaeological features, which usually cause much weaker signals.

3.2.3 Data processing At the end of each day, the data were downloaded to a notebook using the software Sensys MAGNETO®ARCH and subsequently exported for further processing in ArcheoSurveyor 2.5.4.0. Processing included de-striping, de-staggering and interpolating. Striping in the data was reduced by subtracting the median from each traverse, except for traverses with very large and strong anomalies. In these cases, the application of a median filter would have caused a strong mismatch between adjacent grids or traverses. A low-pass filter with a small window of 3 × 3 measurements and Gaussian weighting was used instead for these areas. Obvious shifts between adjacent traverses, caused by irregular walking speeds, were corrected by manually shifting (parts of) the traverses. Finally, the data were interpolated across the traverses to a more regular grid size of 0.125 × 0.1 m and subsequently exported to and georeferenced in ESRI ArcMap. 3.3 Results 3.3.1 General characteristics With a standard deviation of 55.0 nT and extremes of 2,391.8 and -2,496.0, the magnetic response encountered at the site is extremely strong (see Fig. 7). This strong magnetic response is mainly due to the magnetic

3.3.2 Areas 1–4 The survey of areas 1 to 4 did not reveal any obvious archaeological features, although the problems

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mentioned above apply to many of the smaller non-linear anomalies. Some of these, most notably two stronger positive anomalies in area 1, 1 to 1.5 m in diameter, could possibly represent anthropogenic pits with positively magnetised fillings. The larger anomalies encountered in areas 1–4 all represent natural or modern features. As mentioned before, the upper part of areas 1 and 2 is marked by a series of strong parallel anomalies caused by magnetic minerals in the metamorphic bedrock (Fig. 9, 10a). The parallel, stripy anomalies are cut through at a right angle by another, much stronger (max. 1319.7 nT) and wider bipolar anomaly in the northern part of area 2 (Fig. 9, 10b). The shape and intensity of the anomaly suggest that it may have been caused by a lightning strike (cf. Maki 2005; Faßbinder 2009, fig. 7–8). A similar anomaly can be observed in the northern half of area 4 (Fig. 9, 10h). Although this anomaly is smaller and much weaker than the large anomaly in area 2, it may also be the result of a lightning strike. At the bottom of the slope in areas 1 and 2, there are two large positive anomalies (Fig. 9, 10c) that may have been caused by enhanced soil magnetism, possibly due to waterlogging or deposition of magnetic minerals from upslope. A backfilled gully network appears in the south of area 1 (Fig. 9, 10d). A number of weakly positive linear anomalies that form a large herringbone pattern running through areas 1 and 2 are caused by modern drains (Fig. 9, 10e). In the southern half of area 1, two shorter lines run across the drainage system (Fig. 9, 10f). The former may also be interpreted as backfilled ditches or trenches, but they are most likely not part of the same drainage system. In area 2, the central trench of the drainage system is crossed by a wavy line, which also appears as a weak positive anomaly (Fig. 9, 10g). The irregular course does not imply any intentional design; the anomaly may represent a (refilled) cattle track.

of the interpretation of the other positive anomalies on and around the Holm but also underlines the problem mentioned before of similar responses for rocks and archaeological features. The magnetic anomalies along the edge of the Holm may be caused by the protruding bedrock, as demonstrated by the high positive and negative values encountered over the bare rocks along the southeastern shore of the Holm, but they could also represent anthropogenic deposits. The northern part of the Holm appears “noisy” compared to the southwestern (and highest) corner. The excavation of trench 1 has shown that this “noise” is caused by mixed rubble and midden layers containing burnt materials and various types of stones. The geomagnetic data suggest that these layers do not cover the southwestern part of the Holm. During the survey, a depression was noted at the centre of the Ting Holm, framed by a large and heavily cracked quartz outcrop.3 It was suggested that the rock may be fire cracked and may mark the edge of a fire place. The geomagnetic data do not seem to support this theory. The edge of the depression appears in the geomagnetic data as a negative anomaly (Fig. 11, 12c). This is mainly the result of different sensor heights. Although heating of the rock itself would not necessarily have led to increased magnetisation, the adjacent area does not bear signs of thermoremanent magnetisation. In the original RCAHMS record for the Law Ting Holm, it was noted that “at the outer end of the causeway, where it reaches the Holm, a wall, apparently of no great thickness or strength seems to have run off at right angles on each side, to enclose the whole island” (RCAHMS 1946, 124). During later site visits, this wall could not be observed, nor does it appear on historical images of the Holm. There is no evidence of a wall surrounding the Holm in the geomagnetic data, but the rectangular shape of the Holm is indeed remarkable. Although the anomalies along the edge may be caused by natural features, the shape may have been humanly modified. This interpretation is also supported by the fact that the three sides of the Holm that are most visible from the lakeside, in the north, west and east, stand out most clearly. This is in contrast to the present elevation; the Holm slopes down towards the north and ends rather abruptly at the southern end. The rectangular shape of the Law Ting Holm is also noticeable in aerial photographs (see Fig. 3). The sharp outline is emphasised by vegetation marks: marsh marigolds (Caltha palustris), which abound in the marshland at the lake side, are absent at the Holm, while patches of yellow flags (Iris pseudacorus) mark the border between the marshland and the higher land (i.e., the old shoreline) at both ends of the causeway. The causeway appears as a series of small, positive anomalies caused by the stones (Fig. 11, 12b).

3.3.3 Area 5 The Law Ting Holm, at the southern end of area 5, produces a series of strong anomalies and clearly stands out from the “quiet” surrounding marshland (Fig. 11, 12a). The Holm itself appears as a rectangle of 25 × 21 m with rounded corners. The outline is marked by a linear, negative anomaly in the west, north and east (Fig. 11, 12a), framed on the inside by a series of positive anomalies (Fig. 11, 12b). In 2010, we assumed that the positive anomalies detected on the Law Ting Holm were all caused by rocks, although it was stated that “the detected stones at Law Ting Holm could be natural or part of archaeological features” (Coolen and Mehler 2010, 26). The excavation has shown that the positive anomalies within trench 1 were indeed caused by archaeological features, but of a different sort, namely, concentrations of peat ash and burnt matter (see Chapter 6.1). This urges a reconsideration

3 The quartz outcrop marked the southeastern corner of trench 1 and is clearly visible in the excavation photos.

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Fig. 9. Geomagnetic survey data of areas 1 to 4. Greyscale plot of the processed survey data, clipped to 0.5 standard deviation of the entire dataset (background map © Crown Copyright/database right 2010. An Ordnance Survey/EDINA supplied service).

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Fig. 10. Interpretation of the geomagnetic survey data from areas 1 to 4 (background map © Crown Copyright/database right 2010. An Ordnance Survey/EDINA supplied service).

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Fig. 11. Geomagnetic survey data of areas 5 to 7. Greyscale plot of the processed survey data, clipped to 0.5 standard deviation of the entire dataset (background map © Crown Copyright/database right 2010. An Ordnance Survey/EDINA supplied service).

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Fig. 12. Interpretation of the geomagnetic survey data from areas 5 to 7 (background map © Crown Copyright/database right 2010. An Ordnance Survey/EDINA supplied service).

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Fig. 13. Geomagnetic survey data of areas 7 and 8. Greyscale plot of the processed survey data, clipped to 0.5 standard deviation of the entire dataset (background map © Crown Copyright/database right 2010. An Ordnance Survey/EDINA supplied service). However, not all stones produce magnetic anomalies. Remarkably, there are no significant anomalies where both flanks of the causeway stand out most clearly in the field, towards its southern end. In contrast, the geomagnetic survey reveals several stones at the northern end that are hidden beneath the surface. The causeway stops at the old shoreline and does not seem to continue into the present field. The last stones that can

still be associated with the causeway are not aligned, indicating that the upper end of the causeway may have been disturbed in later ages. Both the geomagnetic data and the aerial photographs show that the causeway is not aligned with the centre of the Holm but rather is shifted to the west. The geomagnetic data also show the loose stone alignment that follows the old shoreline from the upper part

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Fig. 14. Interpretation of the geomagnetic survey data from areas 7 and 8 (background map © Crown Copyright/database right 2010. An Ordnance Survey/EDINA supplied service).

not as well aligned as those of the causeway and are very loosely spaced. The stone alignment connects to an existing field wall in the northwest, which shows a remarkable curve near the junction (see Fig. 3). The curved wall does not, however, appear in the geomagnetic data. Along the causeway and the stone alignment mentioned above, there are a number of dipole anomalies that

of the causeway to the northwest (Fig. 11, 12f). These are most likely identical with the traces of another wall of irregular outline at the landward end of the causeway recorded by the RCAHMS (1946, 124).4 The stones are http://canmore.rcahms.gov.uk/en/site/1104/details/law+ting+Holm/ (last access 18-11-2013). Canmore ID 1104, Site no. HU44SW 11. During the revised survey in 1968, it was stated that the irregular wall at the landward end is an old field wall.

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could be caused by either igneous stones or ferrous objects (Fig. 11, 12d). One of these anomalies was included in trench 2. No iron objects were found during the excavation of trench 2 that could explain the anomaly. This indicates that the anomaly was caused by the large causeway stone at the western flank, although it is possible that an iron object was removed unnoticed with the grass sods. Some 50 m to the north of the stone alignment mentioned above, another, parallel alignment of strong bipolar anomalies was observed (Fig. 11, 12g). These anomalies can likewise be interpreted as ferrous objects or igneous rocks. Given the parallel orientation to the previously discussed stone alignment, these features may mark a contemporary field enclosure, possibly a sub-recent fence. To the north and northwest of the causeway, several linear yet rather vague anomalies can be observed running parallel to the former (Fig. 11, 12e). These anomalies may represent natural rather than archaeological features. It must be stressed that the direction of the causeway parallels the general orientation of the valley, which is in turn determined by the geological structure.

These anomalies are most likely caused by the weakly magnetised filling of ditches or trenches. The function of these ditches cannot be concluded from the magnetic data. However, they might be relatively recent because the two parallel stretches run in the same direction as the fence ahead of them and at a right angle to the ploughing direction. More interesting from an archaeological point of view is a rather vague linear anomaly in the eastern half of the area that is aligned with the causeway (Fig. 11, 12o). This anomaly could indicate a (gravel) track leading up to the church in continuation of the causeway. The northeastern corner of area 6 is marked by an alignment of sixteen strong, positive anomalies 0.5 to 1 m in diameter and spaced 2 m apart (Fig. 11, 12p). A larger anomaly at the eastern end (Fig. 11, 12r) may also be part of this group, but is not exactly aligned and could therefore also be natural. The anomaly strengths of these features range from 12.2 to 199.3 nT but mostly lie between 30 and 80 nT. These values seem rather high for regular pit fillings and correspond to thermoremanently magnetised or ferromagnetic objects. However, the anomalies lack the dipoles typical of the latter. The alignment runs WNW–ESE towards Tingwall Manse and may be associated with the latter, but it could also predate the present infrastructure. In fact, the alignment is oriented perpendicular to the causeway and its tentative extension discussed above. Most of the smaller anomalies encountered in area 6 may be caused by buried stones and ferrous objects. However, on the basis of their shape, size and anomaly strength, some of them may possibly represent archaeological features such as pits. Except for the alignment of pit-like anomalies in the northeastern corner, there are no obvious clusters of possible archaeological features, and it is hard to put these smaller anomalies into context.

3.3.4 Area 6 Area 6 is dominated by a number of very strong, irregularly shaped, bipolar anomalies, most likely caused by igneous bedrock (Fig. 11, 12h). They run diagonally through the northeastern corner of the area, with values ranging from 2,347.0 to -1,437.4 nT, and continue into areas 7 and 8. According to the geological survey, the local bedrock in these areas comprises metamorphosed igneous and sedimentary rocks (metalava, metatuff, metalimestone and semipelite). The striping in the eastern half of area 6 is caused by recent tillage marks, some of which constitute larger, linear anomalies (Fig. 11, 12i). The sharp contrast between the western and eastern parts of the survey area can be attributed mainly to the varying effect of the applied de-striping function. A negative linear anomaly runs in a slight curve through area 6 in the WNW–E direction and continues into area 7 (Fig. 11, 12j). There, it runs towards a concrete reservoir (Fig. 11, 12k). The line is therefore interpreted as a modern water conduit. Possibly associated with this water conduit are two weak positive anomalies that run through the central and northeastern part of area 6 (Fig. 11, 12m). The two parallel lines converge with or cross the water facility mentioned before. The two lines run more or less in the W–E direction, approximately 3.5 m apart, before taking a sharp turn towards Tingwall Manse. After this turn, the two lines converge; only the southern anomaly continues in a straight line for at least 60 m. This line possibly extends further south as well, where a short and less clear linear anomaly aligns with it (Fig. 11, 12n).

3.3.5 Area 7 The small area between Tingwall Manse and the lake is dominated by large geological anomalies that are most likely caused by igneous bedrock (Fig. 11, 12s). Rocky outcrops also prevented surveying in the northwestern part of the area. The anomalies have a more regular outline than their counterparts in area 6 and consist of alternating positively and negatively magnetised N–S-oriented stripes. The strong magnetisation of the bedrock geology masks potential smaller and more subtle anomalies, apart from a concrete reservoir with a metal lid located near the centre of the area (Fig. 11, 12k). The negative linear anomaly that crosses area 6 and continues into area 7 runs towards this reservoir but then bends to the northeast (Fig. 11, 12j). Only in the western quarter can a number of smaller (but still fairly large) anomalies be made out. These anomalies may also be caused by rocky outcrops just below the surface, but could also represent

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discrete anomalies that appear to be similar to those caused by archaeological features. These may have high values, similar to those produced by ferrous or thermoremanently magnetised features, but much lower values are possible too, depending on the size, depth and orientation of the object. Hence, the anomaly strength hardly presents a clue to the interpretation. The vast majority of small anomalies can therefore not be readily interpreted. Based on their shape, distribution and (less so) magnetisation, some anomalies were interpreted as possible archaeological features, but we deliberately refrain from a further classification. Archaeologically speaking, the most interesting results were obtained at the Law Ting Holm. Although we were careful in our initial interpretation of the anomalies encountered at the Holm, the excavation showed that these anomalies are partly caused by peat ash deposits and other fired material. The geomagnetic data can therefore be used to predict the extent of the cultural layers at the Law Ting Holm. Furthermore, it was noted that the Holm appears to be very regular in shape in the geomagnetic data, especially on the sides that directly face the shore. This could imply that the outline of the Holm was artificially modified to highlight its significance or to adhere to legal presetting of the court site. The survey also showed that the causeway continues for at least 20 m further north than is currently visible in the field. A possible connecting track was identified between the causeway and the church. If we assume that a crowd gathered at the northern end of the Loch of Tingwall every year for several centuries, presumably for several days in a row each time, it is likely that they left traces behind. Indeed, some of the smaller anomalies that occur throughout the surveyed area might be rubbish pits, substructures for shelters, fireplaces or (metallic) objects lost by the attendants of the assembly. Most of the anomalies that were interpreted as possible archaeological features are located in areas 6 and 8. Some clustering can be observed, but clear structures are not apparent. Neither a series of augering tests nor an initially planned small excavation trench to disclose the nature of some of the smaller anomalies in area 8 could be completed. Thus, the geomagnetic survey provides a starting point rather than a final answer to the question of whether the slopes surrounding the Law Ting Holm hide the remains of many assembly gatherings.

archaeological features (Fig. 11, 12t). The remains of a large field wall are still visible at the western edge of area 7 and cause similar positive and negative anomalies (Fig. 11, 12v). 3.3.6 Area 8 Large and strong anomalies caused by bedrock geology, similar to those encountered in areas 6 and 7, are located along the western and eastern edges of area 8 (Fig. 13, 14a). A number of larger, irregularly shaped positive and negative anomalies, clustered in the northern half of the area, may also be caused by geological or soil features (Fig. 13, 14b). What is most striking about area 8 is the large number of small positive anomalies of varying strength that occur throughout the area. Similar anomalies were also encountered in the other areas, but not at the same density. Again, most of these anomalies may be caused by single stones, although some exhibit the high values and bipolarity typical of ferrous objects. However, some of these anomalies seem rather large for a single stone and have a regular, near-round shape. These anomalies may be tentatively interpreted as possible archaeological features (Fig. 13, 14c). Some of these features constitute small clusters of up to eight pit-like anomalies. Six roughly aligned pit-like structures are visible in the southwest part of the area. Three negative linear anomalies appear at the western edge of area 8 (Fig. 13, 14d). One straight line runs NW–SE towards the gate in the northwestern corner of the field and may hence represent a modern track. This anomaly crosses two similar anomalies, one of which is slightly curved and runs N–S towards the start of a modern drain, while the other is straight and runs NE–SW. The former may also represent a modern animal track, while the latter is aligned with the negative linear anomaly in area 7 and may thus be part of a water conduit system. 3.4 Discussion Although the magnetic response encountered at the site was predominantly good, the interpretation of the data is severely hampered by the strong magnetisation of the local bedrock. The strong anomalies caused by near-surface bedrock outcrops mask potential archaeological features in some parts of the surveyed area. More problematic, however, is the fact that single stones in the subsoil can be expected to produce

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4

Airborne Laser Scanning By Joris Coolen and Michael Doneus

4.1 Introduction Airborne Laser Scanning (ALS), also called airborne lidar (light detection and ranging), is a relatively new remote sensing technique that uses a laser to scan the earth’s surface and create high-resolution elevation models. ALS quickly produces high quality terrain models of large areas and can even reveal a subtle relief that is barely visible to the naked eye. Special filters can be applied to filter out the reflection of trees and shrubs, ‘virtually’ stripping the landscape bare. ALS can therefore also be used in forested areas. ALS has become very popular in archaeology over the past decade (Crutchley 2010; Opitz and Cowley 2013) and has been used effectively in various environments to detect historical buildings, roads, field systems, burials, mining sites, military structures, and drainage patterns. Any past activity and process that has left even very faint traces on the present surface can, in theory, be mapped with lidar. Shetland boasts a rich and highly visible archaeological heritage and is therefore a promising landscape for ALS surveys. The archaeological research carried out by The Assembly Project in Tingwall included a lidar survey of the area surrounding the Loch of Tingwall. The main aim of this survey was to search for hitherto unknown structures associated with the Viking Age/ medieval assembly site at the Law Ting Holm. The more general goal was to map all archaeological surface remains in the area to better understand the historical development and cultural landscape of the area. To our knowledge, this is the first archaeological application of ALS in Shetland. The survey can therefore also be considered to be a case study showing the potential of this method in the Northern Isles. ALS-Project Purpose of Scan Time of Data Acquisition Mean Point-Density (last echoes per m2) Strip Overlap Scanner Type Scan Angle (whole FOV) Flying Height above Ground Speed of Aircraft (TAS) Pulse Rate Strip Adjustment Filtering DTM-Resolution

4.2 Data collection and processing Funding for the lidar survey was provided by a grant from the Natural Environment Research Council (NERC), and the study itself was carried out by the Airborne Research and Survey Facility (ARSF) on 18 June 2011 (Table 1). A total area of 5.4 km² was surveyed in 14 parallel and one crossing flight line at altitudes between 485 and 545 m (Fig. 15). High-resolution aerial photographs of the scanned area were taken simultaneously. The scanner logged up to four return echoes for each laser pulse. After georeferencing, the data was delivered strip-wise as ASCII and LAS 1.0 point cloud with a basic classification following the ASPRS standard lidar point classes. The quality of the delivered data was analysed before interpretation using the OPALS software package (Mandlburger et al. 2009). A point density map calculated from the stripwise LAS-files clearly showed that all important areas were covered in sufficient detail for the subsequent analysis. The mean point density is 18 points per m², excluding water surfaces. A stripadjustment was additionally calculated (Kager 2004) to improve the relative accuracy between individual strips and to minimise noise within the overlapping areas. Since the area under investigation is void of trees and other higher vegetation and as we were primarily interested in the ground surface, a digital elevation model (DEM) was calculated from the last echoes of the laser data. ALS data can be visualised in many ways (Kokalj et al. 2013; Challis et al. 2011; Bennett et al. 2012) (Fig. 16). Visualisations are based mainly on a rasterised DEM that is calculated from the point cloud (Fig. 16A). The DEM shows absolute heights and therefore conveys general surface relief but subtle height differences are barely visible. The latter can literally be ‘highlighted’ Tingwall Archaeology 18 June 2011 18 50 % Leica ALS50-II LIDAR 24° 500 m 70 m/sec 150 KHz Yes Robust interpolation (SCOP++) 0.5 m

Table 1. Lidar scan parameters. 19

Fig. 15. Overview of the lidar scan, shaded relief model (lidar data collected by the NERC ARSF in 2011. Background map © Crown Copyright/database rights 2010. An Ordnance Survey/EDINA supplied service).

by a hillshade model, which is calculated on the basis of the DEM and a user-defined solar azimuth and elevation angle (Fig. 16B). Although shading of the DEM results in a comprehensible representation, there is a danger that features will be missed because they align with the light source and do not cast shadows. This problem can be overcome by creating different hillshades with different directions and heights of the illumination source or by combining a hillshade and a slope map (Doneus and Briese 2011).

More sophisticated algorithms that are used to visualise local topographical variance in lidar data are the local relief model (Hesse 2010) (Fig. 16D), the sky-view factor (Kokalj et al. 2011), or positive and negative openness (Doneus 2013) (Fig. 16E, F). The local relief model (LRM) stresses small-scale elevation anomalies by removing the general topography from the original DEM (Hesse 2010) and performs extremely well in very shallow relief. Openness visualizes the “degree of dominance or enclosure of a location” (Yokohama et al. 2002, 257)

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Fig. 16. Different visualisations of lidar data exemplified by the ruins of the North Garth croft. Shading from black (low) to white (high): A – digital elevation model; B – shaded relief model (hill shade); C – slope map; D – local relief model; E – positive openness; F – negative openness. Note the different visibility of the storage pits and outhouses in the yard and the rigs to the north and south of the main building (lidar data collected by the NERC ARSF in 2011). 21

and in this way is similar to the sky view factor. As with LRM, openness is not subject to directional bias, and the relief features highlighted by openness do not contain any horizontal displacement. Additionally, openness offers a clear distinction between relief features and the surrounding topography, and it highlights both the highest and lowest parts of features (Doneus 2013).

A smaller artificial mound lies outside of the western churchyard wall (Fig. 18B). This is most likely a relatively recent dump that may be associated with the westward churchyard extension. The land at the northern lakeside of the Loch of Tingwall has been intensively improved and drained. No structures that can be associated with the Norse/medieval assembly site could be identified along the lakeside. A rectangular feature measuring 10 × 6 m can be observed to the south of the junction at which the road to Griesta leaves the main road (B9074) that crosses Tingwall Valley (Fig. 18C). There is no structure marked on any of the OS maps at this location. The sharp outline of the feature in the lidar scan and its alignment with the existing modern fence indicate a recent origin. The Griesta farm, which lies 800 m to the northwest of the Law Ting Holm, is believed to be one of the oldest farms in Tingwall Valley (Macgregor 1987, 361–364). Its association with the assembly is reflected by both its name and the traditional belief that it was exempt from scat in return for hosting the horses of the assembly attendants (see Chapter 2.2). A Viking Age weaving comb and a rotary quern were found during the construction of a silage pit in 1971 (Coolen and Mehler 2010, 11f.). The approximate location of this discovery is marked on an old edition of the OS map that is kept at the Shetland Archive. It more or less coincides with an artificial mound, 16 m in diameter, that can be observed in the lidar scan and which has a cellar dug into it (HU 4145 4425). This mound may be the supposed midden from which the finds were recovered, but it could also consist of spoil material from more recent building activities. The area around the farm has been substantially modified by building, farming and road construction. It is impossible to tell from the lidar scan if any remains of the medieval farmstead have survived.

4.3 Interpretation The archaeological interpretation of the lidar-derived DEM and its visualisations was performed using a Geographical Information System (GIS). Potentially relevant structures were marked as polygons or lines and were assigned various attributes (interpretation, supposed age, previous discovery, comments). Over 2,500 features were digitised in this way, of which the majority are drainage ditches and furrows. It is often difficult to date these features, and many of them may actually be recent. Various specialists as well as map sources and the aerial photographs taken during the lidar survey were consulted for the interpretation. Many features were examined in the field during a special field trip in August 2013. 4.3.1 Law Ting Holm, St. Magnus Church and Griesta The lidar scan provided a detailed image of the topography of the Law Ting Holm (Fig. 17a). There are no apparent structures. The scan was taken approximately one month after the excavation. The northern end of the backfilled trench 1 is vaguely apparent (Fig. 17b). The causeway can be traced over almost the entire length between the holm and the former lakeshore (Fig. 17c). The lidar scan thus confirms the conclusion, which had been drawn previously from the geomagnetic survey (see Chapter 3), that the buried northern half of the causeway is better preserved than it appears in the field. There is no visible extension of the causeway or any other aligned feature between the old lakeshore and the church. The diagonal groove that crosses the field to the north of the promontory represents the path that was trodden by the excavation team (Fig. 17d). The oldest part of the churchyard of Tingwall is marked by a mound that most likely covers the remains of the medieval St. Magnus church (Fig. 18A).5 It is commonly believed that the turf-covered burial vault that stands at the eastern side of the mound is the only surviving part of the medieval church. However, the scheduling document by Historic Scotland dates the vault to the 17th century.6 The local relief model of the lidar data shows that the mound in the churchyard has a rather regular, oblong shape with a clear east–west orientation. It measures approximately 38 m in length from east to west and 20 m from north to south. A slight ridge that indicates buried walls can be observed along the edge of the mound. 5 6

4.3.2 Loch of Tingwall As previously mentioned, the present water level in the Loch of Tingwall is lower than it was in the past. The water level was apparently lowered artificially by drainage in the second half of the 19th century (see Chapter 2.2). As a result, the Law Ting Holm is now connected to the shore by a tapering promontory. The causeway, which provided access to the holm when it was still an island, now runs across marshy land. The landward end of the causeway therefore indicates the extent to which the lakeshore has shifted. The old shoreline is marked by a low terrace that can be observed in the lidar scan. The digital elevation model that is derived from the lidar data can be used to reconstruct the former extent of the lake (Fig. 19). However, the model represents the modern surface and thus can be used only to approximate the reconstruction of the past landscape. The lowering of the lake level is likely to have triggered

http://canmore.rcahms.gov.uk/en/site/1114/ (accessed 28-11-2013). http://canmore.rcahms.gov.uk/en/site/1115/ (accessed 28-11-2013).

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Fig. 17. Lidar scan of Law Ting Holm with identified features. Local relief model, shading from red (positive) to blue (negative), overlaid on shaded relief (lidar data collected by the NERC ARSF in 2011).

Fig. 18. Lidar scan of Tingwall Kirk and Manse. Local relief model, shading from red (positive) to blue (negative), overlaid on shaded relief. OS MasterMap data shown as black lines (lidar data collected by the NERC ARSF in 2011. MasterMap © Crown Copyright/database rights 2010. An Ordnance Survey/EDINA supplied service). 23

a dynamic chain of soil formation and vegetation processes that are hard to model. Nevertheless, we believe that the vertical changes of the surface around the holm that were initiated by these processes may not amount to more than a few centimetres and do not have a major effect on the reconstruction. At the time of the lidar scan, the water level around the Law Ting Holm was at approximately 9.08 m ODN.7

If the water level is raised by 10 cm, the promontory shrinks but still connects the holm with the land. A rise of 15 cm would cause the promontory to be submerged but the causeway still rises out of the water. The holm becomes a subrectangular island of 27 × 37 m. Sections of the causeway still rise out above the lake even at a lake level rise of 20 cm. The shore slightly shifts to the north with a 20 cm-rise, but the outline of the holm

7 The lidar data show an offset of up to 2 m compared to Ordnance Survey spot heights and the benchmarks measured during the excavation. The elevation model is also slightly tilted because the water level appears to be 22 cm higher at the southern end than at the northern end. This is probably due to an only approximative absolute georeferencing without the usage of absolute control information

(pers. comm. Christian Briese, 26-11-2013). The values given above were recalculated to match the benchmarks but should still be considered to be relative rather than absolute and do not consider the tilt. The data were re-processed by the ARSF after the manuscript of this publication had been finished but due to time constraints, the corrected data could not be included in the analysis.

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Fig. 20. Burnt mounds at Griesta. Shaded relief overlaid on positive openness (lidar data collected by the NERC ARSF in 2011).

Fig. 21. Burnt mounds along Burra Burn. Shaded relief overlaid on positive openness (lidar data collected by the NERC ARSF in 2011).

remains almost the same as with a 15 cm-rise. With a 25 cm-rise, only the terminal parts of the causeway would protrude from the water. This indicates that the drainage of the lake in the 19th century has reduced the water level by 15 to 20 cm.

The second pair is located at the northern foot of Burra Dale (Fig. 21, 22A–B). Both mounds are crescent-shaped. The northernmost mound has a diameter of 14 m and points westward (HU 4240 4329). The second mound is located 30 m to the south (HU 4239 4324). It has a diameter of 12 m and points northeastward. Neil Anderson reported the mounds before the year 2000 to the Shetland Amenity Trust as tentative house sites (Coolen and Mehler 2010, 11). Simon Clarke and Nigel Melton then surveyed the site and identified only one burnt mound, which was most likely the northernmost one. The topography and layout of both burnt mound sites is very similar. Both sites are located at the entrance of streams that run down from the hills (Burn of Griesta and Burra Burn, respectively) into the heads of the valleys.

4.3.3 Tingwall Valley We will discuss the identified structures in the wider area by formal classes rather than attempt to classify them chronologically or order them geographically. 4.3.3.1 Burnt mounds Burnt mounds are a special type of prehistoric feature that occur throughout the British Isles (Buckley 1990; Hodder and Barfield 1991; Topping 2011). They are mostly crescent- or kidney-shaped heaps of firecracked stones that were used to heat water in a nearby trough and are therefore usually found along streams. Most burnt mounds date to the Bronze Age although some may be from the late Neolithic or Iron Age. Their function has been debated, and the interpretation of their function ranges from communal cooking sites or saunas to tanning or dyeing facilities. Four burnt mounds were identified in the lidar scan of Tingwall Valley, one of which appears to be a new discovery. The burnt mounds are grouped in two pairs on the north side of the lake. One pair is located north of the farm Griesta (Fig. 20). Both of these mounds were previously known8 (RCAHMS 1946, 124) and are marked on OS maps. The easternmost mound (HU 4155 4435) shows the typical crescent shape with the ends pointing towards the north, and it measures 17 m at the widest span. The second mound is located 75 m to the northwest (HU 4147 4438). The crescent shape is less clear in this case, but there is a central depression that faces south. With a diameter of 21 m, this is the largest of the four burnt mounds. 8

4.3.3.2 Enclosures The enclosures represent various types of structures and differ in function, size, shape and age. This group includes early modern “planticrubs” (small drystone enclosures that were used to shelter vegetable seedlings), animal pens and farmyards, and may also include prehistoric structures. The largest structure within this group consists of a shallow bank surrounding a knoll on the northwestern slope of Burra Dale on the northeastern side of the lake (HU 4226 4325) (Fig. 22C, 23). The oval enclosure measures approximately 40 m from north to south and 32 m from west to east. The bank appears as a rather subtle break in the slope to an observer on the ground. The structure is easier to identify in the lidar data than in the field. There are no signs of an entrance but the enclosure is transected by a subrecent ditch and fence. The enclosure lies approximately 24 m above the present water level of the Loch of Tingwall at a linear distance from the lakeside of approximately 150 m.

http://canmore.rcahms.gov.uk/en/site/1122/ (last accessed 2-12-2013).

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Fig. 22. Burnt mounds (A, B), a possible prehistoric enclosure (C), derelict drainage system (D) and peat banks (E) on the northern slope of Burra Dale. Local relief model overlaid on shaded relief (lidar data collected by the NERC ARSF in 2011).

The earthwork is located on the crest of a spur leading from the valley to the summit of Burra Dale and offers a splendid view of Tingwall Valley and Lax Firth. The location of the enclosure is referred to as “the Bunker” according to a place-name recording by the Shetland Amenity Trust. Unfortunately, there is no reference for this place-name. There is in fact a WWII bunker about 2 kilometres further south, near the lake Njugals Water. The place-name may therefore be mislocated or may perhaps reflect uncertain knowledge among locals during the war of the bunker’s top-secret location. However, it is unlikely that the newly discovered enclosure at Burra Dale has any connection with this hideout. The eroded state of the bank and the enclosure’s being transected by a fence that was first marked on the second edition of the OS 25 inch-to-the-mile map (sheet 052.11) that was published in 1901 imply that the enclosure must be older. It may be a prehistoric fortification, possibly a broch site, but this is a speculative interpretation that awaits further evidence. The name “Burra” (as in Burra Dale) deserves attention in light of this newly discovered enclosure. The Burra-element occurs several times in Shetland and mainland Scotland and is, among other explanations, considered a derivative of “broch” or the Old-Norse “borg” (Jakobsen 1897, 71).

Another intriguing enclosure, albeit of a very different nature, was detected near the summit of Gallow Hill on the western side of the valley (HU 4091 4262).

Fig. 23. Lidar scan of the enclosure at the northern slope of Burra Dale (see Fig. 22C). Local relief model, shading from white (positive) to black (negative), overlaid on slope map (lidar data collected by the NERC ARSF in 2011).

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Fig. 25. Rectangular enclosure (A), possible burial cairn remains (B) and medieval or early modern hill dyke (C) on Gallow Hill. The large clearance to the west (D) was recently made. Shaded relief overlaid on positive openness (lidar data collected by the NERC ARSF in 2011).

Fig. 24. Circular enclosure (A), medieval or early modern hill dyke (B) and its modern counterpart (C) on Gallow Hill. Shaded relief overlaid on slope map (lidar data collected by the NERC ARSF in 2011).

It is a circular enclosure, approximately 12 m in diameter, that is marked by an approximately 1 m-wide and 20 cm-high, fully overgrown drystone wall or earthen bank (Fig. 24). There seems to be an opening towards the northeast. The enclosure was discovered several years ago by Michael and David Leask of Asta (pers. comm. on 29-8-2013) but has not yet been recorded by archaeologists. The site is located on common grazing land, approximately 100 m from the old dyke in a depression on the Gallow Hill plateau. It is difficult to assert a function or date of the enclosure but its appearance and lack of being marked on historical OS maps may indicate a prehistoric or medieval origin. The enclosure could be an animal pen or ‘rett’ that may have been used to keep animals from the fields at night at a time before the inner field was fenced off with dykes (Tait 2012, 303f. and 319–23). The remains of a more recent sheepfold near the wind farm at Burra Dale are marked by a circular depression that is 16 m in diameter and is located partly outside the scanned area (HU 4218 4222). The sheepfold is marked on the first edition of the OS 25 inch-to-themile map (Sheet LII.11) that was published in 1880. Another structure was identified near the circular enclosure on Gallow Hill that is described above. This structure should be designated as an enclosure until we have further indication of its function (HU 4099 4243). It is a slightly trapezoidal structure of 8 × 6 m side lengths. It is built of large stones and appears to be open towards the west (Fig. 25). The stones may have been taken from a supposed prehistoric burial cairn that is located alongside it. The cairn is marked by a large concentration of loose boulders. Both the trapezoidal enclosure and the supposed cairn are located on the outside of an old dyke that surrounded the cultivated

land that is around the Loch of Tingwall. The structures are situated on the crest of Gallow Hill and offer a good view of the valley. Like the circular enclosure, the trapezoidal structure is not marked on the earliest OS maps, and its ruinous state suggests that it is relatively old. The structure seems rather small for an animal pen but fairly large for a building. One speculative interpretation is that it marks the site of the gallows, which may have stood at Gallow Hill until the second half of the 16th century (Coolen 2012, 13f.). If this is correct, the structure would be part of the judicial infrastructure that was associated with the Law Ting. The smallest enclosures can be interpreted as kale nurseries or “planticrubs” (Tait 2012, 440–447). Planticrubs (“krobbs”) were a ubiquitous element of the Shetland vernacular landscape from the Middle Ages until the 20th century. They were rectangular or circular with a diameter of a few meters and usually did not have an opening to prevent animals from entering. They are mostly found near the edge of (formerly) cultivated land on the western side of the valley in Tingwall. Planticrubs were often built on poorer land to prevent the kale seedlings from growing too well, which would complicate their transplantation. 4.3.3.3 Farms and settlements Remains of what may be prehistoric buildings were encountered on the Holm of Kirkasetter (HU 4157 4273), the Asta golf course (HU 4134 4196) and on the eastern shore of the Loch of Asta (HU 4137 4146). The structures at the Holm of Kirkasetter have been known since at least the 19th century and were initially interpreted as the remains of a medieval chapel. Upon a revisit of the site in 1968, it was stated that “there is no trace of this chapel which was situated on a turf

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croft at the eastern lakeside. The latter croft is locally referred to as the Cobbler’s house (pers. comm. Eileen Brooke-Freeman, 27-8-2013) or the Carpenter’s house (pers. comm. M. & D. Leask, 29-8-2013). This croft is very small compared to those on the western side of the valley and seems to have been the only farmstead on the eastern side of both lakes, which was historically an area with very poor and shallow soils. The croft can thus be considered a typical peripheral farmstead or utset that housed the poorest country dwellers in the 18th and 19th centuries (Tait 2012, 216ff.). The local name suggests that its residents were not entirely self-supporting and may have exchanged small craft services for food. Judging from the symbol on the first edition of the OS 25 inch-to-the-mile map published in 1880, the farmstead was deserted before the end of the 19th century. The remains of another small and ruinous farmstead marked on the OS map of 1880 between North and South Setter was vaguely apparent in the lidar data (HU 4133 4341). This may be the farmstead Walsetter, which appears in 17th and 18th century tax records but has not yet been located (Macgregor 1987, 365). A number of isolated, rectangular structures were identified throughout the scanned area. Some of these are also marked on the earliest OS maps. It is difficult to interpret these structures without further investigation on the ground because as they could represent large planticrubs, animal pens or shelters, or remains of buildings such as watermills or isolated dwellings. Conversely, some small ruins that are clearly visible on aerial photographs or in the field could not be identified in the lidar data, in part due to vegetation.

Fig. 26. Possibly prehistoric house site at the Holm of Kirkasetter (dashed line). The black line shows the present shoreline of the lake. The blanks south of the holm are erroneous readings caused by the reflectance of shallow water. Local relief model, shading from dark grey (positive) to white (negative), overlaid on shaded relief (lidar data collected by the NERC ARSF in 2011).

covered rocky knoll. The knoll is now much mutilated by quarrying“ (RCAHMS Canmore 1107). However, T. Watt and I. Tait (1996, 92) recorded a “circular house, with rampart at S face and two parallel walls at N, which converge. The latter two walls have been truncated by cultivation”. The lidar data seem to confirm this observation and clearly show the parallel walls but due to the dense shrubs the structure cannot be reconstructed in more detail (Fig. 26). A number of (sub)oval structures were detected that surrounding a rocky outcrop at the centre of the Asta golf course. No prehistoric finds have been reported from the site. Closer investigation on the ground would be needed to determine if the structures represent a prehistoric building cluster or natural features. The lidar scan reveals an oval structure, approximately 9 m long, on a small promontory on the eastern lakeside of the Loch of Asta. The structure has not yet been verified in the field but may well be the remains of a hitherto unknown prehistoric house. Most of the building remains that were detected in the lidar scan are croft buildings that date to the 18th or 19th centuries. The crofts North Garth (HU 4111 4254), Midgarth (HU 4109 4233) and a small croft on the eastern side of the valley between the Loch of Tingwall and the Loch of Asta (HU 4157 4183) are particularly well preserved. At North Garth and Midgarth, which are two deserted farmsteads at the slope of Gallow Hill, the typical elements of a 19th century croft can be identified in the lidar data (see Fig. 16). These elements include a walled yard with outhouses and storage pits for potatoes and kale (cf. Tait 2012). It is interesting to note that such structures are absent at the deserted

4.3.3.4 Land division and field systems The vast majority of features that were identified in the lidar scan are related to agricultural land use and land division. This group includes dykes and field boundaries, rigs and drainages. As in many parts of Northern Europe, agriculture in Shetland was (and still is) based on a division of the land into the intensively used land that surrounds the farms and settlements (tun) and the common grazing lands that lay beyond (skattald) (Tait 2012, 53f.). The tun was used for crop cultivation, hay-making and winter pasture, while the skattald provided grazing land and various resources such as peat, turf and game. This system of land-use dates back to at least the Middle Ages. The tuns were often enclosed by a dyke (fjalsgord) made of stone or turf to keep grazing animals out (Tait 2012, 55–59). While most hill dykes are believed to have been constructed in the late Middle Ages or early modern period (Tait 2012, 57f.), recent investigations have shown that prehistoric or Norse field boundaries were sometimes incorporated in later fjalsgords (Turner 2012). It is hence difficult to date such structures. Dating is further complicated

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because the hill dykes required constant maintenance and were sometimes extended, and many therefore exhibit multiple construction phases. Many dykes are still in use today, although the introduction of iron wire and the intensification of agriculture during the 19th century also changed the division of land and resulted in straight boundaries. The linearity of hill dykes thus provides a certain measure of their age because medieval or earlier township boundaries had a more irregular course (Turner 2012, 19ff.). This succession of the old meandering dykes and the later linear dykes and fences can also be observed in Tingwall. A well preserved irregular hill dyke runs along the slope of Gallow Hill at the western side of the Loch above the farms Asta, South-, Mid- and North Garth and South Setter (Fig. 24B, 25C), where it bends sharply towards the west to the Loch of Griesta (outside the scanned area). Above Asta and South Garth, a straight dyke runs parallel to the older one that is between 30 and 180 m further uphill. Further north, this dyke continues as a fence that was already marked on the first edition OS map of 1880 (Fig. 24C). From the opposite side of the Loch of Griesta, a meandering dyke runs north and describes a wide curve around Griesta and a deserted croft to the north, where it re-enters the lidar scan (Fig. 27A). It ends at the lowest point between the Hill of Griesta and Veensgarth and is marked both on old and modern OS maps. Interestingly, the lidar scan reveals a partially completed older part of the dyke that can be traced for a length of 180 m (HU 4148 4452–4167 4455) (Fig. 27B). It cuts off the bend around the deserted croft and aligns with the final stretch of the dyke, which suggests that the bend may be a later extension. As Tait (2012, 62f.) describes, most townships in Shetland were subdivided by internal dykes that enclosed the pastures of individual farms. Such dykes are indeed shown clearly on the image of Tingwall valley that was drawn by Thomas Woore in 1828 (see Fig. 5), but most of these internal dykes were removed in the 19th century. However, one example can still be seen near the Law Ting Holm. The field between the Law Ting Holm and Tingwall Kirk is surrounded by a derelict stone dyke that runs down to the lake and extends a short way into the water on both sides of the Holm. The direction of the dyke changes slightly at the former shoreline on both sides, which indicates that it was extended after the water level was lowered in the 19th century. The dyke most likely demarcates the pasture that belonged to the manse, and the high status of this holding may explain why this is the only field in the area that is (still) surrounded by a stone wall. The western part of Tingwall Valley is dominated by large pastures and meadows that have regular layouts. The present land division generally corresponds to the arrangement shown on the first edition of the OS maps and therefore dates back to at least the 19th century. The

Fig. 27. Medieval or early modern hill dyke north of Griesta (A). A tentative older part of the dyke (B) continues along the burn, cutting off a bend of the dyke around a ruined croft. Local relief model, shading from white (positive) to black (negative), overlaid on shaded relief (lidar data collected by the NERC ARSF in 2011).

pattern of large rectangular fields reflects the intensification of agriculture that took place during the 18th and 19th centuries. Tingwall may have been at the forefront of this development because it is one of the major agricultural areas in Shetland (I. Tait, personal communication 28-8-2013). The lidar scan reveals parallel rigs and furrows within many fields. Most align with the present field boundaries, and it is sometimes difficult to tell whether a linear groove represents a modern drain, a plough mark or an old rig boundary. The identifiable rigs all represent the straight type, which is also a relatively late development associated with the agricultural improvements of the 18th and 19th centuries (Halliday 2001, 18; Halliday 2003, 74). A particularly clear system of 18th or 19th century rigs can be observed around the deserted crofts at Mid- and North Garth. Some rigs appear in areas that are no longer under cultivation, such as the hill dyke at the southeast side of the Loch of Tingwall and the northern part of the Loch of Asta. Tentative remains of an older field system with narrower rigs and furrows were identified at the northern edge of the scanned area (HU 4165 4479). Cultivation of land in Tingwall Valley requires substantial draining. Drains can be observed in the lidar data throughout the scanned area and often reveal a pattern that is similar to that of the rigs. The densest drainage network can be observed in the northern part of the scanned area, in the boggy areas between the farm Griesta and Tingwall Kirk and towards Veensgarth. Many if not most of the identified drains are still in use and may be recent. However, the drainage pattern observed in the lidar scan obviously represents a palimpsest that covers several generations. In some areas, the drain pattern is similar to rig and furrow.

29

As improved drainage was indeed a major function of furrows, there is a sliding scale between these feature types. Like the field boundaries, the observed drainage network may be a result of land improvement in the 18th or 19th century. However, a more irregular drainage system was encountered in the scattald on the eastern lakeside (Fig. 22D). The repeating pattern of drains and streams suggests that they are at least partly manmade and may therefore represent a much older drainage network that has been overgrown by nature. This in turn implies that the west-facing slopes at the eastern lakeside may have been cultivated at some time in history.

improvement of agriculture in the 20th century, landscape elements of the preceding period are still visible. The scan has revealed patterns of rig and furrow and various derelict croft buildings that were hitherto unknown. The drawback of the intensive cultivation of Tingwall Valley over the past centuries is that pre-modern structures are likely to have been destroyed or are at least not visible at the surface (cf. Halliday 2001, 10f.). This applies particularly to the improved areas to the north and west of the Loch of Tingwall. Unfortunately, this is the area in which the assembly is said to have taken place. It is therefore perhaps not surprising that no structures could be identified in the lidar scan that can be associated directly with the assembly site. The lidar scan reveals remarkably little about the Viking Age and medieval land use. However, once again, the absence of evidence is not evidence of absence. It is widely accepted that there was a large degree of continuity in the way the subsistence economy and the landscape were organised in Shetland from the Viking Age until well into the so-called crofting period (Smith 2000; Tait 2012, 45–54). This is reflected, for example, by the names of the main farms around the Loch of Tingwall reflecting Norse settlement structures (Macgregor 1987, 361–372). It is therefore quite likely that the settlement areas of the Norse and medieval period remain buried beneath today’s cultivated areas. Furthermore, we must recall that lidar reveals only structures that are marked by height differences at the surface. Nevertheless, the lidar survey has shown that Tingwall has a rich cultural landscape, in which many elements of the vernacular (Tait 2012) and prehistoric site types are well preserved. The method has proven effective for archaeological prospecting in Shetland, and further lidar scans would no doubt show that Shetland’s archaeological heritage is even much richer than has hitherto been recognised.

4.3.3.5 Extraction sites Raw materials that were locally exploited include peat and limestone. Extensive traces of peat cutting were observed northeast of the Loch of Tingwall, on the slopes of Burra Dale (Fig. 22E). With depths of less than 50 cm, and at some points of even less than 20 cm, the peat cuttings are exceptionally shallow despite some peat regeneration that has occurred since the last extraction. It also seems unlikely that the relatively welldrained slopes in this area contain deep peat deposits. These peat banks would therefore have yielded a rather low quality fuel, but may have been used to procure building turf (Tait 2012, 119f.) or turf mould, which was used as animal bedding (Tait 2012, 305ff.). The lidar scan reveals a number of quarries, some of which are marked on the late 19th century OS maps. Three of them are associated with a lime kiln. Two lime kilns are situated on the slope of Gallow Hill above Kirkasetter (HU 41207 42767; HU 41178 42674). They are both marked on the first edition of the OS map as “old limekilns”. The third kiln, which is also marked but not described on the first OS series and thus may have been in use in 1880, is located at North Setter (HU 41347 43620). 4.4 Discussion The landscape of Tingwall Valley bears traces of several thousand years of human activities, from at least the Bronze Age until today. These traces can be identified nearly everywhere in the lidar scan. Because of its geographic location and its rich grazing land, fertile soils, and freshwater lakes, Tingwall has been one of the most thriving and prominent agricultural areas in Shetland. The present landscape of Tingwall Valley was shaped primarily in the 18th and 19th centuries. Although this is not a revolutionary insight, the lidar scan shows that the 19th century landscape, including crofts, dykes, animal pens and field systems, is much better preserved than it first appears. Despite the continuing intensification and

4.5 Acknowledgements The authors would like to thank Alexandra Sanmark and the Airborne Research and Survey Facility of the Natural Environment Research Council for providing the lidar data. We are most grateful to the Shetland Amenity Trust for providing a grant for additional fieldwork and to the dedicated Trust staff, especially Eileen Brooke-Freeman, Chris Dyer, Brian Smith, Ian Tait and Val Turner, for their support and discussion of some of the identified structures. Last but not least, we would like to thank Neil Anderson and Michael and David Leask for sharing some of their knowledge of the local history and landscape of Tingwall.

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Fig. 28. Outline of trench 1 and 2 overlain on the geomagnetic survey data (background map © Crown Copyright/database right 2010. An Ordnance Survey/EDINA supplied service).

5

Excavation Methods

5.1 Location of trenches Both the geomagnetic survey and the various historic accounts of the site raised several questions which could only be answered by excavation. However, due to restricted time and the protected state of the scheduled monument excavating the entire holm, which covers more than 525 m², was not an option. So far, only few excavations have been carried out at North European assembly sites, and as far as we know, none of these concerned the actual place where the judges were said to have met. Hence, no other archaeologically investigated site could help us choose the most rewarding spot for an excavation. The main trench, trench 1, is located on the holm (Fig. 28). In consultation with Historic Scotland, it was agreed to excavate the northwestern quarter of the holm, the planned size of the trench being 12 × 12 m. The location of the trench was chosen under the following objectives: - Although the main focus of the assembly site might rather have been on the highest part of the holm, the bedrock, which partly protrudes from the surface in this part, suggested a very shallow soil

cover and minimal stratigraphy.9 It was hoped that the northern and lower part would offer a thicker soil cover and better preserved stratigraphy. - The geomagnetic survey had revealed a number of highly magnetised anomalies of up to 2 m diameter in the northwestern part of the holm, the nature of which was to be clarified by excavation. - In its originally planned extent, the trench would have included the junction of the causeway and the holm. The excavation should verify if the entrance of the holm was marked by any distinct features, as suggested by the original RCAHMS survey record. In the ideal case, it would be possible to link the causeway to the stratigraphic sequence of the holm, allowing for stratigraphic dating. - Although not the ideal location to clarify these questions individually, the initially scheduled trench might reveal the nature of both the linear, This assumption proved to be wrong as a benchmark was put at the top of the holm during stakeout; the metal rod driven into the ground suggests that the bedrock is buried by at least 40 cm of soil in some places. 9

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negative anomaly at the (south)western edge and the double, linear, positive anomaly along its north(east)ern side. The former was believed to represent the possibly modified bedrock face, while the latter is obviously caused by an accumulation of positively magnetised material and might represent the fill of a double ditch or a wall or bank of igneous rocks or rocks containing a high amount of iron-oxides. - The trench included a large, heavily weathered quartz outcrop near the centre of the holm, partly protruding from the surface and visible as a negative anomaly in the geomagnetic data. The excavation should clarify if the rock was artificially modified and if it was fire cracked or naturally weathered. - Excavating one quarter of the holm allowed for the study of both the centre and the side of the holm, both of which may theoretically have played a special role in the assembly practice. It was decided to start with trench 1 by opening the eastern half of it (6 × 12 m). This turned out to be a fortunate decision, since even this reduced trench could not be fully excavated in four weeks due to the complex stratigraphy and the large amount of artefacts. However, it also meant that some of the research questions addressed above could not be answered, as their focus lay beyond the extent of

Fig. 29. Outlines, spot heights and the position of special finds were measured with a total station connected to a laptop (photo R. Weßling).

the actual trench. Unless indicated otherwise, “trench 1” will hereafter refer to the excavated part – the eastern half of the initially planned trench – only. Trench 2 is located in the central part of the causeway, where both faces are well preserved, and where the geomagnetic survey had revealed a strong, bipolar anomaly caused by a ferrous object. The trench measured 4 × 1.5 m and was laid out across the causeway to

Fig. 30. Surface models of [C1005]. Vertical exaggeration 1.5×, with trench grid overlain: A – TIN calculated from spot heights and outline measured during the excavation; B – Orthophoto draped over the TIN; C – DEM calculated from overlapping photographs; D – True orthophoto draped over the DEM. 32

provide a cross section. Apart from the construction of the causeway and the nature of the ferrous object at its centre, it was hoped that the trench would yield more information on the causeway’s age.

the computer. Measured points, lines and polygons appear in the AutoCAD drawing and can be grouped into different layers, avoiding the need to encode and export the measurements from the total station. The top and bottom interfaces of each stratigraphic layer were recorded separately to enable three-dimensional (3D) reconstruction (cf. Doneus and Neubauer 2004). Because each bottom interface corresponds to (part(s) of) the top interface of the layer(s) below, the former is, in fact, redundant. It was, however, considered more efficient and precise to record the bottom interface on site than to subsequently extract it from the underlying top interface. After the excavation, the CAD drawing was exported to a Geographic Information System (GIS), which offers better opportunities for spatial analysis and mapping. The spot heights and outline of each layer interface were used to create a 3D TIN (Triangulated Irregular Network) model (Fig. 30A), which, in turn, allows for the volumetric reconstruction of the excavated contexts.

5.2 Excavation and documentation methodology The excavation and documentation strategy of the Law Ting Holm excavation have been detailed in the Data Structure Report (Coolen and Mehler 2011, 13–16 with appendices). The following is a summarised and updated version of this text; for additional information please refer to the Data Structure Report. In accordance with current standards in British archaeology, the excavation was conducted in stratigraphic units with single context documentation. Each stratigraphic layer, including its top and bottom surface (layer interface), was analysed as one context. Contexts were numbered from [C1000] in trench 1 and from [C2000] in trench 2. To facilitate the localisation of features and bulk finds, trench 1 was divided into a 1×1 m grid. The grid cells were labelled A–L from west to east (only G–L were excavated) and 100–111 from south to north. This division had no effect on the excavation process itself (i.e., excavation did not take place in individual grid units), but bulk finds and flotation samples were collected per grid cell within each stratigraphic context. The entire excavation was done by hand, using trowels, mattocks and spades. At the end of the excavation, both trenches were covered with geomembrane to protect the remaining stratigraphy and to guide potential future excavation. Trench 1 was backfilled with an excavator; the grass sod was replaced manually. Trench 2 was backfilled by hand. Special care was taken to reconstruct the causeway, but reconstructed parts were placed on top of the geomembrane to differentiate these parts from original elements.

5.2.2 Photographic documentation Photos were taken with a 12.2 megapixel single-lens reflex digital camera (APS-C sensor format) with an 18–55 mm zoom lens. Apart from the regular, oblique photos taken from the ground, elevated photos were taken using a monopod or, for photos up to 11 m above ground level, an extendable camera crane designed and built by one of the team members (Krenn-Leeb et al. 2012) (Fig. 31).10 The camera’s suspension allowed for adjustment of the camera angle, so vertical and oblique photographs could be taken. The camera shutter was remotely released; a video downlink allowed the photographer to see where the camera was pointing. To avoid the laborious task of drawing layer surfaces and stone scatters by hand, orthophotos of each layer surface were created (cf. Doneus and Neubauer 2004). For this purpose, every documented surface was photographed vertically with at least four measured reference points (copper nails or paper targets) along the edges of the frame. The reference points allow for the geometrical correction of the image in one horizontal plane, resulting in a georeferenced orthophoto with minimal geometrical distortion (Fig. 30B). Prior to the geometrical correction and georeferencing, the photos were corrected for lens distortion and chromatic aberration using the software PTLens 8.7.8. Orthorectification and georeferencing were performed with the plug-in Kubit PhoToPlan 5.0.1.6 for AutoCAD. To document the larger surfaces, multiple photos had to be individually rectified and stitched together. In some cases, the contrast and brightness of adjacent photos had to be adjusted in Adobe Photoshop in order to seamlessly blend the photos together.

5.2.1 Excavation survey Context outlines, spot heights and the position of special finds were measured with a total station. The excavation survey was tied to the OS national grid using three benchmarks (TBM 01–03), which had been established by a commercial surveyor prior to the geophysical survey in 2010. For convenience, four additional benchmarks were marked closer to the excavation trenches (TBM 04–07). Because the ODN heights of TBM 01–03 were unknown, relative heights were used during the excavation. These relative heights were later corrected with the height values of two of the initial benchmarks, which were measured with RTK DGPS after the excavation. The total station was attached to a laptop running AutoCAD® 2009 with the plug-in Kubit TachyCAD (Fig. 29). This plug-in facilitates direct communication between AutoCAD and the total station; both stationing and measuring can thus be controlled from

http://www.unet.univie.ac.at/~a0847161/pap-pole-aerial-photography/photokran-opterix (accessed 18 October 2013)

10

33

Fig. 32. Detail of [C1005] showing the difference between projective (above) and true orthorectification (below). Note the visible trench profile and the lateral shift of the stones on the right side.

Fig. 31. The camera crane Opterix 2.0 in use during the excavation of trench 2.

The past few years have seen a rapid development of computer vision techniques, which can be used to create 3D-models from overlapping photographs using Structure from Motion (SfM) and Multi-View Stereo (MVS) algorithms. This method offers great potential for stratigraphic recording, largely because it can be achieved with any regular camera and free or low-cost software (Doneus et al. 2011; De Reu et al. 2013; Weßling et al. 2013). Although the photographic documentation of the excavation at the Law Ting Holm was not originally intended for this purpose, the photos can still be used to create models. The stereo-vision approach offers several advantages over the method described above. First, it results in a 3D-model with a much higher resolution than the TIN created from the manually recorded spot heights (Fig. 30C). The reference points on the photos can be used to georeference the model. Second, the 3D-model can be used to create a true orthophoto, where the pointcloud is used to calculate the planimetric shift of every pixel (Fig. 30D). While PhoToPlan distorts the original image to match the reference points, the stereo-vision method computes a new orthorectified image based on the information derived from the original images. This method results in a more exact orthophoto, especially for complex surfaces with steep vertical drops (Fig. 32).

The application of SfM and MVS algorithms on photos taken during the Law Ting Holm excavation demonstrates that these modern techniques can be applied to older photographic records that were not originally created for this purpose (cf. Grün et al. 2004). However, the suboptimal alignment (insufficient overlap or incomplete coverage) and blurriness of some images resulted in rather noisy or inaccurate surface models. The elevation models and volumetric calculations in chapter 6 are therefore based on the TINs created from the original survey data rather than the SfM/MVS technique. 5.2.3 Recovery of finds and sampling All recovered deposits were dry-sieved on a 2.5 × 1.3 cm mesh. As mentioned before, bulk finds were collected per context and grid square. Each find unit was assigned an individual number (FN) and recorded in a find list on site, which provided the context, grid unit and a short description. Special finds (SF) were given a separate number and measured with the total station. Pottery, bones and stone artefacts were cleaned and the finds were sorted by category at the excavation quarters. All finds (except shells and whelks) were counted and recorded in a find list that could later be linked to the spatial information recorded during the excavation to analyse the distribution of find classes or to map the original position of individual find numbers.

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Fig. 33. Context plan of the topsoil layer [C1000] showing the location of special finds and the morphology of the top surface at the start of the excavation (5 cm-contours). The scale is indicated by the 1m-trench grid.

6

Results from the excavation

6.1 Trench 1 The original surface of trench 1 rose from 9.4 m above sea level in the north to 10.3 m in the south (Fig. 33). All excavated contexts generally followed the same slope direction, which seems to be determined by the surface of the underlying bedrock (although the latter was not fully excavated). The topsoil layer [C1000] was 8 to 20 cm thick (Table 2) and consisted of peat with a high content of sandy loam. It was manually removed in large sods, which were put back after the excavation. Numerous finds were recovered from the topsoil, already indicating the richness of the underlying deposits. Among the finds were a clay pipe fragment (FN008), several pieces of post-medieval pottery (FN001, FN005, FN009, FN010, FN049) and roof slate fragments (FN001), as well as a large number of animal bones, prehistoric pottery, stone artefacts and slags. [C1000] contained only few shells compared to the underlying deposits, which may be due to the worse conditions for their preservation in the topsoil. With the exception of the south-eastern corner, where an outcrop of weathered quartz protruded from the original grass cover, the layers underlying [C1000] consisted entirely of anthropogenic deposits. [C1001] refers to the fill of a shallow depression in grid squares J–K 103–5 (Fig. 34). [C1001] was loamier, slightly lighter in colour and contained fewer stones than the underlying context. It contained charcoal and several finds, including a post-medieval glass fragment (FN111) (Fig. 35). The depression measured approximately 2.5 × 1 m and was up to 8 cm deep. However, the interface was not very clear. [C1001]

Area (m²)

Volume (m³)

Trench 1 C1000 C1001 C1002 C1003 C1004 C1005 C1006 C1007 C1008* C1009 C1010 Sum

71.24 2.06 5.78 0.11 69.86 44.29 11.94 9.24 0.14 0.41 47.03

8.99 0.06 0.05 < 0.01 3.89 2.66 0.5 0.5 < 0.01 0.06 2.75 19.47

Trench 2 C2000 C2001 C2002 C2003 C2004 C2005 Sum

5.25 1.38 1.21 no data no data no data

0.89 0.04 0.13

1.06

Table 2. Area and volume of the excavated contexts. (* C1008: Estimated value, bottom interface not recorded.) 35

Fig. 34. [C1001]–[C1003]. Orthophoto with 5-cm-contour lines showing the morphology of the top surface.

seems closely related with the lower topsoil, and may in fact have represented a zone of mixed material at the interface between the topsoil and the underlying deposit. The same probably applies to [C1002], a very shallow humus deposit along the western profile in G104–H108. It appeared as a largely stone-free zone of about 4.8 × 1–1.8 m width. However, as shall be discussed below, this context may be the upper part of a poorly recognised, underlying feature. [C1002] came off to a layer of fine gravel instead of the expected coarse cobble stones which mark the surrounding area. [C1002] yielded a considerable amount of (bulk) finds, which is remarkable given the small volume of the context. The majority of finds is of prehistoric age.

[C1003] was a thin gravel layer in the south-eastern corner of trench 1. Its texture was notably different from the topsoil and the underlying layer, but given its limited extent (an unknown part of the context stretching beyond the excavated trench), it is hard to interpret. [C1003] yielded a few post-medieval pottery fragments (FN099). [C1001], [C1002] and [C1003] all came off to [C1004], a layer of dark brown, sandy loam with many scattered stones of up to 20 cm diameter. [C1004] covered the whole trench but appeared rather heterogeneous (Fig. 36). Although differences in texture, density of inclusions and soil colour were noticed within the context, none of these were sufficiently clear to be identified as individual contexts. However, as

Fig. 35. Distribution of (special) finds in [C1001]–[C1003]. 36

Fig. 36. [C1004]. Orthophoto with 5-cm-contour lines showing the morphology of the top surface.

mentioned above, the area below [C1002], which was marked by a high gravel content, may in fact have been part of a separate feature (feature 1). The area G104–8 formed a clearing in the mostly dense stone scatters of the sequential contexts from the first documentation level down to the bottom of the excavation, and the high gravel content was still observed at the lowest level. The extent of [C1002] largely corresponds with the marked contexts [C1015], [C1016] and [C1017], which were observed at the final documentation level (see below). In hindsight, these contexts may be considered as different fills of the same feature, in which case this feature would have a high position in the matrix, directly underlying the topsoil.

In general, [C1004] was less than 10 cm thick. Nevertheless, it represents the most voluminous context that was excavated apart from the topsoil layer [C1000]. [C1004] can be interpreted as a midden deposit. With a total number exceeding 2,500 individual finds, [C1004] yielded most finds of all excavated contexts. Among the special finds are a perforated stone disk (SF126), a steatite spindle whorl (SF181), a copper alloy ringlet (SF231), a stone bead (SF258), several pieces of pumice, various stone artefacts and decorated pottery fragments. Bulk finds mainly comprise animal bones (representing almost two thirds of all finds), followed by pottery and metal slag. The bones were scattered throughout the entire context (Fig. 37),

Fig. 37. Distribution of bones and bone fragments in [C1004]. 37

Fig. 38. Distribution of burnt bone fragments in [C1004].

Fig. 39. Distribution of pottery fragments in [C1004].

Fig. 40. Distribution of slags and metal finds in [C1004]. 38

with an exceptional high number in grid square G101. Many bones show traces of burning (see Chapter 9.4.4). The burnt bones concentrated towards the south-western corner of the trench (Fig. 38). By contrast, the pottery fragments show a slight concentration in the northern half of the trench (Fig. 39). Metal slag was mainly found in the southern half of the trench (Fig. 40). [C1004] also contained a large number of oyster and cockle shells and whelks; interestingly, these were only found in the southern part of the trench (Fig. 41). The shells and whelks were found in small concentrations and usually embedded between cobbles. Stone artefacts were scattered throughout the context (Fig. 42). During the excavation of [C1004], small lumps of what appears to be burnt organic matter were encountered

in larger numbers. Similar pieces were also found in underlying contexts and systematically collected. In [C1004], such lumps were only found in the southwestern diagonal half of the trench (Fig. 43). The finds might be fragments of burnt peat but this could not be clarified. While obviously organic, the material is rather homogenous and fine-grained. Some pieces are partly vitrified, while others are merely blackened. After the removal of [C1004], a dense stone scatter appeared in most parts of the trench. Several contexts were distinguished in the underlying surface. [C1005] was described as a layer of dark brown, sandy soil containing a large amount of gravel and cobbles, covering the eastern and central part of the trench (Fig. 44). [C1005] was equally rich in finds as [C1004]. Both the composition of the assemblage and the distribution of

Fig. 41. Distribution of shells and whelks in [C1004].

Fig. 42. Distribution of stone artefacts in [C1004]. 39

Fig. 43. Distribution of burnt organic matter in [C1004].

Fig. 44. [C1005]. Orthophoto with 5-cm-contour lines showing the morphology of the top surface.

Fig. 45. Distribution of bones and bone fragments in [C1005]. 40

finds were very similar, indicating a close genetic relationship between both contexts (Fig. 45–51). Special finds from [C1005] include a bronze wire spiral (SF361) and several stone tools. Separate concentrations of larger stones were observed in the southern and northwestern corner of trench 1. These concentrations were recorded as [C1006] and [C1007] respectively (Fig. 52). [C1006] formed an L-shaped concentration of larger boulders (up to 40 cm diameter) in the southwestern corner of the trench. Apart from a small overlap in J–K 102, it was separated from [C1005] by a square clearing in I–J 102–4, formed by a low rise in the underlying layer surface. The stratigraphic relationship of [C1006] and [C1005] was therefore not evident. Finds from [C1006] mainly

comprised bones (Fig. 53), shells and whelks (Fig. 54). The latter were already seen to concentrate in the southern part of the trench in [C1004]. A concentration of metal slag was found in J101 and the adjacent grid squares (Fig. 55). This also corresponds to the spatial distribution observed in [C1004]. [C1006] contained only few pottery fragments (Fig. 56), stone artefacts (Fig. 57) and lumps of burnt organic matter (Fig. 58). [C1007] had a very similar appearance as [C1006] and contained equally large boulders (see Fig. 52). Although the interface outline was originally recorded parallel to the interface of [C1005], the later clearly overlay [C1007]. Numerous bones and a few pottery fragments, as well as a quern rubber fragment (FN402) were retrieved from this context (see Fig. 53–58).

Fig. 46. Distribution of burnt bone fragments in [C1005].

Fig. 47. Distribution of pottery fragments in [C1005]. 41

Fig. 48. Distribution of slags and metal finds in [C1005].

Fig. 49. Distribution of shells and whelks in [C1005].

Fig. 50. Distribution of stone artefacts in [C1005].

42

Fig. 51. Distribution of burnt organic matter in [C1005].

Fig. 52. [C1006]–[C1007]. Orthophoto with 5-cm-contour lines showing the morphology of the top surface.

Fig. 53. Distribution of bones and bone fragments in [C1006]–[C1007]. 43

Fig. 54. Distribution of shells and whelks in [C1006]–[C1007].

Fig. 55. Distribution of slags and metal finds in [C1006]–[C1007].

Fig. 56. Distribution of pottery fragments in [C1006]–[C1007].

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Fig. 57. Distribution of stone artefacts in [C1006]–[C1007].

Fig. 58. Distribution of burnt organic matter in [C1006]–[C1007].

As [C1005] was removed, an underlying stone setting appeared in grid square L102 (Fig. 59). After the excavation, the setting was termed feature 2. It consisted of several stone slabs forming a circle with an outer diameter of approximately 1 m and an inner diameter of approximately 40 cm. The slabs were partly put one on top of the other, constituting a low wall of 30–40 cm height that was recorded as [C1009] (Fig. 60). [C1009] was set against the bedrock outcrop in the southeastern corner of trench 1. It was stratigraphically overlain and hence separated from [C1005] by a layer of dark brown sandy clay loam with cobbles, [C1008] (see Fig. 60), which covered the space between the stone setting and the bedrock and filled the cracks in the weathered rock. [C1008] could be interpreted as intentional backfill between the stone setting and the rock for greater support, but it needs to be stressed that the material was very similar to [C1005]. [C1008] yielded a few bone fragments, metal slag and one shell.

The stone setting, [C1009], was most distinct on the north side, where a flat slab of approximately 30 × 20 × 5 cm overlay a large, rectangular slab of approximately 50 × 30 × 20 cm. Both slabs extended into the profile and were left in situ. On the south side, [C1009] consisted of smaller stones and had largely collapsed. The bottom of the setting was formed by densely spaced stones of up to 25 cm diameter. Since the structure was not dismantled, it is not clear whether these stones constituted an intentional surface at the bottom or whether they were part of an underlying deposit. [C1009] is very likely an intentional stone setting but its function is not clear. Feature 2 was initially interpreted as a stone lined pit (Coolen and Mehler 2011, 21). However, as the stratigraphic observations made during the excavation indicate that the stone setting was a free-standing rather than a sunken feature, the term pit seems not appropriate anymore. Hence, feature 2 cannot be seen in context with any other structures as yet. 45

Their find spots lay outside the recorded outline of [C1010]. These finds are, in fact, cleaning finds from the next underlying deposit which was not excavated. Apart from the red mottles, [C1010] appeared similar to the large contexts that overlay it. [C1010] contained many mostly sharp-edged stones, including some boulders of up to 50 cm diameter. A large granite (?) boulder, which was found at the border of grid squares I–J 104–5, had a smooth concave face that may have been worked (FN471) (see Chapter 8.4.1.2). In the area surrounding grid square J106, the stone scatter appeared less dense at the upper surface of [C1010]. This clearing became more distinct towards the bottom surface of the context. In most places, [C1010] was no more than 5 cm thick. The find assemblage from this context is similar to that of [C1004] and [C1005], but [C1010] did not yield as

Fig. 59. [C1009] (feature 2): stone-setting in grid square L102.

Fig. 60. [C1008]– [C1009]. Orthophoto with 5-cm-contour lines showing the morphology of the top surface.

many finds. Most notably, [C1010] contained significantly fewer pottery fragments than the former contexts. Special finds from [C1010] include two tubular bone artefacts (SF435, SF446). Human bones, including parts of a skull (FN465), were found in close proximity in grid square L108 (Fig. 62). The bones belong to a 2–3-year old child (see Chapter 10). Interestingly, some of the bones that possibly belong to the same individual were found somewhat higher in [C1004] in the adjacent grid square L109 (FN232). Animal bones mainly concentrated in the northern part of [C1010] (Fig. 63). A concentration of burnt bones was found in grid square G101 (Fig. 64). Iron slags were mainly found in the southern part, with an apparent isolated concentration in grid square J107 (Fig. 65).

In the upper part of the trench, [C1005] came off to a dark brown layer of sandy loam, [C1010], which was distinguished from the former by red peat ash mottles and a lower content of stones (Fig. 61). The peat ash mottles were most dense in the southwestern quarter of the trench (where patches of peat ash were first observed during the removal of [C1004] and hence seem to be associated with the underlying features 3 and 4 (see below). They were less frequent or clear in the lower parts of the trench along the eastern profile and in the northern half. Therefore, [C1010] was not recorded in these areas as the outline was not clear. Some finds from grid squares K–L 105–6 and G–L 110–11, which were recovered during the final cleaning of the trench, were erroneously assigned to [C1010].

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Fig. 61. [C1010]. Orthophoto with 5-cm-contour lines showing the morphology of the top surface. Shells and whelks appeared in all parts of the context but showed a slight concentration in the south (Fig. 66), whereas pottery fragments (Fig. 67), stone artefacts (Fig. 68) and tentative peat coal fragments (Fig. 69) did not show any significant concentration at all. At the southern edge of the trench (grid squares I–L 100–1) [C1010] came off to a natural gravel layer, presenting the eroded bedrock surface (Fig. 70). However, [C1010] overlay several archaeological contexts and features in the lower parts of the trench (Fig. 71). Unfortunately, they were merely uncovered but could not be fully excavated due to restricted time. Hence, the contexts underlying [C1010] and their stratigraphic relationships could not be studied in detail and the features are difficult to interpret.

Fig. 62. Parts of the skull of a 2–3-year old child that were found in [C1010] (L108).

Fig. 63. Distribution of bones and bone fragments in [C1010]. Finds from the hatched squares were erroneously assigned to [C1010]. 47

Fig. 64. Distribution of burnt bones and bone fragments in [C1010]. Finds from grid square K111 (hatched) were erroneously assigned to [C1010].

Fig. 65. Distribution of iron slags in [C1010]. Finds from the grid square K111 (hatched) were erroneously assigned to [C1010].

Fig. 66. Distribution of shells and whelks in [C1010]. Finds from the hatched squares were erroneously assigned to [C1010]. 48

Fig. 67. Distribution of pottery fragments in [C1010]. Finds from the hatched squares were erroneously assigned to [C1010].

Fig. 68. Distribution of stone artefacts in [C1010]. Finds from the hatched squares were erroneously assigned to [C1010].

Fig. 69. Distribution of burnt organic matter in [C1010]. Finds from the hatched squares were erroneously assigned to [C1010]. 49

Fig. 70. Final documentation level after removal of [C1010]. Orthophoto with 5-cm-contour lines.

Fig. 71. Orthophoto of the final documentation level with the outline of [C1011]– [C1020] as recorded on the last day of the excavation. [C1011] is a large, L-shaped peat ash deposit measuring approximately 2.5 × 3 m that was encountered in the southwestern corner of the trench (grid squares G–H 101–3) (Fig. 72). Single patches of peat ash had been observed at the higher documentation levels in this area. The peat ash mottles were initially regarded as inclusions in the overlying layers but in fact presented the upper part of [C1011]. The context corresponds to a large, positive magnetic anomaly encountered during the geomagnetic survey (Fig. 73). Although the

context was not fully excavated, several archaeomagnetic dating samples were taken by Zoe Outram (see Chapter 7). As the total extent of the deposit was not yet clear at the time of the sampling, all samples were taken in square G101. The scattering of the magnetic orientation of the samples suggest that [C1011] was not burnt in situ but may represent a dump of ash (see Chapter 7.4). The ash deposit of [C1011] included small pieces of burnt bone as well as charcoal. A number of bone

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Fig. 72. Peat ash deposit [C1011].

Fig. 73. Outline of peat ash deposits [C1011], [C1012], [C1016] and [C1017] overlain on the results of the geomagnetic survey (dynamic range from white to black: -26.7 / 28.2 nT). The peat ash deposits are marked by strong positive anomalies.

fragments were recovered. The context had a very uneven surface, with numerous slots and cavities of up to 8 cm deep. Some of these may have been formed as stones from the overlying deposits were pressed into the soft deposit. However, most of them were filled with dark, sandy material from the overlying contexts and may thus present the original surface. Another peat ash deposit, [C1012], was encountered in the central part of the trench. [C1012] lay slightly higher than the surrounding area and covered a rectangular area of approximately 1.7 × 1.5 m surrounded by sharp-edged stones of up to 30 cm diameter (Fig. 74). The feature, which was later termed feature 3, can be interpreted as the remains of a hearth or kiln. [C1012] had an orange colour along the sides but was rather light brown to greyish at the centre. The change in colour may be caused by a gradual heat difference from a central fire and suggests that the deposit was in situ. 30 samples were taken for archaeomagnetic dating (see Chapter 7.5). The burnt material of [C1012] was

observed as a strong, positive anomaly in the geomagnetic survey (see Fig. 73). [C1013] was originally defined as a reddish to dark brown fill between and under the stones to the north of feature 3. The stone rubble covering the entire northern half of the trench (possibly underlying all other contexts) was marked as [C1014]. However, it was realised during the final cleaning that [C1013] and [C1014] should probably be considered as one context. On the other hand, several concentrations and alignments were observed within the rubble of [C1014], indicating that this context may represent multiple deposits. None of these could be sufficiently distinguished to be termed individual features or contexts. Two converging stone alignments in grids J–L 107–8 were termed feature 4, but this feature could neither be clearly distinguished from the rest of [C1014], nor readily interpreted. The alignments diverged by about 40° from north to south, opening out to a depression in the excavated surface covered by [C1019]. The gully

Fig. 75. [C1016]–[C1017] (feature 5): peat ash deposit in grid squares G 106–8. Fig. 74. [C1012] (feature 3): tentative hearth in grid squares H–I 104–5.

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between the two stone alignments was approximately 25 cm deep at the narrower northern end. The easternmost stone alignment presented a distinct edge. It could be recorded over a length of approximately 3 m but it may still extend further east beyond the trench. The western alignment was less distinct but could still be recognised over a length of 1.3 m. Although feature 4 most likely represents an intentional man-made feature it cannot be readily interpreted. Feature 4 may well have been part of a larger structure which could not be recognised yet and may extend beyond trench 1. To the west of feature 3, [C1010] came off to a layer of medium brown soil with a high gravel content [C1015]. [C1015] presented a semi-circular feature, which probably extends further west beyond the excavated trench. It was framed by dense stone rubble to the south and north. To the east, [C1015] was bordered by the stones at the base of feature 3. [C1015] may well be part of the poorly recognised feature along the western profile discussed above (feature 1), as its location corresponds to the gravel layer noted already after the removal of [C1002]. In this case, [C1015] would be stratigraphically younger than the surrounding stones and cut through [C1014]. The latter also applies to feature 5, which was observed to the north of [C1015] in squares G 106–8. This feature comprises two contexts, [C1016] and [C1017] (Fig. 75). Both contexts seem to be part of a circular feature of approximately 3 m diameter, the larger part of which seems to lie beyond the excavated trench. [C1016] consisted of a band of dark red peat ash surrounding [C1017]. [C1017] consisted of beige, sandy loam with a high gravel content. The mutual interface of both contexts is marked by a number of stones, again forming a semi-circle. Although [C1017] was slightly higher than [C1016], the latter seemed to be stratigraphically younger. Since neither of them was excavated, it is not clear to which context the stones at the interface between [C1016] and [C1017] belong. The stones might as well be part of the underlying deposit, possibly [C1014]. The location of [C1016] and [C1017] is marked by a bipolar, magnetic anomaly in the geomagnetic survey (see Fig. 73). The anomaly may have been caused by the positively magnetised peat ash of [C1016] and the apparently negatively magnetised material of [C1017]. However, the anomaly does not extend to the west of the trench. Like [C1015], [C1016] and [C1017] may also be linked with feature 1. The location of feature 5 was already marked by a somewhat larger semi-circular clearing after the removal of the top soil. However, since [C1016] and [C1017] were only partially uncovered, we do not dare give any interpretation of its former function at present. [C1018] was originally described as the continuation of [C1010] at the northern side of the trench. Its texture was considered similar to [C1010] except for peat ash mottles. However, the distinction between

[C1018] and [C1010] on the one hand and [C1014] on the other hand seems rather problematic, especially because the context was not fully excavated. For this reason [C1014] and [C1018] were later considered as one context, providing that [C1014] may have to be divided into several contexts upon further excavation. While the bottom of trench 1 was still largely dominated by stone rubble at the final documentation level, the lowest part of the trench, along the eastern profile, was covered by a loamy, medium brown deposit containing fewer and smaller stones [C1019]. Its stratigraphic relationship to [C1014] could not be clarified. An oval shaped deposit of light, greyish brown silt loam with a high gravel content, apparently overlaying [C1014], was observed in grid squares J–L 109–10 ([C1020]). [C1020] covered an area of approximately 2.5 × 1 m. The colour and texture of it appeared similar to [C1017]. Like the latter, [C1020] may be associated with a patch of dark red peat-ash encountered in grid square L 111. The latter seems to correspond to a positive anomaly encountered during the geomagnetic survey (see Fig. 73). 6.2 Trench 2 The top layer [C2000] was manually removed along with grass and moss, which partly covered the causeway stones (Fig. 76, top). The peat cover was approximately 20 cm thick and directly overlay the natural gravel deposits of the former lake bottom [C2007] on both sides of the causeway. Between the flanks of the causeway, the top soil was approximately 5 cm thick and directly overlay the gravel fill of the causeway. Several post-medieval pottery fragments (SF107, SF108) and one fragment of painted glass (SF106) were recovered from [C2000]. The fill of the causeway consisted of two layers of road metal. The upper layer, [C2001], which formed the walking surface of the causeway, consisted of sharpedged cobbles of up to 20 cm diameter (Fig. 76, centre; Fig. 77). It overlay a layer of somewhat coarser stones, which provided the base of the latter [[C2002]](Fig. 76, bottom; Fig. 78). Apart from the slightly different size of the stones, [C2001] and [C2002] were very similar. This implies that [C2001] and [C2002] were deposited during the same building phase. On the western side of the causeway, the material of [C2001] and [C2002] had partly tumbled through a gap in the stone alignment (Fig. 79). This gap suggests that one of the boulders of the western causeway flank had been removed or fallen out. The missing stone was not found during the excavation. It could be hidden under the peat outside the trench, but it may also have been intentionally removed for some reason. It must be noted that the footing stones at the base of the causeway ([C2006], see below) were also missing in this place. The interface of the missing stone and the subsequent tumbling of [C2001] and [C2002] was included in the matrix as [C2009].

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Fig. 76. Orthophotos (left) and topography (right, 2-cm-contour lines) of [C2000]–[C2002] with the location of special finds.on the last day of the excavation.

Fig. 77. [C2001]: causeway fill after removal of top soil. 53

Fig. 79. [C2009]: road metal fill protruding through a gap in the western flank of the causeway.

Fig. 78. [C2002]: coarse road metal fill of the causeway

Fig. 81. The excavated causeway seen from the east, showing the footing stones [C2005] at the base.

Fig. 80. Trench 2 after the removal of the road metal fill [C2001]–[C2002].

[C2001] and [C2002] contained only post-medieval finds, including glazed redware (SF121, SF172), stoneware (SF123), roof-slate (SF118) and glass fragments (SF119, SF122). A plain whiteware sherd (SF283) was found under the stones of [C2002]. This implies that the road metal fill of the causeway was deposited or renewed in the 19th or early 20th century (see Chapter 8.2.2 and 11.2). [C2002] came off to the natural gravel and stratigraphically overlay the top stones of the causeway (Fig. 80). The flanks of the causeway comprised two construction layers on each side. The upper alignment of boulders, termed [C2003] (west flank) and [C2004] (east flank), was set on a base layer of smaller footing stones, [C2006] and [C2005] respectively (Fig. 81). The latter directly overlay the natural gravel layer [C2007] and formed the (stratigraphically) oldest part of the causeway. Since the excavation of these contexts required the dismantling of a part of the causeway,

Fig. 82. [C2005]: footing stones of the eastern causeway flank after the removal of one of the boulders.

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Fig. 83. Plan of the causeway showing the outline of visible stones and the extent of trench 2.

only one boulder from the eastern causeway flank and the underlying footing stones were lifted (Fig. 82). Surprisingly, a number of bones and post-medieval pottery fragments were found between the footing stones of [C2005]. We cannot think of any natural or even anthropogenic processes that might have slipped these finds under the stones after the causeway was built. Hence, the only possible conclusion is that the

excavated part of the causeway was (re-)constructed in the early modern period. In addition to the excavation of trench 2, the visible parts of the causeway were cleaned and photographed from the air using the camera crane. The orthorectified and georeferenced photos were used to create a detailed plan of the causeway (Fig. 83).

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7

Archaeomagnetic dating By Zoe Outram, Samuel E. Harris and Cathy M. Batt

Archaeomagnetic dating is based on two principles: that the Earth has a magnetic field that changes over time, and that certain events cause magnetic materials to record information about the Earth’s field at that moment in time. In the UK, the record of how the orientation of the Earth’s magnetic field has changed over time, referred to as a secular variation curve (SVC), extends back to 2000BC and is based on observations of the Earth’s field and direct measurements from archaeological materials (Zananiri et al. 2007). The magnetic field is described using three measurable parameters: the declination and inclination provide information about the direction of the field, while the intensity provides information about the strength of the field. Due to the nature of the secular variation of the geomagnetic field, there are a number of occasions in the last 4000 years where the field has been aligned in the same direction, resulting in multiple age ranges (Batt 1998). There are primarily two events that may result in archaeological materials recording information about the past magnetic field: heating materials over ca. 400° C and deposition in water. The features investigated at Law Ting Holm were areas of fired clay and therefore related to heating events. Heating materials within a magnetic field causes the magnetic particles present to align themselves with the applied field (the Earth’s magnetic field). This may result in a thermoremanent magnetisation being recorded by the samples, which can be measured in the laboratory to determine the direction of the magnetic field, before being compared to the secular variation curve in order to provide a date for the last time the feature was heated (Clark et al. 1988). The technique of archaeomagnetic dating therefore allows a date to be produced for the last time fired clay features, such as hearths and kilns were used (Clark et al. 1988). This date usually relates to an anthropogenic activity or process, resulting in chronologically significant information for the interpretation of the use and development of an archaeological site. The technique is sensitive to physical and/or chemical disturbances that can occur during the use, abandonment and decay of the feature, which needs to be addressed during the sampling procedures and laboratory measurements. Oriented archaeomagnetic samples were taken from two areas of burning (Fig. 84) identified during the excavation of the site of Law Ting Holm. The objectives of this work were (a) to determine whether the material had been heated in situ to a high enough temperature to record the geomagnetic field; (b) to provide a date of last use of the feature. All of the laboratory work was carried out in the Division of Archaeological, Geographical and Environmental Sciences, University of Bradford.

Fig. 84. Location of the two areas of burning sampled from the site of Law Ting Holm, Shetland. 7.1 Archaeological Context During the excavations two fired features were sampled for archaeomagnetic dating: context [C1011] was an area of fired clay in the south-west area of the site (Lab. Ref. AM193), while context [C1012] (feature 3) was a large area of in situ burning (Lab. Ref. AM202) which was contained within a rough kerb of stones. Archaeomagnetic dating was selected to date these features due to the clear relationship between the archaeological event of interest and the dated event. Feature AM193 sampled an area of burning composed of fired red-orange silty clay and ash located to the south-west of the site (Fig. 85). The sampled material was approximately 40 % clay, moist and varied between 1 and 4 cm in thickness. The thickness of the material could be used to suggest that the feature was either exposed to high temperatures, or that it was in use for prolonged periods of time. Feature AM202 (T15–T43) sampled a large area of burning approximately 1.7 by 1.5 m in size, which was composed of dark orange to brown silty clay. The sampled material was approximately 40 % clay, which was moist and varied between 1 to 5 cm in thickness. This feature appeared to represent a formal area of burning 57

the feature had been heated sufficiently in the past to record the geomagnetic field, and contained appropriate concentrations of magnetic minerals. However, the variation in the intensity values could be used to suggest that the feature may have been exposed to inhomogeneous levels of heating in antiquity or that the magnetic minerals present were not uniformly distributed throughout the sampled material. The initial magnetic directions were scattered and included some outlying values (e.g. T3, T4 and T8), indicating that the NRM values may not have related to a single magnetic field. The initial NRM measurement was associated with a large 95 value of 31.4, which is outside the practical limit of 5 appropriate for dating (Tarling and Dobson 1995). It was not clear why the feature should return such scattered results but it was suggested that the feature may not represent an in situ deposit, but rather a dump of ash and therefore not in situ from the time of burning. Three samples were selected as pilot samples to undergo step-wise demagnetisation in order to investigate the underlying magnetic properties: T3, T4 and T8. Samples T3 and T4 were selected to represent the anomalous results from the initial assessment and therefore provide information about the possible cause for the outliers. The pilot analysis of the samples indicated that the sampled material was largely dominated by harder magnetic minerals, such as the titano-haematite family of minerals, and that the magnetisation was composed of two components: the component of archaeological interest and a significant unstable component. The pilot analysis demonstrated that the component of lower stability was removed following exposure to a field of 7.5 mT (Tarling and Symons 1967). It was noted that there was a significant improvement in the grouping of the magnetic vectors following the partial demagnetisation of the remaining samples at 7.5 mT, although a number of distinct outliers were still present. The discordancy tests of McElhinny and McFadden (2000, 92) were used to statistically identify two anomalous samples, which were removed from the analysis as outliers. The removal of these samples was accompanied by a decrease in the size of the 95 value to 3.9, which is within the recommended range for dating purposes (Tarling and Dobson 1995). The small 95 value indicated that the remaining samples all recorded the same heating event and that the magnetic direction was datable.

which was contained within a rough kerb (Fig. 86); the fired clay varied in colour from dark orange to brown, which indicated that it was not exposed to uniform heating across the whole area of the feature. 7.2 Sampling Samples were taken from cleaned horizontal surfaces within the feature using the tube method described by Clark et al. (1988). The samples were distributed as evenly as possible across the sampled areas (see Fig. 84). The total extent of [C1011] was not yet clear as the samples were taken. The sample locations are therefore not evenly distributed across this context. The samples were oriented using a magnetic compass in the field, as there appeared to be no local disturbances to the geomagnetic field caused by the feature itself or any other factors. The directions were corrected for magnetic variation using information from the British Geological Survey IGRF synthesis form. The samples were brought back to the laboratories at the University of Bradford, where they were stored in a cool environment until the time that they are measured. 7.3 Measurements The direction of natural remanent magnetisation (NRM) of the samples was measured using a Molspin fluxgate spinner magnetometer. The magnetic directions were assessed using standard statistical tests (Fisher 1953; McElhinny and McFadden 2000, 92), returning a mean value for the direction plus an associated error, the alpha-95 (α95). The alpha-95 represents a 95 % probability that the true direction lies within a cone of confidence around the observed mean direction, and would be expected to be less than 5 for dating purposes. A value larger than 5 indicates that the magnetic directions of the samples are scattered and may therefore not all record the same magnetic field (Clark et al. 1988). The stability of the magnetisation was investigated by the stepwise demagnetisation of selected pilot samples from each feature in fields ranging from 0 to 100 mT (peak applied field), with the remanence being measured after each step. The selection of pilot samples was based on the initial NRM values, investigating a subset of the samples that represented the modal/mean values and those recording anomalous or outlying values. The assessment of the behavior of the pilot samples allowed an appropriate demagnetisation field to be chosen and applied to the remaining samples that removed the less stable components (Tarling and Symons 1967), leaving the magnetisation of archaeological interest, referred to as the characteristic remanent magnetisation (ChRM). After partial demagnetisation in this field the sample remanences were remeasured.

7.5 NRM Results: AM202 (T15–43) A total of 30 samples were analysed from AM202. The variation in colour of the feature noted in the field appeared to be reflected in the intensity values, which ranged from 12.9 to 142.9 ×10-5 Am2. The variation in intensity values could indicate that either the material was not uniformly heated across the entire area of the feature, or that the magnetic minerals present were not evenly distributed throughout the sampled material.

7.4 NRM Results: AM193 (T1–T14) A total of 14 samples were analysed from AM193. All of the samples recorded high values of initial intensity (between 21.5 and 106.5 ×10-6 Am2), suggesting that

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Fig. 85. Detail of Feature AM193 sampled at Law Ting Holm, context [C1011], highlighting the location of the samples (photo: Friel 2011).

Fig. 86. Detail of Feature AM202 sampled at Law Ting Holm, context [C1012] (photo: Friel 2011)

Fig. 87. Summary of the calibration data for AM193 using the CALS3K.3 calibration dataset (Korte et al. 2009) and the Matlab programme developed by Pavón-Carrasco et al. (2011). Top row: master secular variation curves for the observation site (red bold curves with red error bands) of the declination (left), inclination (right) and the undated archaeomagnetic direction (blue line). Middle row: the individual probability density functions for the declination (left), inclination (right). The green lines indicate the 95 % probability threshold. Bottom row: regional map (left) of the data location (red point) and the master secular variation curve location (blue square); combined probability density marked with the green line of probability (centre); and archaeomagnetic dating information (right).

Fig. 88. Summary of the calibration data for AM202 using the CALS3K.3 calibration dataset (Korte et al. 2009) and the Matlab programme developed by Pavón-Carrasco et al. (2011). Top row: master secular variation curves for the observation site (red bold curves with red error bands) of the declination (left), inclination (right) and the undated archaeomagnetic direction (blue line). Middle row: the individual probability density functions for the declination (left), inclination (right). The green lines indicate the 95 % probability threshold. Bottom row: regional map (left) of the data location (red point) and the master secular variation curve location (blue square); combined probability density marked with the green line of probability (centre); and archaeomagnetic dating information (right). 59

Feature AM193

AM202

Dec -10.7 (-10.6)

NRM Inc 31.9 (19.0)

α95 31.4 (n=14)

Dec 1.3 (1.0)

ChRM Inc α95 68.4 3.9 (62.5) (n=12)

11.8 (10.4)

61.6 (54.6)

6.8 (n=26)

10.8 (9.2)

68.1 (62.3)

3.7 (n=26)

Date range at 95 % confidence levels Zananiri et al. CALS3K.3 AD45–540; 230–150BC; AD1190–1600 115BC–AD20; AD90–390; AD850–1610 AD70–630; 860–790BC; AD1040–1345; 220–160BC; AD1360–1630 110–50BC; AD140–145; AD230–380; AD800–1330; AD1430–1600

Table 3. Summary of mean results in degrees and calibrated dates using the UK calibration curve (Zananiri et al. 2007), and the global secular variation dataset CALS3K.3 (Korte et al. 2009): directions have been corrected for magnetic variation, and the directions recorded in brackets have been corrected to Meriden. All dates are cited at 95 % confidence levels.

The assessment of the NRM demonstrated that the samples were relatively well grouped, recording an alpha-95 value 6.8° that only just lay outside of the limit of 5° used in dating. However, a number of outliers were identified at this stage, which included samples that returned negative inclination values (indicative of something inherently anomalous about the samples), as well as low inclination values that may suggest that areas of the feature had been disturbed or compressed in some way in antiquity. Four samples were selected as pilot samples to undergo step-wise demagnetisation in order to investigate the underlying magnetic properties: samples T27 and T31 were selected to represent the outlier samples, while samples T19 and T28 represented the central group of samples. The results of the step-wise demagnetisation demonstrated that there was a clear difference between the magnetism recorded by the outlier samples and those that represented the “central” samples. The outlier samples were clearly dominated by harder magnetic minerals, such as the titano-haematite family of minerals. In contrast, the central samples were dominated by softer magnetic minerals, such as the titano-magnetite family of minerals. The assessment of the samples indicated that they were all composed of two magnetic components, and that the unstable component was removed following exposure to a field of 7.5mT in the outlier samples, and 5mT in the central samples. The variation recorded in the pilot samples did not allow a standard field to be selected to remove the unstable magnetic signal. Therefore, each individual sample was investigated using the step-wise demagnetisation method from 0–10 mT to allow the optimum field to be selected for each sample.

It can therefore be concluded following the step-wise demagnetisation of the samples that the magnetic mineralogy did vary across the feature, with some areas containing harder magnetic minerals. This suggests that either the composition of the sampled material was inhomogeneous, or that the feature was not uniformly heated in antiquity. The removal of the unstable component was associated with a significant improvement in the grouping of the samples, returning an alpha-95 value of 3.7°. It should be noted that the samples that returned negative inclination values following the initial measurements were not improved following the removal of the unstable component and so were not included in the assessment of the mean values. The samples were then assessed to determine if they all recorded the same heating event using the statistical procedures defined by McFadden and McElhinny (2000, 92): two samples (T17 and T34) were identified as possible outlier samples. The removal of the anomalous results from the analysis reduced the alpha-95 value further to 3.4°, suggesting that the samples all recorded the same heating event and that the magnetic direction is datable. 7.6 Archaeomagnetic dating The mean magnetic directions for the NRM and ChRM determinations for the two features have been summarised in table 3, showing the magnetic directions at the site, and after they were corrected to Meriden, the reference locality for the British calibration. The magnetic vectors were relocated to Meriden using the standard method proposed by Noel and Batt (1990). The corrected mean site directions were then dated by comparison with the current UK secular variation curve (Fig. 87–88) developed by Zananiri et al. (2007)

60

Fig. 89. Probability density for the calibrated age range for feature AM193, produced using the UK calibration data (Zananiri et al. 2007) and the RenDate programme (Lanos et al. 2005). Top graph shows the points in time where the geomagnetic field showed the same inclination as sample AM193, middle graph shows the points in time where the geomagnetic field showed declination angle as sampled AM193. The bottom graph shows the combined probability density where the geomagnetic field displayed the same declination and inclination as that recorded by the sample AM193. The grey area represents the date range this occurred at 95 % confidence interval.

Fig. 90. Probability density for the calibrated age range for feature AM202, produced using the UK calibration data (Zananiri et al. 2007) and the RenDate programme (Lanos et al. 2005). Top graph shows the points in time where the geomagnetic field showed the same inclination as sample AM202, middle graph shows the points in time where the geomagnetic field showed declination angle as sampled AM202. The bottom graph shows the combined probability density where the geomagnetic field displayed the same declination and inclination as that recorded by the sample AM193. The grey area represents the date range this occurred at 95 % confidence interval.

using the RenDate calibration program (Lanos 2005). In addition, the magnetic directions (not corrected to Meriden) were also compared to the global data reference data (Fig. 89–90), CALS3K.3 (Korte et al. 2009), calibrated using the MatLab programme developed by Pavón-Carassco et al. (2011). The secular variation curves differ in terms of the datasets that have been used to construct them, and results in subtly different calibrated age ranges being produced for the magnetic directions. The resulting calibrated dates have been summarised in table 3 for the different curves used, and are cited at 95 % confidence levels. The CALS3K.3 dataset has not been widely applied to archaeomagnetic dating in the UK, but can offer a number of advantages. For example, in order to use the conventional regional secular variation curves, the magnetic directions need to be relocated to a central location, which for Britain is Meriden (52.43° N, 1.62° W). It is generally accepted that each secular variation curve is useful for approximately a 500km radius from a central location (Noel and Batt 1990); the site of Tingwall is approximately 800 km from Meriden and so it is possible that errors

were introduced following the relocation of the magnetic directions to Meriden. However, it is important to note that significant differences have not been identified when archaeomagnetic dates produced for other sites in Shetland were directly compared to radiocarbon dates produced on contemporary material (Outram and Batt 2010; Outram 2006). The use of the European field models avoids the errors associated with relocating the site directions to Meriden, as only the relevant information from the specific geographical location is compiled for calibration purposes. However, it is important to note that the maximum latitude value permitted when using the MatLab calibration tool is 60°; the latitude of the Tingwall site is 60.173°. It is not clear how much this will impact on the resulting calibrated date. In addition, it has been noted that characteristic local variations in the geomagnetic field can be smoothed out by data from other areas, thereby decreasing the resolution available in the calibration procedure. Despite these problems, it is interesting to compare the calibrated age ranges produced using the different datasets of archaeomagnetic measurements. The calibration of the archaeomagnetic directional data returned multiple possible age ranges for both of the

61

sampled features. AM193 returned multiple age ranges that focused on either the Middle to Late Iron Age or the Norse to medieval period. AM202 also returned multiple age ranges, placing the feature to within the Iron Age or the Norse–medieval periods. Where multiple age ranges have been produced for a calibrated archaeomagnetic direction, additional information is required to differentiate between the different ranges. This can relate to alternative scientific dating evidence, documentary evidence or artefactual evidence. At the time that this report was written, no radiocarbon dates had been produced and so the artefact evidence was used to aid the interpretation of the dates. Unfortunately, it was concluded that the pottery recovered from the site represented a mixed assemblage of Middle and Late Iron Age pottery (Brown 2012). The mixed nature of the material makes it difficult to use this information to discount the Late Norse–medieval period age ranges in favour of the Iron Age ranges. Additional dating evidence is therefore required to distinguish between the calibrated age ranges produced by the assessment of the fired features.

whether this could be correlated with the activity noted in the documentary sources. The initial assessment of the samples from the two features demonstrated that they both contained measurable remanence, indicating that the material sampled contained sufficient magnetic minerals to record a stable magnetic direction and that they were fired in situ. The assessment of features AM193 and AM202 demonstrated that they recorded well grouped directional data, resulting in the production of an archaeomagnetic dates for the last heating of this feature. Further scientific dating evidence is required to corroborate the archaeomagnetic date produced for the site and distinguish between the Iron Age and Norse–medieval period ranges that were produced. It is suggested that at present, the calibrated age ranges produced following the use of the British dataset should be used for dating purposes until the European datasets can be increased. Calibrated age ranges of AD45–540 and AD1190–1600 (AM193), and AD70–630, AD1040– 1345 and AD1360–1630 (AM202) were produced using the British dataset. It is important to note that all of the calibrated age ranges are possible, and additional archaeological or chronological evidence is required to select the more archaeologically significant range. Summary magnetic measurements are presented in chapter 7.8 and detailed magnetic measurements are available in electronic form on request.

7.7 Summary Two fired features were investigated as part of the excavations carried out at Law Ting Holm. The areas of burning were sampled for archaeomagnetic dating in order to determine when the site was in use, and

7.8 Appendix: The magnetic data Feature AM193 Sample no.

T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14

D degs. 340.6 0.9 0.6 321.4 326.5 316.2 47.1 335.3 316.5 52.5 0.4 43.6 322.1 310.7

NRM I degs. 46.2 26.4 -66.7 71.7 12.7 -26.3 53.7 63.3 81.5 -33.0 24.8 -22.2 57.8 46.0

Field Int arb 69.9 41.2 50.5 97.2 52 38 29.7 59.9 106.5 65.6 21.5 62.7 59.8 54.6

mT 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 62

After partial demag D I Int degs. degs. arb 359.1 66.2 100.80 16.0 70.0 73.20 4.7 35.7 18.50 311.5 83.8 88.40 357.8 59.8 72.10 353.7 60.5 65.60 26.6 72.4 63.10 3.9 69.5 62.70 355.7 73.4 113.28 27.0 67.3 79.93 15.8 70.6 51.90 19.6 63.3 56.90 338.7 68.6 85.90 346.4 71.3 64.30

Pilot? Y/N

Y Y

Y

Feature AM202 Sample no.

T15 T16 T17 T18 T19 T20 T21 T22 T23 T24 T25 T26 T27 T28 T29 T30 T31 T32 T33 T34 T35 T36 T37 T38 T39 T40 T41 T42 T43 T44

D degs. 12.4 17.4 35.8 17.9 358 11.8 354.2 22 307 9 27.5 215 6.9 36.7 352.7 1.9 34.5 342.2 22.8 59.9 1 2.5 21.1 23.9 347.3 22.8 325.5 28.5 2.7 15.7

NRM I degs. 60.2 63.3 37.9 71.3 70.2 60.9 59.7 73.6 -67.3 66.7 70.3 -83.2 26.4 70.7 75.3 47.8 21.2 72.9 77.7 41.1 -26.2 53.5 26.5 72.5 70.7 73.3 70.3 -27.7 56.1 68.9

Field Int arb 75.8903 106.8948 89.616 112.1366 134.6381 108.2449 81.4725 87.6143 19.3301 120.4498 79.5459 43.4578 46.1602 137.8742 52.1023 24.7725 25.4355 44.6081 72.2229 30.2617 25.5787 44.8282 12.9583 29.0293 48.1372 18.4647 110.4882 52.4162 109.5441 142.8651

mT 7.5 5 5 5 5 5 5 5

After partial demag D I Int degs. degs. arb 8.6 65.9 64.2169 3.2 59.5 66.8532 31.8 48.8 75.3562 348.3 78.6 75.1305 11.2 68 85.4029 9.6 61.3 73.7691 359.8 64.7 60.7598 358.4 68.6 60.0153

5 5

14.5 37.1

64.7 74.9

83.8719 58.7153

7.5 5 5 5 7.5 5 5 5

24.9 31.8 359.9 356.7 353.8 358 48.4 52.4

65.3 67.4 76 66.3 61.2 73.7 76.2 58.9

47.4865 104.1583 37.7425 22.2208 24.0564 39.523 66.4334 33.6291

5 5 5 5 5 5

14.5 24.2 20.1 8.9 32 340.1

73.8 53.5 67 77 82.3 64.7

38.9141 24.3701 24.4101 36.2549 17.0778 99.8362

5 5

17.6 14.6

56.2 73.1

99.983 122.2858

63

Pilot? Y/N

Y

Y Y

Y

8

The artefacts 8.1 The prehistoric pottery By Louise D. Brown The assemblage of coarse pottery from the 2011 excavations at the Law Ting Holm, Tingwall comprises over 1,300 sherds which were all found in trench 1 (Table 5). Trench 2 yielded only post-medieval pottery fragments (see chapter 8.2). The assemblage has been characterized principally in terms of vessel form, and secondly in terms of fabric. The fabric, clay and inclusions, was recorded macroscopically using a hand lens (×8 magnification); no thin section work was carried out to investigate the source of the clay and inclusions (as described by MacSween (2009, 37).

During the excavation at Law Ting Holm a total of 7,028 artefacts were found, 6,942 in trench 1 and 86 in trench 2 (Table 4). Both artefact assemblages are quite different. The majority of finds from trench 1 consists of bone fragments, followed by pottery sherds and stone artefacts. With the exception of a few post-medieval artefacts found in the top layer, all finds from trench 1 are of prehistoric date. The artefacts were sent to specialists in Bradford, Edinburgh and Vienna for further analysis. The finds recovered from trench 2, on the other hand, are all of post-medieval date. Flotation samples were collected from every grid cell within each context for analysis in Shetland. However, due to a lack of funding, neither the archaeobotanical remains nor the burnt organic matter discussed in chapter 6.1 could be analysed. Upon completion of this report they, as well as all artefacts and bones, were handed over to the Shetland Museum in Lerwick.

8.1.1 The assemblage In general, the assemblage is moderately to heavily abraded, surviving as medium-sized and small sherds. Whilst some larger sherds are present within the

Trench 1

C1000 C1001 C1002 C1003 C1004 C1005 C1006 C1007 C1008 C1010 C1011 C1012 Profiles Spoil heap Sum

Bone 98 61 19 1,638 1,560 69 42 5 1,354 6 7

Pottery 61 37 45 4 668 407 7 5

Metal 1 1 2 2

222

Slag 8 8 1

Stone 7 4

Organic

Other 3 1

141 25 25

40 17 5 1

73 49 5

2 61

24

48

2

1 23 3

41

2

4,859

1,497

8

271

1 99

175

33

Bone

Pottery 5 20 38 4 67

Metal

Slag

Stone

Organic

2

Other 1 6

2

7

Sum 178 111 66 5 2,585 2,063 111 48 7 1,711 6 7 43 1 6,942

Trench 2

C2000 C2001 C2002 C2005 Sum

7 3 10

Table 4. Sum of artefacts from trench 1 and trench 2. 65

Sum 6 28 45 7 86

Context u/s 1000 1001 1002 1004 1005 1006 1007 1010 Total

Rim 0 1 0 2 27 15 0 0 10 55

Base 0 6 0 6 21 17 0 0 8 58

Body 0 22 2 7 89 55 1 1 23 200

Fragment 4 22 9 47 501 303 5 4 161 1,056

Reworked 0 0 0 0 6 6 0 0 2 14

Total 4 51 11 62 644 396 6 5 204 1,383

Table 5. Number of sherd types from each context.

assemblage, for the most part it survives in a highly fragmentary state. The majority of the assemblage (over 90 %) comprises non-diagnostic body sherds and fragments. The rim and base sherds each represent 4 % of the total assemblage (58 base sherds and fragments, 55 rim sherds and fragments) and three decorated examples (one rim, one body, one fragment) were noted. In addition, 14 reworked pottery sherds (making up six small find numbers), representing 1 % of the total assemblage. These sherds are discussed in more detail below. Mixtures of inclusions were recorded within the assemblage reflecting: the natural mineral content of the clay (for example mica “dust”), the mineral components readily available for use as a temper, and the need to change and adapt to the clay being worked (in terms of plasticity, water content, etc). It is difficult to determine if the inclusions noted have been added intentionally or accidently added (Rye 1981, 31–32). The inclusions seen in this assemblage, dominated by both steatite and quartz, are seen (in broad terms) in other Shetland assemblages and are chronologically significant (see, for example, Brown 2010; Brown forthcoming). In general, it is seen that the sherds with a high steatite component to the clay are more heavily abraded and tend to be thicker-walled sherds. Here, the material is often seen as having lost one or both surfaces. This material is regarded as Middle Iron Age. The remainder of the sherds tend to be thinner-walled and of a sandy clay with small quartz grit and occasional mica inclusions. A correlation is seen in the fineness of a vessel’s wall thickness and in the fineness of the fabric (allowing more plasticity required for making finer wares). This material is viewed as being typically Late Iron Age/Pictish. A variety of rim sherds are present within the assemblage (Fig. 91). No single type dominates the assemblage (not including the fragments which were

considered too small and/or abraded to identify). The ‘straight’ type were often small-sized sherds which may represent rims from thin-walled, inverted (or “bucket”-shaped vessels – see Hamilton 1956, 82, Fig. 41). This inverted form (for example SF223 – Fig. 92, and FN240 – Fig. 93) relates to the Late Iron Age or Pictish period (Brown 2010). A single inverted rim sherd, FN256 (Fig. 94), has an incised line running around the circumference of the vessel, approximately 4 mm from the abraded rim top. Examples of beaded rims were found to be both thinwalled and of a sandy clay with quartz inclusions (for example FN113 and FN222 – Fig. 95), but more often a medium-walled sherd with a high steatite component to the clay (for example SF349 – Fig. 96). In these instances the exterior surface had been burnished. A similar split was seen in the everted rim sherds, those that were more pronounced were of a sandy clay, whereas moderately everted rims (perhaps simply a sharp out-turning of the rim) were recorded as thicker-walled and of a fabric high in steatite inclusions (for example FN232 – Fig. 97).

Fig. 91. Rim types present as a percentage of the total number of rim sherds.

66

Fig. 92. Thin-walled, inverted rim sherd, SF223.

Fig. 93. Thin-walled, inverted rim sherd, FN240.

Fig. 95. Conjoining beaded rim sherds, FN113 and FN222.

Fig. 94. Thin-walled, inverted rim sherd with incised linear decoration, FN256.

Fig. 97. Everted rim sherd, FN232.

Fig. 96. Beaded rim sherd, SF349.

67

Fig. 98. Base types present as a percentage of the total number of base sherds. There is little variation in the base types present within the assemblage (excluding the flat, bottom part of the base and the fragments); the splayed type present in marginally fewer numbers than the round- and square-angled type (Fig. 98). Two decorated fragments (in addition to the rim sherd detailed above) were recorded from within the assemblage. There are a small number sherds with incised markings on the surface of sherds which have not been reported on here as they represent accidental marking rather than deliberate decoration or marking. The first decorated example, FN336 (Fig. 99), is a small fragment that has two concentric bands impressed on its surface, each ca. 6 mm wide and ca. 6 mm apart. The dark grey fabric contains small amounts of both steatite and quartz grits. A more intricate decoration is seen on SF245 (Fig. 100). The incised, banded decoration comprises an incised chevron motif set within concentric lines. The sherd is a thin-walled, and made of a sandy, orange clay. This type of design is broadly similar to an example from the Later Iron Age deposits at Scalloway (MacSween 1998, 135, Fig. 83 – No. 5).

Find No.

Context

Grid

Inclusions

197

1004

H104

Steatite

FN220 226 252 306 FN323 336

1004 1004 1004 1005 1005 1005

L108 K109 H109 I107 K106 K108

Steatite Steatite Quartz Quartz Quartz Steatite

353

1005

K110

Steatite

421 455

1010 1010

G102 K104

Steatite Steatite

Fig. 99. Decorated fragment, FN336.

Fig. 100. Decorated body sherd, SF245.

Description Two conjoining fragments. One section smoothed. Burnisher Rim, reshaped post-firing One edge smoothed. Burnisher Two perforated body sherds Perforated fragment Perforated fragment Spindle whorl fragment? Three conjoining fragments forming a crude, abraded spindle whorl Three sections smoothed. Burnisher Perforated fragment

Table 6. Reworked pottery sherds.

68

8.1.2 Reworked sherds 14 sherds from the assemblage (represented by ten small find numbers) have been reworked (Table 6). The majority of these sherds have a high steatite content within the clay matrix; the high steatite content making the sherds easy to rework. Those with quartz inclusions are fragments of thin-walled vessels that, along with the example from steatitic clay, have been perforated at some point post-firing of the vessel (for example FN252 – Fig. 101). These perforations are often crudely executed and are located close to a section edge, or are at the site of a section break (for example Brown 2010, 210, Figure 6.2.3, SF8522 and 216, Figure 6.2.7., SF15690). The more extensively worked sherds are all made from steatitic clay sherds. From within this group are three examples of burnishers (for example FN421 – Fig. 102). These sherds are all reworked from sherds with a high steatite component and have one or more smoothed, flat edge/s. In addition to the crudely perforated sherds, two examples (FN336 – Fig. 103; FN353 – Fig. 104) appear to be heavily abraded spindle whorls; the straight perforations are well executed and larger than the other perforations seen in the assemblage.

A final type of reworked sherd is SF220 (Fig. 105), a reworked rim. The sherd has a groove cut into the external surface of the sherd below the rim. This groove has been cut into the sherd at some point during the vessel’s life. The top of the rim also looks reworked and it is possible that the whole of the rim has been reworked.

Fig. 103. Spindle whorl fragment, FN336.

Fig. 104. Spindle whorl fragment, FN353. Fig. 101. Perforated body sherd, FN252.

Fig. 105. Reworked rim, SF220.

Fig. 102. Reworked sherd, FN421. 69

8.2 The post-medieval artefacts By Natascha Mehler

A similar group of reworked sherds was identified from the Middle Iron Age phases at Old Scatness, Shetland (Brown forthcoming). Here, sherds with a high steatite content had been selected and reworked into a variety of objects including sherds identified as burnishers, or pottery smoothers, and several examples of complete and broken spindle whorls. The excavations at Kebister also identified an assemblage of reworked pottery fragments, the majority of which were recovered from redeposited and cultivation deposits (Dalland and MacSween 1999, 200)

8.2.1 Trench 1 Trench 1 on Law Ting Holm yielded 23 post-medieval artefacts (Table 7). The majority stemmed from the top soil [C1000]. [C1001], which probably represented the interface between the top soil [C1000] and layer [C1002] below, yielded a modern glass bottle fragment and [C1003] contained four fragments of redware ceramics. [C1003] was interpreted as a modern truncation. All datable artefacts were produced between ca. 1700 and 1840. They include a decorated Dutch clay pipe stem (SF008), a fragment of slipware (Fig. 106) and several creamware sherds (FN049, FN055, FN059). SF043 is a fragment of hand painted blue and white pearlware (Fig. 107) that dates to about 1775–1840 (Miller 1991). No later artefacts were found.

8.1.3 Summary The assemblage of coarse pottery is a mixture of Late and Middle Iron Age pottery. The contexts that yielded the most pottery directly sealed one another, they are: [C1004], a midden layer extending across the whole trench; [C1005], a stonier deposit underlying [C1004] in the eastern and central areas of the trench; [C1010], a less stony layer below [C1005] which covered approximately two-thirds of the trench in the southwestern zones (Coolen and Mehler 2011, 18–21). Each of the contexts contains a mixture of pottery; no differentiation was seen in the contexts which might have suggested chronological deposition. The assemblage suggests that it forms part of a midden deposit that had been redeposited at this location, perhaps as a levelling event or simply a midden spread.

8.2.2 Trench 2 A total of 86 post-medieval artefacts were found in trench 2, which cut through the causeway (Table 8). The relatively large number of post-medieval finds is partly explained by the fragmentation of sherds from the same vessel, e.g., SF121 and SF172. The excavation uncovered the large stones that had been part of the causeway and also revealed a road metal fill (layers [C2001] and [C2002]), which contained mixed finds material dating

Find no.

material

sum

context

grid

001 005 SF008 SF009 SF010

pottery pottery clay pipe pottery pottery

1 1 1 3 2

C1000 C1000 C1000 C1000 C1000

L102? I109 L100 L101 L101

SF043

pottery

1

C1000

I106

049 052 055 SF056 059 064 099 SF111 156

pottery glass pottery pottery pottery glass pottery glass pottery

1 1 3 1 2 1 1 1 3

C1000 C1000 C1000 C1000 C1000 C1000 C1003 C1001 C1003

I107 J103 K107 J108 I104 I108 L100 J105 L100

redware, rim, orange lead glaze (17th/18th century) redware decorated stem fragment, dutch, ca. 1750–1800 redware redware, base fragment pearlware, hand painted blue and white (ca. 1775–1840) creamware (1762–1820) window pane creamware (1762–1820) slipware creamware (1762–1820) bottle fragment redware bottle fragment redware

Table 7. Post-medieval finds from trench 1.

70

Fig. 106. SF056, a fragment of slipware from [C1000].

Find no.

material

sum

context

SF096

pottery

1

C2000

SF106 SF107

glass, painted pottery

1 1

C2000 C2000

SF108

pottery

3

C2000

SF118 SF119 SF120

roof slate glass brick

2 1 4

C2001 C2001 C2001

SF121

pottery

16

C2001

SF122 SF123

pottery, glass pottery

2 1

C2001 C2001

150

pottery

2

C2001

SF172

pottery

35

C2002

SF173

pottery

2

C2002

SF283

pottery

1

C2002

305

pottery

4

C2005

Fig. 107. SF043, a fragment of hand painted blue and white pearlware, from [C1000].

description whiteware, plate, possibly same vessel as SF108 (ca. 1830–20th century) stoneware, same vessel as SF123 whiteware, plate, possibly same vessel as SF096 (ca. 1830–20th century)

slipware, all fragments from one vessel, same vessel as SF172 redware stoneware, same vessel as SF107 1 fragment of white salt glazed stoneware (ca. 1720–1770), 1 fragment of redware slipware, same vessel as SF121 white salt glazed stoneware (ca. 1720–1770), 1 whiteware fragment (ca. 1830–20th century) found at the bottom of C2002, whiteware fragment (ca. 1830–20th century) flower pot fragments

Table 8. Post-medieval finds from trench 2.

71

Fig. 109. SF121 and SF172, fragments of a redware vessel with a thick white slip at the inside, from [C2001] and [C2002].

Fig. 108. SF107 and SF123, two matching sherds of a stoneware vessel from [C2000] and [C2001].

from the 18th, 19th and possibly the 20th centuries: pottery and glass fragments, as well as pieces of brick and roof slate (see Chapter 8.8.2.9). Both contexts revealed pottery fragments that belonged to the same vessel, proving that they were deposited in immediate succession. SF107 and SF123 are two matching sherds of a stoneware vessel, most likely a jug or pitcher (Fig. 108). It resembles English Brown Salt Glazed type stoneware which was produced between ca. 1675 and the 19th century (Hildyard 1985). The sherds were found in [C2000] (SF107) and in [C2001] (SF123). SF121 and SF172 are very fragmented sherds of a redware vessel with a thick white slip on the inside (Fig. 109). Datable fragments from [C2001], the top road metal fill layer, include FN150, the base fragment of a press-moulded white salt glazed stoneware bowl or cup, a ceramic type that was produced between ca. 1720 and 1770 (Fig. 110). The other artefacts found in the same layer can only roughly be dated to the 18th and 19th centuries. The diagnostic artefacts from [C2002] include another fragment of white salt glazed stoneware (SF173, ca. 1720–1770) and one fragment of plain whiteware (SF173). Another plain whiteware sherd (SF283) was found at the bottom of [C2002], just above the natural gravel (Fig. 111). Plain whiteware was produced in England from ca. 1830 onwards into the 20th century (Miller 1991). SF283 therefore provides a clear terminus post quem for the construction of the fill between the two rows of stones that comprise the causeway. [C2002] was deposited after 1830. [C2005] was a layer of small footing stones which formed the base for a large boulder, which was part of the causeway. It contained four fragments of an unglazed

Fig. 110. FN150, fragment of a press molded white salt glazed stoneware from [C2001].

Fig. 111. SF283, plain whiteware fragment from [C2002].

72

fine redware vessel that was most likely a flower pot. Unfortunately, these fragments cannot be dated more precisely, although they do appear to be quite modern. Not all of the post-medieval pottery fragments found in trench 2 could be dated (e.g. the roof slate and brick fragments as well as the fragments of modern bottle glass) but the few that were dated, provided clear dating evidence suggesting that the causeway fill was constructed after 1830. No artefacts dating from earlier than the 17th/18th centuries were found in trench 2. The artefacts were most probably modern settlement debris disposed of in the area. The nearest settlement is that of the Tingwall manse on top of the nearby hill.

concentrated in Scottish archaeological sites (Newton 1999a). The majority of these sites are found in the Western Isles and Orkney and Shetland. As of 2013, some 150 pumice locations have been identified in Scotland, with over 2,500 individual pieces recovered (Newton, in prep). The age of these archaeological sites ranges from the Mesolithic sites of Staosnaig on Colonsay (Newton 2001) and Camas Daraich on Skye (Newton 2004), through the Neolithic, Bronze and Iron Ages to the Norse–medieval finds at The Biggings on Papa Stour, Shetland (Newton 1999b). Newton (1999a) found that Scottish archaeological pumice is most frequently found in Neolithic to Iron Age contexts, with the Iron Age containing the most frequent finds. Shetland follows a similar pattern. Pumice has been found at over 25 archaeological sites in Shetland and nearby sites include Kebister, Clickhimin, Scalloway, Upper Scalloway and Outnabreck (listed in Newton 1999a). The excavations at Law Ting Holm, Tingwall have produced 24 pieces of pumice, all of which were found in trench 1. This report aims to describe the pumice, establish its origin and compares the finds to others from Shetland and elsewhere.

8.3 Pumice By Anthony J. Newton Ocean-transported pumice has been found at sites across the North Atlantic region, from Arctic Canada, Greenland, Iceland, the British Isles, Scandinavia and Svalbard. Detailed summaries of these finds can be found in Binns (1971) and Newton (1999a). The last major study found pumice at over 150 sites in the British Isles, but finds were

Context 1000 1001 1004 1004 1004 1004 1004 1004 1004 1004 1004 1005 1005 1005

Find

Grid square K102

size (cm)

SF41 5.5 × 5.5 × 3.5 116 2 × 2 × 1.5/3 × 1.5 × 1.5 135 G101 4×3×3 160 I102 3.5 ×2.5 × 2 174 I101 4 × 3 × 2 /2 × 1 × 1 179 J102 2.5 × 1.5 × 1 192 J103 5 × 4.5 × 2 240 H107 2×1×1 247 J111 2.5 × 2 × 2.5/3 × 2 × 1 SF253 G107 7×4×2 SF266 H109/110 5 × 5 × 3.5 293 H105 2.5 × 1.5 × 2 300 J107 4.5 × 3 × 2 367 J111 4 × 3 × 2.5

1006

375

G103

2 × 2.5 × 2.5

1006

397

K102

3 × 2 × 1.5

1010

403

G100

3.5 × 3 × 1.5

1010

433

H104

5×3×3

1010 1010 1010

452 468 479

I107 H108 K111

3 × 2 × 1.5 3×3×2 4.5 × 3 × 3

Description of pumice

Number

brown pumice - grooved brown pumice - 2 pieces brown pumice - groove brown pumice - possible groove brown pumice - plus one smaller piece brown pumice brown pumice - flattened/groove brown pumice - angular - looks layered brown pumice - 2 pieces brown pumice - flattened brown pumice - flattened or broken side brown pumice brown pumice - similar to 367* brown pumice - burnt?* brown pumice? - burnt? covered in brown material* brown pumice - flattened or 1/4 of large piece brown pumice? - burnt?* (labelled „Daub fragment“) brown pumice - grooved - needs cleaning brown pumice brown pumice - rounded/broken brown pumice

1 2

Table 9. Description of pumice. 73

11

3

2

5

layers matching the geochemical composition of the pumice, along with pumice, can be found on the slopes of Katla and in the surrounding area (Newton 1999a; Larsen et al. 2001). The pumice found at Law Ting Holm physically matches the Neolithic and younger pumice which is so frequently found in coastal Scottish archaeological sites. The last known dacitic pumice producing eruption of Katla occurred around AD400 (Larsen et al. 2001). The white Papa Stour pumice was produced by an eruption of Öræfajökull in AD1362 (Newton 1999b).

8.3.1 Pumice Description All of the 24 pieces of pumice (Table 9) were examined and were found to be light to dark brown coloured pumice with glassy vesicles (where this could be observed). A single piece of pumice was recovered from [C1000] (top soil), two pieces from [C1001] (the fill of the shallow depression in J–K 103–105), 11 pieces from [C1004] (midden deposit), three from [C1005] (underlying [C1004] and containing dark brown sandy soil and gravel and cobbles), two pieces from [C1006] (L-shaped concentration of boulders) and five from [C1010] (dark brown layer of sandy loam with lower content of stones, below [C1005]). The pumice only underwent a physical examination and no geochemical analyses or subsamples were taken. The pumice is typical of other finds from Shetland (e.g. Newton 1999a; Newton 1999b; Dugmore and Newton 1999), in its prehistoric age and physical appearance. The pumice also has a similar appearance to the majority of the ocean-transported pumice found throughout the North Atlantic region. Some of the pumice shows evidence of having been worked. Pumice finds SFN41, FN135, FN160*, FN192 and FN433 contain one or more grooves, whilst finds FN192, SF253, SF266* and FN433* have flattened faces (* denotes possible evidence of working). The former suggest that the pumice has been used for sanding a rod like object (e.g. wood, bone or antler) and the flattened faces are probably caused by sanding action on larger objects such as wood or even the preparation of animal hides. Most archaeological sites contain pumice which displays evidence of working (Newton 1999a). When originally collected from either a contemporary or raised beach, it is likely the pumice was rounded by typical beach processes – as seen on raised beaches in Iceland and Norway. Although not a vital resource, pumice was used widely throughout coastal areas of Scotland as an abrasive tool to smooth and sharpen wood, bone and antler, create fishing floats, smooth skins and also as jewellery.

8.3.3 Summary The Law Ting Holm pumice adds to the picture of pumice being widely used in Shetland during prehistoric times. Several pieces show evidence of being used as an abrasive tool and the resultant marks resemble worked pumice found elsewhere. The pumice was produced by one or more eruptions form the Katla Volcanic System and the last known activity of this kind was around 1600 years ago. 8.4 Stone artefacts By Joris Coolen The stone assemblage from the Law Ting Holm comprises 71 stone finds with a total weight of 36.7 kg. Apart from two roof tile fragments from trench 2, all stone artefacts were found in trench 1. Some of the finds do not show obvious traces of working or use and are therefore not clearly identifiable as artefacts. For completeness, the more dubious finds are nevertheless included in this report. The vast majority of stone artefacts were retrieved from contexts [C1004], [C1005] and [C1010] (Table 10). There are no obvious differences among the assemblages from these individual contexts, apart from the relative scarcity of cobble tools in [C1005]. Four roof tile fragments clearly fall out of the prehistoric tool assemblage, but these were all retrieved from the upper layers in trenches 1 and 2. 8.4.1 Cobble tools

8.3.2 Origin of the Pumice Recent studies have shown that the ocean-transported Scottish archaeological pumice was all produced by Holocene eruptions in Iceland (Dugmore and Newton 1999; Newton 1999a, 1999b, 2001, 2004, unpublished; Newton and Dugmore 1995 and 2003). All of the pumice, except for the white pumice found at Papa Stour, was produced by eruptions from the Katla Volcanic System. Although this volcano usually erupts basaltic tephra (volcanic ash) and pumice, throughout the Holocene it has also has periodically produced more dacitic tephra and pumice and it is this activity which created the ocean-transported pumice (Newton 1999a; Larsen et al. 2001). The Mesolithic pumice, found at a few sites in the Hebrides, is more silicic than the pumice found in younger contexts, but it was still erupted by Katla. Tephra

8.4.1.1 Grinders/pounders With a total number of 17 finds, grinders and pounders present the largest group within the stone assemblage, along with plain pebbles. Seven finds were identified as grinders. They are round or flat-faced oval cobbles with faceted, ground faces on multiple sides. Their diameters range from 75 to 108 mm, and the complete specimens weigh between 569 and 1,159 g. The reddish colour of one fragment of a large grinder from [C1010] (FN482) suggests that it may have been exposed to fire. Two finds were identified as pounders or hammerstones. These finds have elongated shapes and show traces of pecking and flaking at one end. However, grinders and pounders cannot always be clearly distinguished, as many of the cobble tools show

74

C1000 C1001 C1004

C1005 C1006 C1007 C1010 C2001

spoil heap/ sum stray find

cobble tools grinder/pounder quern quern rubber whetstone/ burnisher unspecified cobble tool flaked/chipped laminated stones rectangle stone disc perforated disc other bead whorl pebble vessel anvil? roof tile undefined sum

1

9 1 1

1

1

1

2

3

4 1 2

1

1

1

2 5

2

1 1

1 2 1 1 5 4

1

9

3 1

2 5

2 1

3 31

17 2 6

13

3

1

2 13

2

2

1 3 2 1 1 17 4 1 4 5 71

Table 10. Stone artefacts and artefact types per context.

traces of both grinding and pecking or flaking. All of the grinders and pounders found are made of finegrained quartzite, granite or quartz sandstone cobbles. SF190 is somewhat different from the other grinders and pounders but is included here. It is an elongated, flattened quartz sandstone cobble with parallel sides that is gently pecked along the edges (Fig. 112, left). The broader, flattened sides are very smooth and may have been used for burnishing. The object was originally classified as a whetstone, but the use wear along the edges indicate that it was used for pounding rather than sharpening or grinding. Similar artefacts have been found in larger quantities in Scalloway and have been termed “Group A” or “side-faceted cobbles” by A. Clarke (1998a, 144; 2006, 48ff.). Based on the gloss residue, which she observed on many of these tools, Clarke suggested that they may have been used to make paste or pulp from plants or animal products.

fragments of (saddle?) querns could be identified. This situation is not uncommon at prehistoric sites on the Northern Isles, leading Clarke (2006, 46) to suggest that the pounder/grinders were used on more portable and less durable surfaces.

8.4.1.2 Querns Considering the larger number of grinders and quern rubbers found during the excavation at the Law Ting Holm, it is somewhat remarkable that only two

Fig. 112. A side faceted cobble (SF190, left) and two possible whetstone fragments (FN202 and SF80).

75

Fig. 113. Fire-cracked and blackened quern fragment (SF381).

A large quern fragment (FN280) was identified among the stones on the spoil heap but was most likely retrieved from [C1004]. This fragment is an approximately rectangular piece of coarse-grained rock containing quartz and feldspar (possibly granite) with side lengths of 14–20 cm. It has one slightly concave, pecked face, but the original shape or size of the quern cannot be determined. SF381 (Fig. 113) is a piece of a quern with steep, right-angled sides and a slightly hollowed, smooth upper face, which was retrieved from [C1006]. The fine-grained granite has become extremely friable due to extreme or repeated heat exposure. Another find that deserves mention here is a (granite?) boulder with one hollowed side (FN471), which lay with the hollowed side down in [C1010] (Fig. 114). Although no obvious traces of working were observed on the boulder, it was noted that the stone may have been part of a large trough or quern. For logistic reasons, the stone was left in the field and could therefore not be further analysed. It is therefore not included in table 1 or the catalogue of stone artefacts.

Fig. 114. Possible trough or quern fragment from [C1010] (FN471). The scale division is 20 cm. modification has also been observed on quern rubbers from other sites and may have been intended to prevent excessive attrition along the edge during grinding (Clarke, pers. comm. 18-9-2013). All of the tentative quern rubber fragments from the Law Ting Holm have a smooth convex side, which most likely represents the original (naturally ground) surface. SF377 shows definite traces of grinding on the flat face. SF257 and FN484 also have rather smooth and flat faces, with traces of possible pecking and grinding. FN402 is ground along the faceted edge, which, depending on the orientation, may also be the original bottom. The remaining two fragments (FN444 and FN390), however, have very coarse faces. 8.4.1.4 Whetstones? Two finds were classified as possible whetstones (Fig. 112, centre and right). Bulk find FN202 contained an elongated, ovoid sandstone cobble with smooth surfaces. One side is slightly hollowed, possibly as a result of grinding. SF080 is a small, pointed end of an ovoid quartzite or quartz sandstone cobble with flattened faces. SF080 has a smooth surface, although one edge is slightly rougher and is (naturally?) flaked at the tapering end. This find shows no distinct traces of use but may well have been used as a whetstone or burnisher.

8.4.1.3 Quern rubbers Six finds were classified as fragments of quern rubbers. All have similar D-shaped sections and are made of similar material; five are made of large, coarse-grained arcosic quartz sandstone, while the sixth piece (FN390) is made of medium-grained quartzite. As none of the tentative quern rubber fragments has a complete section, the original size cannot be reconstructed. The tentative quern rubbers are fragments of round or oval cobbles that have primarily been split in half to create a D-shaped section. Some of the rubbers (most notably SF257 and FN402) are faceted along the edge. This

76

Fig. 115. Rectangle found on the Law Ting Holm during the backfilling of trench 1. 8.4.2 Flaked and chipped laminated stones 8.4.2.2 Stone discs Three small, subcircular stone disks were found during the excavation. Their diameter ranges from 43 to 64 mm. The largest specimen, SF346, was made from a quartz phyllite pebble shaped by chipping (Plate 1.3). SF273 and FN117 were made of reddish-brown quartz sandstone slabs. The edges were chipped, but FN117 may have been additionally ground along parts of the edge (Plate 1.2). Stone discs are a common type of find at prehistoric sites throughout Atlantic Scotland. Larger specimens are usually interpreted as pot lids (Clarke 2006, 37f.), while smaller discs may have been used as gaming counters (cf. Bashford 2010, 234; Clarke 1999, 157). The specimens from Tingwall lie in the smaller range. The majority of the stone discs excavated in Scalloway have diameters between 50 and 90 mm (Clarke 1998b, 144), while the discs found in Kebister range from 39 to 176 mm in diameter (Clarke 1999, 157).

8.4.2.1 Rectangle A worked bar made of phyllite was found at the lakeside during the backfilling of trench 1 (Fig. 115; Plate 1.1). This bar most likely originated from the spoil heap and may not have been recognised as an artefact during the excavation. The rectangular bar is slightly tapered towards the proximal end and has a D-shaped section. The dorsal side is concavely tapered towards the cutting edge, while the proximal end is slanted at an angle of approximately 45°. The ventral side is almost flat, apart from ancient damage at the proximal end. The cutting edge is flaked, but this may represent modern damage. The shale bar shows traces of hafting and wear across the upper half: parts of the surface appear polished, and there is a small, smoothened notch on one side, which may have been caused by a string or the edge of a haft. Rectangles or stone bars11 are common elements in prehistoric stone tool assemblages in Shetland and Orkney. Their precise use has been a topic of discussion, but it is generally believed that they were used as hoes or mattocks (Clarke 2000, 91; 2006, 30).

8.4.2.3 Perforated discs The assemblage consists of two remarkable perforated slabs, the function of which is unclear. SF126 is a subrectangular slab 155–160 mm in diameter, with a carefully drilled, cylindrical hole near the centre (Fig. 116; Plate 1.4). The slab is up to 22 mm thick and has been carefully shaped by flaking and grinding along the edges. The perforation has a diameter of 23 mm. The second fragment is part of the bulk sample FN129 (Plate 1.5). It is broken across the perforation, and if we assume the latter to have been central, the diameter

A. Clarke (2006) has tried to differentiate between “flaked stone bars”, which she counts among the group of “flaked blanks”, and “rectangles”, which she files under “chipped laminated material”. The former are mostly made of sandstone, shale or schist and are shaped by flaking over the entire surface, while the latter are only flaked around the edge. According to this definition, the object from the Law Ting Holm represents the latter type. However, Clarke (2006, 38) admits that “it has been difficult to identify the point at which the flaked stone bars can be separated from the rectangles, if indeed there is such a division”. 11

77

Fig. 116. Perforated stone disc (SF126). of the disc must have been similar to SF126. The perforation has a diameter of 35 mm and has been pecked rather than drilled, resulting in a conical edge. It is interesting to note that both finds were found in adjacent grid squares within the same context, [C1004]. Both are made of the same material, calc-silicate gneiss, with the larger specimen having some limonite components. Perforated stone slabs and cobbles are common elements of prehistoric assemblages in Shetland, but the two objects from Tingwall cannot be easily matched with other finds. The smaller object, FN129, may be a fragment of a “heart-shaped piece” (Clarke 2006, 38ff.), but its original shape seems to have been subrectangular rather than triangular. The larger find, SF126, might be interpreted as a weight, but it differs from other weights found in Iron Age contexts in Shetland. The latter are primarily cobbles or unworked sandstones with an eccentric, biconical perforation created by pecking (e.g., Clarke 1999, 157ff.). The careful shaping of the edges and the drilled perforation of SF126 seem unusual for a weight and puts it in the group of stone discs. It is not clear whether the hole was part of the initial design (e.g., to attach a handle to the pot lid) or reflects a secondary function. A similar but slightly smaller perforated stone disc was found in a Pictish/Viking Age layer in Old Scatness (Bashford 2010, 233). Based on a number of concentric grooves, this find has been interpreted as a rotating base plate for pottery production, but the perforation, which is slightly off-centre, seems to be a later modification. Furthermore, two of the stone discs found in Scalloway have a central, pecked perforation (Clarke 1998b, 145).

8.4.2.4 Bead [C1004] contained a complete bead of red sandstone (SF258; Plate 2.3). This specimen has a diameter of 22 mm, and the diameter of the perforation is 9 mm. 8.4.2.5 Whorl [C1004] also contained a steatite whorl with a biconical section (SF181; Plate 2.2) or profile C, after Walton Rogers (1997). This specimen is made of a reddish, coarse-grained type of steatite and has a diameter of 46 mm. The perforation is slightly off-centre and has a diameter of 16 mm. Similar whorls have been recovered, for example, at Old Scatness (group 3; Forster 2010, 264; Forster forthcoming), although the Tingwall example appears to be quite large in comparison. 8.4.2.6 Vessels The assemblage comprises at least three fragments of stone vessels, all of which were retrieved from [C1004]. All three clearly identifiable vessel fragments are parts of round vessels. However, the original sizes or shapes of the vessels cannot be reconstructed with certainty. The wall thicknesses range from 9 to 23 mm. The materials of these fragments are highly diverse, indicating various sources. Two fragments (FN235, SF269; Plate 2.4-5) are made of steatite, while the third (FN145; Plate 2.6) was identified as phyllite or schist. One body fragment (FN235) has burnished surfaces and burnt accretions on both sides. Another worked fragment from [C1004] (FN270; Plate 2.7) is included here, although its interpretation as a vessel fragment is doubtful. The fragment is nearly cylindrical and is only 6–7 mm thick. The surface is rather coarse on the outside, while the inner (concave) side is smooth and shows diagonal tooling marks. The

78

white or greyish in colour. Most of the pebbles consist of quartzite, but some are pieces of (aplitic) granite, granite gneiss and granodiorite gneiss. Apart from the possibly painted and fire-cracked pebbles, this group does not show evident traces of anthropogenic modification. It is therefore unclear whether they represent artefacts, but they do appear to be non-local to the area of the Holm and stood out among the otherwise sharp-edged rubble of the respective contexts. Concentrations of small rounded pebbles have also be found at other prehistoric sites in Shetland and have been interpreted as sling stones or gaming pieces (Clarke 1998c, 178f.). Fig. 117. Some of the unworked pebbles and cobbles that were found during the excavation. The upper and lower left specimens have obviously been exposed to fire.

8.4.2.8 Anvil stone? SF428 is a rectangular piece of fine-grained, low-grade metamorphic quartz sandstone or quartzite. It has a square section with side lengths between 68 and 79 mm. The terminal ends are broken off, and one end appears to have been flaked. The edges are worn and indicate that the stone may have been used as an anvil.

material was identified as amphibolite. Depending on the orientation, the fragment could be interpreted as a base fragment of a four-sided vessel or alternatively as a body fragment of a cylindrical miniature vessel. However, given the small thickness of the wall and the rather untypical raw material, it may be part of a different object than a vessel.

8.8.2.9 Roof tile Four roof tile fragments were found in the upper horizons of trench 1 and 2, documenting the later use of the site. Two pieces of roof tiles made of mica-rich red sandstone were found in adjacent grid squares within the topsoil of trench 1 (SF090, SF091; Fig. 118). The larger fragment is broken across the perforation through which it was nailed to the batten. The two other fragments, SF118, were found together in the upper fill of the causeway [C2001] and are both made of grey sandstone that is rich in mica and limonite (Fig. 119).

8.4.2.7 Unworked pebbles and cobbles A larger number of unworked pebbles and cobbles was retrieved from [C1004], [C1005] and [C1010] (Fig. 117). They range from 20 to 76 mm in diameter, with diameters of 40–50 mm predominating. Two pebbles, both retrieved from [C1004] and both part of bulk finds FN201 and FN246, show possible traces of red or brownish paint, but these are very faint and cannot be identified with certainty as anthropogenic modifications. A number of pebbles, including some of the largest pieces, are blackened and fire-cracked and seem to have been exposed to fire. The pebbles represent a variety of rock types, but all are relatively bright,

8.4.3 Unclassified stone finds A number of finds cannot be classified into one of the groups discussed, mainly because of their fragmented state. A cobble fragment from FN160 can be interpreted as a D-shaped quern rubber, quern or anvil stone fragment. Three cobble flakes (FN277, FN448, FN450) may have split off cobble pounders during use. SF082

Fig. 119. Roof tile fragments (SF118) from trench 2.

Fig. 118. Roof tile fragments (SF090, SF091) from trench 1. 79

is a larger, ovoid hornblendite cobble fragment with a very smooth surface and a striking speckled pattern. This fragment may have been used as a burnisher or grinder, although it does not show clear traces of use. Moreover, as this fragment was retrieved from the topsoil of trench 1, it does not necessarily originate from the Iron Age contexts. SF206, SF472 and FN482 are fragments of sandstone slabs approximately 3 cm thick, with at least one smooth face. It is not clear whether these represent artefacts. Bulk find FN277 ([C1004]) contained a small, unworked piece of light grey fine- to medium-grained steatite. This might indicate the local production of steatite objects or, more likely perhaps, steatite-tempered pottery.

FN402, were retrieved from the rubble layers [C1006] and [C1007]. It is possible that these rubbers represent residual artefacts that had been re-used in the walls of a collapsed structure. However, we cannot rule out the possibility that D-shaped quern rubbers were still in use at the Law Ting Holm during the Middle or Late Iron Age, either for grinding cereals or for other purposes. The same problem applies to the rectangle found. Rectangles, flaked bars and ard points, all of which are believed to represent tillage tools, are among the most commonly found stone tools at prehistoric sites on the Northern Isles. However, the share of flaked blanks in the overall composition is observed to have decreased rapidly during the Iron Age. There is some uncertainty as to when flaked blanks ceased to be made and used, as most examples from Iron Age assemblages have been found at multiperiod sites and may hence be residual. Clarke (2006, 126) believes that the production and use of stone tillage tools stopped during or after the Early Iron Age, although it is not entirely clear why she thinks “the contexts of the flaked stone bars [from the broch sites Howe and Bu] would suggest that they were not used as tools of tillage”. Unfortunately, the rectangle from the Law Ting Holm was not found in situ. It is, however, quite likely that it was retrieved from one of the excavated rubble layers, and hence it may be residual as well. The presence of probable residual artefacts in the stone tool assemblage from the Law Ting Holm could indicate an earlier settlement phase, the remains of which may still lie hidden below the final excavated level. It is, however, noteworthy that the pottery assemblage has not yielded evidence of Bronze Age or Early Iron Age activities. Older stone artefacts may therefore also have been taken to the site as building materials.

8.4.4 Discussion As noted before, there are no apparent differences in the compositions of the stone assemblages from the individual contexts, and the whole assemblage from trench 1 can reasonably be considered a single unit. This assessment is consistent with the other artefactual evidence. Given the wide time span to which most of the stone tool types date, it is difficult to date individual stone tools based on their morphology. The composition of stone assemblages, however, has been attributed a certain chronological value (Clarke 2006, 112ff.). It is therefore rewarding to compare the assemblage from Tingwall with that of other prehistoric sites in Shetland. The most noteworthy characteristic of the stone assemblage from the Law Ting Holm is the strong dominance of cobble tools over flaked and chipped artefacts. This is rather typical for Late Iron Age assemblages (Clarke 2006, 126). It is interesting to note that the cobble tool assemblage includes a side-faceted cobble, a type that is best known from the broch site at Scalloway, only a few kilometres from the Law Ting Holm. The occurrence of perforated objects, namely a bead, a whorl and two discs, as well as small sandstone discs with partially ground faces and possible whetstones, all add up to form an image of a domestic stone tool assemblage typical of the Late Iron Age. However, there are some elements that do not fit in with this dating very well. This is especially true of the possible quern rubbers. D-shaped quern rubbers are commonly found in Late Bronze Age/Early Iron Age assemblages, such as at Bayanne on Yell (Clarke, pers. comm. 18-9-2013), but seem to have disappeared in the Late Iron Age as rotary querns became more common. Quern rubbers from later contexts generally appear to have been re-deposited or re-used as building material (Clarke 1998d; 1999, 160). It is noteworthy that three of the six quern rubbers from the Law Ting Holm, including the two largest fragments, SF377 and

8.4.5 Catalogue of stone artefacts - (Fig.115, Plate 1.1) stray find Tapering phyllite bar with a D-shaped section. Traces of hafting exist across the upper half. The flake damage on the distal edge may be modern. Found at the lakeside on the Holm, most likely from the dump of the excavation. 198 × 116 × 40 mm 1,250 g FN24 [C1000]; H104 Elongated grinder/pounder with square section, heavily pecked at the ends, flaked at one end. Fine-grained granite or recrystallised arcosic sandstone. 94 × 62 × 63 mm 702 g SF080 (Fig. 112) [C1000]; K108 Pointed end of an elongated ovoid cobble tool with flattened sides, smooth surfaces; possibly used as whetstone or burnisher. Quartzite or heavily recrystallised quartz sandstone. 52 × 43 × 23 mm 64 g SF082 [C1000]; L108 Fragment of a flattened ovoid hornblendite cobble with very smooth faces and a D-shaped cross-section. Possibly used as a burnisher or grinder, though there are no clear traces of use. 79 × 93 × 42 mm 441 g

80

81

82

with muscovite. 82 × 50 × 27 mm

SF090 (Fig. 118) [C1000]; L111 Piece of roof tile made of mica-rich red sandstone. 57 × 52 × 6 mm 27 g

198 g

SF191 [C1004]; H103 Grinder fragment with faceted ground faces. Fine-grained granite. 84 × 58 × 60 mm 293 g

SF091 (Fig. 118) [C1000]; L111 Central piece of roof tile made of mica-rich red sandstone, broken across perforation. 106 × 75 × 8 mm 103 g

FN194 [C1004]; K105 Piece of fine-grained pink phyllite with quartz components. Very soft material, heavily abraded, most likely burnt. 23 × 21 × 10 mm 6g

FN117 (Plate 1.2) [C1001]; J–K104 Subcircular stone disc, partly ground along the edges, with a rectangular cross section. Quartz sandstone with muscovite. 48 × 48 × 13 mm 55 g

SF199 [C1004]; G103 Grinder fragment with small ground faces on opposite sides. Possibly broken through heavy stroke. Quartzite with mica (muscovite). 91 × 80 × 53 mm 600 g

SF118 (Fig. 119) [C2001] Roof tile fragment made of mica-rich grey sandstone with limonite. 101 × 89 × 11 mm 177 g

FN201 (Fig. 117) [C1004]; J104 Fragment of white ovoid pebble, possibly fire-cracked. Crystal quartzite. 48 × 37 × 32 mm 71 g

SF118 (Fig.119) [C2001] Rectangular roof tile fragment made of mica-rich grey sandstone with limonite. 151 × 118 × 11 mm 413 g

FN202 (Fig. 112) [C1004]; G104 Fragment of an elongated ovoid cobble of dark red heterogeneous sandstone. Smooth surface, partially hollowed. No clear traces of use, but may have been used as a whetstone. 87 × 36 × 24 mm 101 g

SF126 (Fig. 116; Plate 1.4) [C1004]; J100 Nearly complete perforated stone disc made of calc-silicate rock (gneiss). Square in shape with rounded edges modified by flaking and grinding and has a drilled hole with a diameter of 23 mm. 155 × 160 × 22 mm 628 g

SF206 [C1004]; H105 Rectangular piece of a sandstone slab with smooth flat faces. Most likely an artefact. Fine-grained arcosic sandstone with muscovite. 68 × 54 × 34 mm 208 g

FN129 [C1004]; J101 Grinder fragment with faceted ground faces. Coarse quartz sandstone with muscovite and various quartz components. 92 × 85 × 47 mm 518 g

SF218 [C1004]; J105 Grinder/pounder with faceted ground faces, flaked on one side. Quartzite (possibly vein quartz). 92 × 90 × 61 mm 749 g

FN129 (Plate 2.1) [C1004]; J101 Fragment of perforated stone disc, broken across the perforation. Original diameter of approximately 160 mm. The diameter of the perforation is 35 mm. Presumably a square shape with rounded edges, ground along the edges to create a D-shaped profile. Calc-silicate rock (gneiss) with limonite. 115 × 80 × 11 mm 112 g

FN235 (Plate 2.4) [C1004]; K110 Body fragment of a round steatite vessel with a wall thickness of 12 to 15 mm. Medium- to coarse-grained dark grey steatite with very smooth burnished surfaces and traces of black crust on both sides. 75 × 60 × 14 mm 59 g

SF131 [C1004]; K101 Complete grinder with faceted ground faces. Fine-grained granite or recrystallised arcosic sandstone. 94 × 98 × 82 mm 1,159 g

FN246 (Fig. 117) [C1004]; H108 Fragment of a larger white quartzite pebble with a flat face. 52 × 48 × 28 mm 87 g

FN145 (Plate 2.6) [C1004]; J104 Base fragment of a round vessel made of phyllite/schist with a wall thickness of 9 mm. Light grey fine-grained material. 55 × 30 × 13 mm 22 g

FN252 [C1004]; H109 Circular pinkish-grey pebble with flattened faces, possibly used as burnisher. Aplitic granite. 59 × 57 × 18 mm 101 g

FN160 [C1004]; I102 Part of a large cobble with two perpendicular smooth faces, one flat and the other curved. Possibly part of a D-shaped quern rubber, quern or anvil stone. Granitic gneiss? Contains biotite and muscovite. 60 × 59 × 69 mm 294 g

SF254 [C1004]; I111 One half of a circular or ovoid white pebble with flattened faces. Coarse-grained quartzite. 58 × 29 × 29 mm 89 g

SF181 (Plate 2.2) [C1004]; K103 Steatite whorl with a biconical section. Reddish grey coarse-grained steatite. The diameter of the perforation is 16 mm. 46 × 35 × 16 mm 36 g

SF257 [C1004]; H109–110 Fragment of a quern rubber with a D-shaped section. Coarse-grained arcosic quartz sandstone. 151 × 81 × 48 mm 855 g

SF183 [C1004]; J102 Complete grinder/pounder with faceted ground faces and one end flaked. Quartzite with rounded, bluish grey mineral components 108 × 85 × 64 mm 834 g

SF258 (Plate 2.3) [C1004]; H109–110 Complete bead made of red sandstone. The perforation diameter is 9 mm. Heavily compacted sandstone with unidentified black rounded mineral components. 22 × 22 × 15 mm 9g

SF190 (Fig. 112) [C1004]; G103 Elongated cobble tool with an oval cross section and parallel flattened sides. Smooth surfaces on the broad sides, pecked along the edge. A pounder, possibly also used as a burnisher. Quartz sandstone

SF269 (Plate 2.5) [C1004]; G108 Body fragment of a thick-walled (18–23 mm), round steatite vessel. Light grey, fine- to medium-grained steatite with carbonate,

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reducingly fired. 87 × 55 × 22 mm

FN324 [C1005]; K102 Elongated, oval, greyish pebble, broken along its length. Granodiorite gneiss. 55 × 28 × 19 mm 29 g

145 g

FN270 (Plate 2.7) [C1004]; G110 Cylindrical, worked piece of amphibolite, 6–7 mm thick. Possibly a base fragment of a rectangular vessel? Coarse surface on the outside, smooth on the inside, with diagonal tooling. 32 × 27 × 9 mm 11 g

FN325 [C1005]; L102 Ovoid white quartzite pebble. 37 × 29 × 19 mm 32 g

SF273 [C1004]; I109 Small subcircular stone disc, partially flaked along the edges. Quartz sandstone with muscovite. 45 × 43 × 11 mm 28 g

FN325 [C1005]; L102 Ovoid white quartzite pebble. 29 × 20 × 18 mm 14 g SF330 [C1005]; K107 Part of an ovoid cobble with fire-cracked flat faces. Quartzite with atypical mineral and quartz components. 73 × 55 × 36 mm 248 g

FN277 [C1004]; I110 White cobble flake. Coarse-grained quartzite. 54 × 42 × 31 mm 62 g FN277 [C1004]; I110 Piece of fine- to medium-grained light grey steatite with many voids; very soapy. 39 × 26 × 19 mm 20 g

FN334 [C1005]; J108 Fragment of greyish-brown pebble, possibly broken due to heat? Low-grade metamorphic quartz sandstone or quartzite with coarse rounded quartz elements. 76 × 41 × 50 mm 163 g

SF279 [C1004]; H110 Oval cream-white pebble with flat faces, possibly used as burnisher. Granite. 58 × 45 × 21 mm 84 g

SF346 (Plate 1.3) [C1005]; I108 Circular stone disc, partly flaked along the edge. Quartz phyllite. 64 × 63 × 10 mm 71 g

FN280 [C1004]; spoil heap Large fragment of a saddle quern made of coarse-grained rock with quartz and feldspar (possibly granite). 197 × 162 × 141 mm 7,230 g

FN356 [C1005]; L101 Orange-greyish ovoid pebble fragment; not an obvious artefact. Granite gneiss with quartz mobilisates. 39 × 29 × 16 mm 23 g

FN281 [C1004]; spoil heap Fragment of a flat-faced, elongated pounder, flaked and pecked at one end (the other side is broken). Low-grade metamorphic quartzite with rounded quartz components. 97 × 72 × 44 mm 451 g

SF377 [C1006]; J100 Large fragment of a quern rubber with a D-shaped section. Coarsegrained arcosic quartz sandstone. 203 × 96 × 82 mm 2,140 g SF381 (Fig. 113) [C1006]; J102 Fragment of a quern with right-angled sides. Smooth and slightly hollowed; a ground face on one side; the other faces straight or broken. Heavily burnt. Fine-grained granite. 129 × 104 × 124 mm 2,610 g

FN281 [C1004]; spoil heap Fragmented grinder/pounder with a faceted face showing traces of pecking. Fine-grained quartzite. 108 × 94 × 52 mm 523 g SF288 [C1005]; L107 Complete grinder with faceted ground faces. Granite. 97 × 96 × 58 mm 803 g

FN390 [C1006]; J100 Slice of a quern rubber with a D-shaped section. Medium-grained quartzite with feldspar. 108 × 71 × 40 mm 409 g

SF289 [C1005]; L108 Grinder/pounder with faceted ground faces and several larger flake negatives. Quartzite. 87 × 84 × 67 mm 683 g

FN402 [C1007]; G111 Fragment of a quern rubber with a D-shaped section. Coarse-grained arcosic quartz sandstone. 204 × 142 × 54 mm 2,369 g

SF301 [C1005]; H107 Complete grinder with faceted ground faces. Low-grade metamorphic quartzite with uncrystallised quartz sandstone. 79 × 75 × 64 mm 569 g

SF407 [C1010]; J100 Complete grinder/pounder with ground faceted faces, flaked on one side. Coarse-grained quartzite with mica and rounded bluish-grey quartz components. 80 × 80 × 74 mm 656 g

SF302 [C1005];K105 Major part of an ovoid, flat-faced, white pebble. Quartzite with mica. 50 × 47 × 26 mm 90 g

SF415 [C1010]; J101 Elongated pounder fragment, broken lengthwise, pecked and flaked at the narrow end. Coarse-grained quartzite with rounded quartz components. 154 × 75 × 41 mm 664 g

FN303 [C1005]; K105 Fragment of a white, flattened, oval-shaped pebble, possibly firecracked. Crystal quartzite with mica. 40 × 41 × 22 mm 45 g

FN427 [C1010]; K103 Fragment of a flattened, oval-shaped, greyish pebble. Fine-grained quartzite or granite gneiss. 74 × 40 × 30 mm 124 g

FN307 [C1005]; L106 Fragment of a small, white pebble; not an obvious artefact. Coarsegrained quartzite. 25 × 24 × 14 mm 9g

SF428 [C1010]; H102 Fine-grained, low-grade metamorphic quartz sandstone or quartzite

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determine the chemical composition of the samples (metal, glass) and from which stage in the production process they were (smelting or forging). An initial macroscopic evaluation indicated that the slag finds were most likely to be the remains of iron smelting and/or iron forging. Further analysis of polished sections, using reflected-light microscopy, was required to confirm this assumption. After the macroscopic evaluation of the total volume of finds, a set of seven slag fragments was selected for detailed microscopic evaluation. Several other pieces which were of interest for the understanding of the whole find group were included in the evaluation, but did not undergo microscopic analysis.

rock with a square section; ends broken, one end presumably flaked, worn edges. Possibly used as an anvil stone. 137 × 87 × 81 mm 1,710 g FN444 spoil heap Fragment of a quern rubber with a D-shaped section. Arcosic quartz sandstone. 197 × 119 × 82 mm 1,943 g FN448 [C1010]; I106 Cobble flake. Fine-grained granite. 55 × 33 × 9 mm 21 g FN450 [C1010]; G107 Cobble flake. Amphibolite/hornblendite. 61 × 58 × 21 mm 99 g SF462 [C1010]; J107 Grinder/pounder fragment with smoothly ground band, heavily flaked and broken prior to being discarded. Coarse-grained quartzite. 78 × 65 × 69 mm 522 g

8.5.1 Sampling The selected fragments were cleaned and photographed. Specific sampling points were then selected, based on the significance of the fragments and their general state of preservation. A water-cooled rock-saw was used to make sections, which were then embedded in epoxide resin. After the resin had hardened, the sections were ground and polished with SiC paper (180, 600, 1200, 2500 and 4000 grit size).

FN466 [C1010]; L108 Fragment of a reddish-brown, fine-grained quartzite pebble, broken. 44 × 25 × 23 mm 38 g SF472 [C1010]; H110 Sandstone slab with a very smooth face. Sandstone with muscovite. 129 × 137 × 33 mm 850 g FN482 [C1010]; K–L107 Grinder fragment, possibly burnt. Aplitic granite. 105 × 68 × 28 mm 285 g

8.5.2 Analysis The techno-typological analysis of the slag is based on the methods of classical metallography and ore-microscopy (Schumann 1990), but also makes use of terminology adopted from descriptions of the characteristics of archaeometallurgical remains (Sperl 1980; Kronz and Keesmann 2004), which is uncommon in modern material science. A standard reflected-light microscope (Olympus BX51, 25×, 50×, 100×, 200×, 500× and 1000× magnification) was used for evaluation and documentation. The image-processing software analySIS-docu (Olympus) was used to analyse the samples. Figures and plates were created using CorelDRAW X3. Sample descriptions comprise an initial macroscopic description, followed by a microscopic description and evaluation.

FN482 [C1010]; K–L107 Small, elongated pebble with an oval cross section. Not an obvious artefact. Aplitic granite. 37 × 25 × 14 mm 18 g FN482 [C1010]; K–L107 Rectangular fragment of a sandstone slab. Doubtful artefact. Sandstone with muscovite. 35 × 32 × 28 mm 45 g FN484 [C1010]; J106 Fragment of a quern rubber with a D-shaped section. Arcosic quartz-sandstone with rounded quartz and feldspar components. 99 × 73 × 76 mm 655 g

8.4.6 Acknowledgements I am most grateful to Michael Götzinger of the University of Vienna’s Institute of Mineralogy and Crystallography for the petrographic analysis of the stone artefacts and to Amanda Forster for information on the steatite whorl. I would also like to thank Ann Clarke for commenting on the draft version of this report and pointing out some inconsistencies that would not have occurred to me.

8.5.3 Observation 8.5.3.1 FN329 [C1005] (Plate 3.1–5) A small fragment of tapped slag. Large parts of the original top-surface are preserved, showing a clear flow texture. The bottom surface is smooth and clean with no inclusions. The microstructure is characterized by long crystals of fayalite superposed by dendrites of wustite. Numerous single iron grains are visible even at lower magnification (25×). In many areas of the polished section it is difficult to identify single phases at low magnification, due to the presence of numerous gas cavities.

8.5 Archaeometallurgical analysis By Erich Nau As part of the current research project based on excavations at Law Ting Holm / Shetland a quantity of slag finds was investigated at the archaeo-metallurgical laboratory of the Vienna Institute for Archaeological Science (VIAS). The purpose of the analysis was to

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sand grains. The top surface indicates a flow texture with no clear direction of flow. After sampling, the cross-section appears very dense, with no gas cavities visible. The microstructure is characterized by dendrites of wustite and long crystals of fayalite embedded in a glassy matrix. Several superimposed layers of slag flow can be distinguished on the basis of bands of wustite grains (Plate 6.3, 6.5), indicating that the sample is part of a tapped slag. The lower part of the sample seems to consist only of a glassy matrix with no typical wustite and fayalite content, possibly indicating that this area was once part of a molten furnace wall.

8.5.3.2 SF351 [C1005] (Plate 3.6–10) A fragment of tapped slag with the original top and bottom surfaces preserved. The top surface shows a clear flow texture. The bottom surface is smooth and clean with no inclusions. The entire polished section has a porous appearance, with numerous small gas cavities. The microstructure is characterized by long crystals of fayalite and small dendrites of wustite embedded in a glassy matrix. The clear identification of phases is complicated by the porous nature of the sample. Seams between single superimposed layers of slag are visible as bands of bubbles. 8.5.3.3 FN391 [C1006] (Plate 4.1–5) An entirely preserved piece of slag with no visible fractures. Small areas of the surface show an indistinct flow structure, with no clear flow direction. This slag probably did not flow out during slag tapping, but solidified inside the furnace. Parts of the surface have negative imprints showing the distinct pattern of annual rings. These would have been made by the charcoal (or wood) which was used as fuel in the furnace. The microstructure appears very homogeneous and is characterized by crystals of fayalite embedded in a glassy matrix. In some areas, dendrites of wustite are visible between single fayalite crystals, but do not intersect with them.

8.5.3.7 FN128 [C1004] (Plate 6.1–5) An amorphous piece of slag with a very rusty surface, showing almost no clear details. Some areas may possibly be interpreted as imprints of charcoal. The piece is very light, implying a very porous structure. The cross section has a highly porous appearance, with numerous large cavities. The actual slag forms a coarse network around the cavities. The microstructure is mainly characterized by a glassy matrix. Only a few crystals of fayalite are present; in some gaps between fayalite crystals, dendrites of wustite can be seen. Numerous single grains of metallic iron are visible all over the sample. The following samples were not examined microscopically. SF238 [C1004] (Plate 6.6) A fragment of furnace lining, with vitrified clay and possibly slag on the inside of the lining, and burned clay on the outside. Smooth transitions between the inside and outside textures. FN158 [C1004] (Plate 6.7) A fragment of furnace lining, with vitrified clay and possibly slag on the inside of the lining, and burned clay with several bigger stone inclusions (up to 0.5 cm) on the outside. Smooth transitions between the inside and outside textures. SF430 [C1010] (Plate 6.8) A plano-convex slag cake with the original surface preserved almost all round. It has the typical shape of a smithing slag (negative of a smithing hearth). FN157 [C1004] (Plate 6.9) A fragment of tapped slag; parts of the original surface with a typical flow texture are preserved. The distribution of small cavities in the fractured surface indicates several layers of slag flow. FN136 [C1004] (Plate 6.10) A slightly plano-convex piece of slag, with an irregular appearance on the bottom surface, showing scattered inclusions. This could be either furnace slag or smithing slag.

8.5.3.4 SF414 [C1010] (Plate 4.6–10) A slightly plano-convex piece of slag which seems to be entirely preserved, no fractured surfaces being evident. Its entire surface is irregular. Its shape may represent the negative of a smithing hearth. The microstructure appears very homogeneous and is characterized by coarse fayalite crystals and coarse globular wustite (possibly hammer scale?); dendrites of wustite are rare. Numerous cavities are visible all over the section. 8.5.3.5 FN342 [C1005] (Plate 5.1–5) An amorphous slag fragment with all its original surfaces entirely removed by secondary fracturing. The fractured surfaces appear very dense with almost no gas cavities visible. A dense network of coarse-grained globular wustite characterizes the microstructure; only very few typical fayalite crystals are visible. The globular wustite grains are interlaced with very small gas cavities. A high iron content is evident from the dominance of wustite in this sample, but only very few grains of metallic iron are present. 8.5.3.6 SF420 [C1010] (Plate 5.6–10) An amorphous slag fragment, with only small parts of the original surface preserved. The bottom surface appears to be sintered and shows several inclusions of

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some indication on the internal diameter of the smithing hearth, and are similar in size to the slag cakes from Kebister (Spearman 1999). Of the microscopically analysed samples, one (SF414 [C1010], Plate 4) may possibly also be part of a slag-cake. However, the analysis does not provide a clear differentiation from furnace slag, as the mineralogical phases of the two slag types are generally very similar.There are also several pieces of furnace lining or furnace brick present amongst the slag finds, of which two are included amongst the samples which were not microscopically analysed (SF238 [C1004], FN158 [C1004], Plate 6.6–7). The brick is vitrified on the side that would have faced the furnace and burned on the outer side. A clear differentiation between the linings of ferrous and non-ferrous metalwork furnaces and the linings of domestic hearths is not possible, but the fact that these fragments were found alongside iron-working slags and that their inner faces are vitrified and slagged provides a strong indication that they are the remains of bloomery furnaces. Their presence, and the presence of tapped slags, allows the possible types of furnace used in Law Ting Holm to be narrowed down: probably they were some kind of clay-built shaft furnace, either free-standing or partly embanked (Pleiner 2000). The mixture of furnace-, tapped- and smithing slags, together with furnace bricks, and their generally high degree of fragmentation, indicate that this was a secondary deposition. It was probably some kind of spoil heap or pit, possibly in the close vicinity of an iron workshop which carried out the entire range of iron working, from smelting the iron ore and refining the iron bloom to the production of wrought iron or even finished products. The evidence of both iron production and iron working from Law Ting Holm is very similar to that from the nearby sites of Kebister (Spearman 1999) and Scalloway (Campbell 1998), whereas the site at Scatness (McDonnel et al. 2010) only yielded evidence of smithing activities.

8.5.4 Interpretation The slag finds from Law Ting Holm are clearly the remains of iron working. This is evident from the common appearance of rust and the occurrence of characteristic mineralogical phases (wustite and fayalite), as well as from inclusions of metallic iron in several samples (Sperl 1980). Overall, the unearthed pieces are mostly small fragments where only a few original surfaces are sufficiently well preserved to allow clear macroscopic classification. Most of the samples selected for microscopic analysis did have well-preserved original surfaces and could therefore be pre-classified. Furnace-, tappedand smithing slags were identified (Pleiner 2000; Pleiner 2006), indicating the presence of both iron production, in bloomery furnaces, and smithing activities. The microscopic analysis allowed a more precise classification, and two types of furnace slag were defined. The first is very compact, with almost no cavities, showing an iron-rich microstructure, mainly consisting of globular wustite and a few fayalite crystals in a glassy matrix (FN342 [C1005], Plate 5). This iron-rich type was probably produced during an early stage of the smelting process (primary slag) when the ore had become molten but the reduction to metallic iron had not yet taken place. This type of slag is possibly the result of unsuccessful smelting attempts. The second type of furnace slag (FN391 [C1006], FN128 [C1004], Plates 4 and 6) is characterized by its light weight and numerous gas cavities. The microstructure mainly consists of the glassy matrix with only a few fayalite crystals and dendrites of wustite, indicating a low iron content. This type probably belonged to the portion of slag which remained at the bottom of a bloomery furnace and could not be drained out. The reducing conditions inside the furnace would account for the very low iron content in these samples. Tapped slags represent the majority of the pieces which are clearly definable by macroscopic examination. The analysed samples of this type (FN329 [C1005], SF351 and SF420 [C1010], Plates 3 and 5) show an homogeneous microstructure characterized by long crystals of fayalite and long dendrites of wustite intersecting each other. This microstructure exemplifies the ideal composition of iron-silicate (fayalitic) slag (Kronz and Keesmann 2004) which forms at the lowest melting point necessary to drain the slag and separate it from metallic iron. Smithing activities are represented by the slag type which is its typical by-product: so-called “slag-cakes.” These are pieces of slag which have taken the negative shape of the smithing hearth (Pleiner 2006). One probable and one possible example of a slag cake are among the samples which were not examined microscopically (SF430 [C1010], FN136 [C1004], Plate 6.8 and 6.10 respectively). They have a diameter of between 9 cm and 10 cm, providing

8.6 Metal artefacts By Joris Coolen and Natascha Mehler Four metal artefacts were found in trench 1. They are likely of prehistoric date and came from layers that yielded rich archaeological material from that period. All metal artefacts were restored at the laboratory of the Department of Prehistory and Historical Archaeology, University of Vienna. Two objects were made of iron and are now heavily corroded. SF250 from [C1004] (G106) is an S-shaped object and resembles a fish-hook (length 25 mm, width 13 mm, thickness 4 mm) (Fig. 120). FN306 from [C1005] (I107) looks like an iron bolt with the remnants of applied sheet metal (length 45 mm, width 17 mm, thickness 15 mm) (Fig. 121). Two very well-preserved non-ferrous metal artefacts were found. SF231 from [C1004] (I107) is a small

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Fig. 121. Unknown iron object FN306 from [C1005].

Fig. 120. SF250, an S-shaped iron object from [C1004].

Fig. 123. Small silver spiral (SF361) from [C1005].

Without further analysis it must remain unclear whether the iron and non-ferrous objects were manufactured at the site. As chapters 6 and 8.5 have shown, iron working took place at the Law Ting Holm and it may well be that SF250 and SF344 were made at the site, although no evidence of non-ferrous metalworking was discovered in trench 1. Iron Age iron production has been proved to have taken place in Shetland at Kebister (Spearman 1999) and at Scalloway (Sharples 1998, 123–125), for example. At Old Scatness, evidence of non-ferrous metalworking was found in contexts dating from the Pictish period (McDonnell et al. 2010, 331). No silver deposits are known in Shetland (McDonnell and Dockrill 2005, 203) but evidence of silver smithing was found at Old Scatness (McDonnell and Dockrill 2005, 207) and at Scalloway (Campbell 1998).

Fig. 122. SF231 from [C1004], a small copper alloy ringlet.

copper alloy ringlet with a diameter of 15 mm. Its opening measures ca. 2.4 mm (Fig. 122). SF361, found in [C1005] (K111), is a small silver spiral of outstanding quality with an outer diameter of 14 mm. It comprises 3 ½ windings of thin silver wire (0.8–0.9 mm in thickness). At the centre of the spiral the wire ends in a point, while at the outside it appears to be broken off (Fig. 123).

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9

The animal bones

By Günther Karl Kunst 9.1 General characteristics From trench 1, 4,581 bone specimens with a total weight of 14,937.6 g, resulting from 295 archaeological samples, were studied. Of these, 3,038 specimens with a total weight of 13,615 g were identified as belonging to a certain taxonomic level or size group: given the fact that domestic mammals are dominant throughout all samples, 176 and 110 fragments with the respective total weights of 499.9 g and 100 g were ascribed to the groups “cattle-size” and “sheep/pig-size”. This procedure was carried out, somewhat arbitrarily, for fragments which could be attributed to element or element groups, but not to the species/genus level proper. Other specimens allowed for the attribution to an element group, but not for a clear specification of size. Given the widespread occurrence of remains of neonate or very young cattle, it was not always possible to draw a clear line between these and the smaller domestic mammals. There are also several worked pieces which were made from mammal bones, but could not be specified further. In all, 66.3 % of the total number and 91.1 % of the total weight were “identified” or categorized in some way. 2,736 remains (12,981.2 g) could be ascribed to more defined taxonomic levels (including birds and fish), corresponding to 59.7 % (number) and 86.9 % (weight) of the total assemblage. From these figures alone it becomes clear that size is a critical factor in identification, but also that the material is rather smallsized. Average specimen weight is 4.5 g in the categorized sub-sample (including the bones attributed to “size-groups” only), and 3.3 g for all remains. Also, among the “identified” remains (average specimen weight 4.7 g), only 17 specimens weigh more than 40 g: these are larger fragments (skull parts, scapula, pelvis) of cattle, or whale bones, with exceptional greatest lengths of more than 10 cm. About 60 % of all determined specimens, however, weigh less than 3.0 g. Apparently, the taphonomic conditions at Tingwall favoured small specimens. This fact is likely to have some influence on species and element composition. The bone surfaces exhibit different shades of brown and generally allow for a clear identification of stains caused by heat influence, and other alterations. There are what appear to be “structural” colours, however, mainly a dark brown, especially among bones from very young mammals, which may mimic heat charring. The conditions of bone surfaces may vary even within samples, but only a small number of the specimens look abraded or otherwise heavily deteriorated. This means that anthropogenic marks (cuts, chops) remain recognizable in most cases. From trench 2, only seven remains with a total weight of 69.6 g were available, five of which (12.9 g) were identified. The finds can be attributed to cattle, sheep

Fig. 124. Two fragments of whale bone, SF328. and cattle-size. Most noteworthy, given the general rarity of this group in trench 1, is a single fish vertebra. If not indicated otherwise, all the following remarks refer to trench 1. 9.2 Species composition The major domestic mammals, cattle, ovicaprines and pig, are consistently present throughout practically all samples. Among the ovicaprines, only the sheep was definitely identified, which accords with all available archaeozoological literature on the Shetland Islands (e.g. Bond et al. 2010). It may well be that this group as a whole can be attributed to the sheep, and that the goat is in fact absent. Equids, specifically the horse, are represented by 12 remains from 11 samples. A carnivore, probably the domestic dog, is represented by a single find. Four fragments with either a thick cortical layer and adherent cancellous (spongy) tissue, or cancellous tissue alone, were identified as cetacean bones, possibly from the jaw bone of a balaenid species (Fig. 124). Two fragments may result from seals; the specimens are very small and lack articulations or other characteristic landmarks, which makes a definite identification impossible. Together with the possible carnivore and some further dubious remains, these bones are summarized in the “mammals indet.” category. The absence or scarcity of seals, which runs somewhat counter to expectations, has been reported for other sites on the Northern and Western Isles as well (O’Sullivan 1998a; Bond et al. 2010). The five human remains stem from three samples and may result from one single juvenile skeleton. Among the vertebrates, wild birds form the only important natural resource. They are represented by 56 remains from 33 samples. However, 20 remains alone belong to a badly preserved partial skeleton, probably of a gull, found during the cleaning of a trench profile. The almost complete absence of fish 93

Taxa Bos Ovis Sus Equus cattle-size sheep/pig-size Cetaceans mammals indet. Homo birds fish Total NR3 - G3

number

weight (g)

%NR3

%G3

1,083 1,255 313 12 176 110 5 16 5 56 7 3,038 2,651

8,406.6 3,103.6 1,054.3 130.4 499.9 100 193.7 33.9 36.3 52.4 3.9 13,615 12,564.5

40.9 47.3 11.8 0.5 6.6 4.1 0.2 0.6 0.2 2.1 0.3 114.6 100.0

66.9 24.7 8.4 1.0 4.0 0.8 1.5 0.3 0.3 0.4 0.0 108.4 100.0

Table 11. Species composition at Law Ting Holm. remains – only seven fragments were collected – forms, arguably, one of the most outstanding features of the present assemblage. Although water-sieving was not used at the excavation, the collection of skeletal specimens, as can be seen by the composition of the samples, was carried out with great care, taking account even of minor fragments. It seems thus unlikely that either all fish remains were over-looked, or that fish were not represented by some larger elements which would have been collected anyhow. The scarcity of fish remains at Tingwall, therefore, appears to be a primary one (Table 11). As for the quantitative composition, values are best discussed in relation to the “domestic triad” of cattle, sheep and pig. If the so-called “size-group” specimens are excluded, the total number and weight for these three species put together are 2,651 and 12,564.5 g respectively. Due to fragmentation, the number of cattle has probably been under-estimated in the figures below: although some equid bones may be hidden in the cattle-size group, the majority of “equid” bones may in fact belong to Bos. The 110 specimens of the sheep/pig-size group, conceivably, belong in their majority to sheep. Leaving these caveats aside, if the number (NR3) and weight (G3) of the “domestic triad” are taken as 100 %, the respective percentage values for these three species are:

takes the third place both in number and weight. The weight-dominance of the cattle remains, a common feature in many archaeological situations due to their greater weight, can be regarded as comparatively moderate. This composition of the three main domesticates is not present in any of the archaeological horizons (Pictish-Late Norse) at Old Scatness, where cattle always forms the dominant element over sheep, while pig even reaches second place in the Pictish/Viking interface phase (Bond et al. 2010). The pattern observed at Tingwall, with the preponderance of sheep, should not be over-interpreted, however. It might well be a result of the taphonomic conditions, which obviously favoured small fragments, and of the author’s decision as to what to regard as identifiable and what not. The intra-site differences in the relative abundances of the main domesticates are not considered here; there are, however, cattle-dominated samples, and probably also contexts, at Tingwall as well. Among the remaining elements, it is only the birds which exhibit notable values as regards numbers (2.1 % of NR3), and equids and cetaceans as regards weight (1 and 1.5 % of G3, respectively). All other values observed fall below 1 %. 9.3 Observations on the domestic mammals 9.3.1 Age structure In examining the age structure of the domestic mammals at Tingwall, the same three criteria were used as at Old Scatness (Bond et al. 2010): percentage of neonate specimens, epiphyseal fusion, and eruption and wear of the lower dentition. A large percentage of the younger age classes, namely of neonate cattle remains, appears to be a common feature of assemblages from

Cattle: 40.9 % NR3, 66.9 % G3; Sheep: 47.3 % NR3, 24.7 % G3; Pig: 11.8 % NR3, 8.4 % G3. There is, therefore, a clear numerical dominance of sheep, which falls just short of 50 %, while pig

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Fig. 125. Bones of neonatal or foetal cattle; left: right rib FN461; left rib FN450; centre top: ilium sin. FN341, cutmark on dorsal rim; centre bottom: proximal phalanx FN447; calcaneus sin. FN328; left metatarsal FN162, lateral ray, dorsal view; right: left metacarpal FN293, both rays, dorsal view.

Fig. 126. Bones of very young cattle. From left to right: humerus sin. FN316, proximal fragment; proximal phalanx FN473; humerus dext. FN300; ulna sin. FN128; ulna sin. FN262; metatarsus dext. FN482, distal fragment.

the Western and Northern Scottish Isles, from the Bronze Age up to the Norse period. The explanations suggested include sampling and taphonomic biases, unfavourable environmental and economic conditions, and deliberate measures relating to herd management. The routine slaughter of very young calves is often regarded as a possible consequence or by-product of a husbandry regime relying on dairying. See Halstead (1998) and Mulville et al. (2005) for a comprehensive discussion of this issue.

metapodia must come from foetal individuals.” Due to the lack of clear discrimination criteria, the percentage of foetal bones is probably under-estimated at Tingwall. A further 63 bones and teeth were categorized in the “very young” (neonate and older) group, with skull parts as additional elements (Fig. 126). The percentage of the total fragment count of cattle is 4.5 % for the neonates/foetals, rising to 10.3 % if the “very young” group is added. This larger figure corresponds with the Pictish phase at Old Scatness, whereas in the Late Norse period neonates comprised nearly 25 % of the total NISP of cattle. Foetal/neonate or very young cattle remains appear to be consistently distributed throughout the material; they are present in 39 and 45 different samples, respectively. Sheep: Nine remains, comprising vertebrae, ribs and various extremity elements, exhibit close correspondence to a stillborn comparative specimen. If eight further long bones from very young specimens are added, the foetal/neonate remains make up 1.4 % of the sheep sample. In the Pictish and Viking phases at Old Scatness, similar results were obtained. The lower abundances of neonate sheep in comparison with those of cattle also conforms to the trends found at the majority of other sites of the region (Mulville et al. 2005). Pig: The only neonatal remains are three upper rib parts. They were assigned to this species on the basis of morphological details. There is one skull fragment which likewise results from a specimen of very young age. Together, these four bones make up 1.3 % of the total NISP. Pig neonate numbers at Tingwall appear a little higher than those for the Pictish period at Old Scatness, the only phase where neonate pig remains were observed. Most of the other small pig remains already fall into the juvenile stage proper (see below).

9.3.2 Occurrence of neonatal/foetal bones Neonate bones were identified by size, texture and fusion state, with the help of modern comparative specimens. Some of them may indeed include foetal remains. Cattle: As regards cattle, certain remains appeared considerably smaller than a comparative skeleton of 4–6 months of age, but not always quite as small as a foetal (8th-month) comparative specimen. These “very young” specimens may therefore include remains of neonate and foetal specimens, or animals which died within their first month(s). 49 remains were classified as neonatal or foetal; they comprise fragments of mandibles, loose teeth, vertebrae, ribs, shoulder and pelvic girdles, long bones, tarsals, metapodials and phalanges (Fig. 125). In some instances, even the third and fourth metapodials were still not fused to each other. According to Mulville et al. (2005), “Foetal bone is particularly easy to identify in the form of longitudinally unfused 3rd and 4th metapodia in cattle and sheep. The fusion of the diaphyses of 3rd and 4th metapodia in cattle begins at day 200 after conception and by day 210 this process should be completed (Prummel 1987a, Prummel 1987b). As the average gestation is c. 285 days any longitudinally unfused

95

Pig epiphysial fusion curve

100

100

90

90

80

80

70

70

60

60

% Fused

% Fused

Cattle epiphysial fusion curve

50 40

50 40 30

30

20

20

10

10

0 Birth

0 Prenatal

Birth

Early

Intermediate

Late

Early

Intermediate I Intermediate II

Late

Final

Final

Fusion stage

Fusion stage

Fig. 127. Cattle epiphysial fusion curve, showing percentage of elements fused at each fusion stage. Prenatal fusion stage is defined by unfused third and fourth metapodials.

Fig. 128. Pig epiphysial fusion curve, showing percentage of elements fused at each fusion stage.

9.3.3 Epiphyseal fusion The state of fusion in limb elements and vertebrae was recorded and grouped into stages as suggested by O’Connor (1989) and also as used in the Old Scatness report (Bond et al. 2010, 139ff.). This procedure gives only a relative picture of the ages at which animals died, as the exact timing of fusion in any position can vary greatly according to a number of factors. The fusion sequence, however, remains constant. According to the scheme presented by O’Connor, early, intermediate, late and final (except for pigs) fusion stages can be discerned. In the case of sheep and pig, the intermediate stage is further subdivided into stages I and II. The groupings used for Tingwall follow those given in the Old Scatness report, which were adapted from O’Connor (1989). However, a final stage, defined by fusion of vertebrae bodies, was used for pigs as well. A special case was presented by the occurrence of longitudinally unfused metapodial rays in cattle specimens, which indicated foetal individuals which died before birth. Therefore, an additional fusion stage (prenatal) was introduced for cattle, defined by the longitudinal fusion of ruminant metacarpal and metatarsal rays III and IV (Fig. 127). Fusing epiphyses were counted as fused and only whole ends of diaphyses were counted. Loose epiphyses were ignored. The number of fused epiphyses was then expressed as a percentage of the total number of all observed whole diaphyseal ends. Observations of fusion data appear sufficient for cattle (308) and sheep (288), but less so for the pigs (54). When the results are compared with the data for the different stages at Old Scatness (Bond et al. 2010, 139ff.), it can be seen that the database for Tingwall is larger than that for all phases from Old Scatness put together. The majority of pigs, apparently, did not survive beyond the “intermediate I” fusion stage, with 57 %

of the bones fused in the “early” group and only 7.1 % surviving into the “intermediate I” stage (Fig. 128). In this, Tingwall follows all horizons from Old Scatness, where only animals of slaughtering age, roughly up to the age of two years, were found to be present. As neonate remains are also scarce, that means that pigs were mostly produced elsewhere and only slaughter animals or their parts were brought to the site. At Tingwall it is only owing to the fused epiphyses of two long bones, one calcaneum and one proximal phalanx, that the curve shows an “upturn” after the “intermediate I” stage, indicating that a few individuals of breeding age were also present. A proximal humerus and a distal femur with their epiphyses just

Fig. 129. Typical remains of pig; from top to bottom, left: FN300, left maxillary bone with P4–M2; FN295, left mandible with M1,2; FN202, left mandible with P3,4; centre: FN297, humerus sin., adult, proximal part; FN328, right mandible with canine, male; FN327, metatarsal 4 (?), juvenile, with cut-marks; FN347, left mandible, juvenile, with D4; right: FN356, humerus sin., juvenile, distal part; FN375, femur dext., adult, distal part. 96

and, still more moderate, to the “late” (30.4 %) stage, to be followed by a noticeable upturn in the “final” stage (44.2 % fused). This upturn, again incompatible with the presence of a single population, is, by definition, exclusively caused by the presence of vertebral corpora with fused epiphyses. It consists of a sample of 70 corporal fragments, 31 of which were found un-fused. On the other hand, the slaughter or consumption of very young and young cattle is evidenced by the various skeletal elements the epiphyseal closure of which defines the stages “early” and “intermediate”. Thus, the possible distorting influence of skeletal part representation should be kept in mind. The sharp fall in the early stage and the presence of older individuals clearly points to a bimodal type of meat exploitation. It indicates that both beef and milk production were important elements of the cattle economy at Tingwall. There is no exact parallel among the fusion curves calculated for the different phases at Old Scatness. Common features are the fall between the “birth” and “early” fusion stages (all phases), and the existence of some upturn in the later stages in the Viking and Late Norse periods. In the Pictish and Viking phases at Old Scatness, this fall does not continue into the “intermediate” stage. In this respect, the emphasis on the consumption of prime beef, or the consumption characteristic of the assemblage in general, appears more accentuated at Tingwall.

Sheep epiphysial fusion curve

100 90 80

% Fused

70 60 50 40 30 20 10 0 Birth

Early

Intermediate I Intermediate II

Late

Final

Fusion stage

Fig. 130. Sheep epiphysial fusion curve, showing percentage of elements fused at each fusion stage.

fused (Fig. 129) indicate animals of about three and a half years of age at slaughter (Reichstein 1991). The absence of vertebrae with fused epiphyses reduces the “final” stage to zero. The presence of an “upturn” in the fusion graph, impossible within a single population, is an indication of the presence of a number of different populations. It is also noteworthy that the four bones “responsible” for the survival of the older stages result from the contexts [C1005], [C1006] and [C1010] (see below for the dentition data). Sheep fusion data shows a steady fall from the “early” to the “intermediate II” stages, with 35.3 % and 37.9 % of surviving animals in the “late” and “final” groups (Fig. 130). The slight drop off in the “early” group (82.2 %) makes it different from any of the periods at Old Scatness, where all animals survived into the “intermediate I” stage or even beyond (Late Norse). Apart from this difference, the pattern at Tingwall is somewhat intermediate between the Pictish and Viking phases at Old Scatness: here, “an emphasis on meat production in the Pictish phase, with a shift to a greater emphasis on wool production in the Viking phase” (Bond et al. 2010, 142) was observed. Therefore, a mixture of meat and wool appears likely for Tingwall as well. Here, the main drop off appears between the “intermediate” stages I (about one year old) and II, from 69.6% to 41.5 %; these animals are all likely to have produced some wool before their slaughter. The steady drop off between birth and “intermediate I” indicates the slaughter of lambs and young sheep of about one year old, indicating some emphasis on the consumption of prime lamb and mutton. In cattle, the special situation indicated by the presence of longitudinally unfused metapodials was already commented upon. Apart from this unequivocal evidence for foetal bones, a sharp fall is visible between “birth” and the “early” fusion stage, with only 60 % fused in this latter group. The drop off continues, less accentuated, into the “intermediate” (38.6 % fused)

9.3.4 Tooth eruption and attrition Due to the small number of lower tooth rows, age at death data from mandibles is much scarcer than from epiphysial fusion. Specimens used were mandibles containing DP4, P4 or M3 teeth or loose specimens of these categories. Wear stages of M1 and M2 were only used if their position could be derived from their morphology and size in pigs, and from their location in the mandible bone in ruminants. Wear stages were recorded according to Grant (1982) and all specimens were then, as far as possible, integrated into O’Connor’s (e.g. 1989; 2003) eruption and attrition stages: from loose teeth, the most likely mandible wear stage (MWS) was obtained from the data published in Grant (1982) (Table 12). In pigs, eight mandible fragments and three loose molars were amenable for age estimates. Of these, four specimens could be attributed to the “immature” stage with undeveloped or unworn M2. All the remaining five mandible fragments belong to the “subadult” group, which could be further specified into “subadult 1” for six specimens and “subadult 2” in one case. According to the age data published in Reichstein (1991), the mandibles are mostly from pigs slaughtered late in their first year or in the first half of their second year. Also, in the upper dentition, no specimens with the M3 in wear were found. There is, however, one maxilla from [C1005] with more heavily worn

97

Eruption and attrition stages after O’Connor 1991 Neonatal Juvenile ImmaSubadult ture 1 2 Pig Sheep Cattle

4

1 7

4 2 2

6 1 3

1 2

Adult

Elderly

1

2

3

7

6

3 8

4

Table 12. Tooth eruption and attrition. anterior molars which could belong to the older pigs represented by the long bones with fused epiphyses. Nevertheless, the overall picture roughly corresponds with the epiphysial pattern and with the conditions at Old Scatness (Bond et al. 2010, 143), where apparently “none of the animals was older than approximately two years at slaughter. It also appears unlikely that any were killed before 12 months old.” For sheep, the sample consists of five incomplete tooth rows and 19 loose teeth. They cover a wide range of stages, from a few finds in the “juvenile” (1) and “immature” (2) groups to the “subadult” (2) and finally the “adult” classes, to which the majority could be attributed. Far more than half (19) of all specimens belong to the three subgroups of the “adult” stages, with an almost even distribution. According to the age data published in Reichstein (1991), a few animals were slaughtered at the age of around six months and also in their second year, but most were slaughtered from their third year onwards. No molars belonging to elderly/ senile individuals could be found. These results appear somewhat to contradict the fusion data, which shows a more important culling of younger individuals and the main drop-off already occurring in the second year. Thus, the dental data implies a greater importance of wool production. It does not correspond to the Pictish wear and attrition patterns at Old Scatness, where the main fall-off occurred in the second half of the first and within the second year. There are some resemblances

to the Viking phase, where most animals were either slaughtered in the second half of the first year or at 4–6 years. In cattle, six mandible fragments and 22 isolated teeth could be analysed. In comparison with sheep, an even wider range of eruption and attrition stages is covered, and the distribution of the frequencies is clearly bipolar: four specimens alone fall into the “neonatal” (Fig. 131), seven into the “juvenile” and two into the “immature” classes. Only three specimens belong to the “subadult 1” stage, with the milk dentition still in use. Then there appears to be a gap, because the remaining specimens could be classified as either “adult 3” (8) or “elderly” (4). Even though these latter stages are exclusively based on the wear pattern of the M3, which may be unreliable due to environmental conditions, it is obvious that no older subadult or younger adult individuals are documented. The slaughter of elderly animals at the site is likewise evidenced by the presence of heavily worn maxillary toothrows (Fig. 132). That is, a major gap can be detected between the younger classes, well documented by dental eruption and wear of the milk dentition, and the advanced adult classes. Apparently, the dental remains testify to there being almost no animals slaughtered in the period of their best meat yield, at about 2–3 years of age. This is, by and large, consistent with the epiphysial closure pattern, and bipolarity is visible here as well. It may be a further indication of the possible importance of

Fig. 131. Right mandible of very young cattle F307, medial and lateral view; D2–D4 and fragment of M1 in crypt.

98

9.4 Taphonomic observations 9.4.1 Skeletal part representation The representation of skeletal parts may provide valuable clues concerning the use and discard patterns of animal carcasses and the functional background of assemblages. Skeletal parts differ in many ways, such as culinary relevance, amount of muscle attachment, durability against mechanical stress, overall size and determinability, which may all be responsible for anatomical biases within a given sample. Animal bone samples resulting from carcasses which have been processed and consumed are likely to exhibit certain trends regarding skeletal part representation. Here, this parameter was calculated by plotting the relative weight distribution of the skeletal parts of the sample against a comparative skeleton (Reichstein 1994).12 Deviations from the “natural” weight distribution in the sample indicate either loss or accumulation of elements or element groups, of course always in relation to the remaining parts of the skeleton. This method takes account of differential fragmentation, but not of the fact that some skeletal parts are more easily identifiable as small fragments than others. This goes to the detriment of, e.g., ribs and vertebrae, which often tend to be – relatively – under-represented, and to the profit of elements like radius and tibia where wider surface areas exhibit diagnostic features. Positive deviations from expected values may frequently attain several 100 % if “waste parts” like skull/mandibles or distal limb elements are accumulated. On the other hand, delicate or uncharacteristic elements may be totally or analytically lost, especially in small samples. In the pig, overrepresentations are extreme in the mandible, strong in the skull, the humerus and the pelvis and more moderate in the ribs. Important deficits appear in the vertebrae, the scapula, the femur, the radius/ulna and some smaller elements. The remaining elements are, by and large, represented close to their expected proportions (Fig. 133). While the scarcity of vertebrae is easily explained by their uncharacteristic morphology and delicacy, this does not hold true for the femur and radius/ulna and must be contrasted with the better values for meat-bearing bones like humerus, pelvis and ribs, which are also all of culinary relevance. The over-representation of these latter skeletal parts adds a strong culinary character to the pig bone assemblage; it is certainly not attritional. Especially in the pig, all bones may be actual food relics. Generally, the deviations from the “natural” pattern are not as marked as in many other pig bone assemblages from settlement areas. The over-representation of the mandible is a commonplace in consumption debris and may attain much higher values. Moreover, the weight

Fig. 132. Elderly cattle toothrows. Top: right maxillary FN316 with M2,3; left maxillary FN328 with M3. Bottom: right mandible FN208 with P3–M1, irregular wear.

dairying. The slaughter patterns at Old Scatness indicate a steadier kill-off, although an equally wide range of stages is documented for the Pictish phase, while no animals older than “younger adult” survived in the Viking phase. 9.3.5 Sexing Morphological criteria of the pelvis, namely details of the pubis and the ilium normally used for sexing sheep (Boessneck et al. 1964) and cattle, can be analysed on some remains. Among sheep, seven adult or subadult pelvic fragments, out of 47 remains altogether, exhibited female characteristics, while two specimens are likely to result from males. This proportion is compatible with a herd structure where most rams are slaughtered at a juvenile age. In cattle, the pelvis is only represented by 34 remains. Relevant criteria were found on three specimens: two fragments of the acetabulum area, one with heavy pathological alterations, clearly exhibited female characteristics, while one larger, almost complete specimen, the heaviest bone of the whole material, belonged to a male or castrated animal. Measurements of elements which show a marked metrical sexual dimorphism, like horn cores and metapodials, are not sufficiently available among the material. Some clues could be obtained from well-represented elements, like the astragalus from sheep, if they were compared to a sample of known composition. As regards pigs, skulls and mandibles allow for an easy sexing if the canines or the canine alveolus are preserved. Unfortunately, there are only three fragments which can be sexed: two canines from the upper dentition, one from each sex, and one rostral part of a male mandible.

The data provided by the IPNA – University of Basel on the internet was used as reference: http://ipna.unibas.ch/archbiol/methodik/ index.html 12

99

Sheep, weight representation (%) of skeletal elements

Pig, weight representation (%) of skeletal elements

25

30 25

20

20

15

Skeleton

15

Tingwall

Skeleton Tingwall

10

10

5 Phalanges

Metatarsus

Metacarpus

Tibia

Basipodium

Patella

Radius/Ulna

Pelvis

Femur

Scapula

Humerus

Costae

Sternum

Vertebrae

Os hyoideum

Cranium

Phalanges

Sesamoidea

Metatarsus

Tarsus

Metacarpus

Carpus

Tibia

Fibula

Patella

Radius/Ulna

Pelvis

Femur

Scapula

Humerus

Costae

Sternum

Vertebrae

Os hyoideum

Cranium

0 Mandibula

0

Mandible

5

Fig. 133. Pig, relative weight distribution of skeletal parts from Tingwall, compared to a reference skeleton.

Fig. 134. Sheep, relative weight distribution of skeletal parts from Tingwall, compared to a reference skeleton.

proportions to each other of, e.g., humerus and pelvis, tibia and distal limb elements appear almost in their natural relation. It seems likely that complete animals or carcasses were brought to the site, although the input of selected parts cannot be excluded. The picture for sheep, which is based on a much larger sample, shows some obvious trends (Fig. 134). In certain areas, the two trend lines run in parallel, regularly set-off from each other (lower limbs, metapodials). Marked overrepresentations are documented for the lower legs, metapodials, and the mandible. Also, the proximal long bones and the carpal/tarsal elements lie well above their expected values, and the frequencies of girdle elements and phalanges correspond with them. Deficits are strong for the cranium and the vertebrae, but only moderate for the ribs. This gives the impression that whole carcasses were processed and consumed on the spot, and some “waste parts” were allowed to accumulate. The good representation of long bones and the moderate accumulation of mandibles and metapodials give a strong culinary character to the assemblage. The high number of lower legs (radius and tibia) may indeed, as mentioned above, be due to an “analytical bias” caused by greater identifiability. The deficit of skulls may be a consequence of the prevailing small fragment size, as larger bones may have been deposited elsewhere, while in vertebrae and ribs this deficit appears more like “normal” taphonomic loss. In cattle, deviations are strong for certain elements while being minimal in others (Fig. 135). Positive deviations are particularly present in the skull and mandible, the tarsal bones, the metapodials and the phalanges. All these elements may represent, to some degree, waste parts, likely to accumulate in deposits resulting from primary butchery. In vertebrae, the scapula and the lower legs (radius/ulna and tibia), the representations are close to the expected values. Moderate deficits occur in the humerus and the pelvis, and are more accentuated in the femur and especially the ribs.

While the under-representation of ribs might represent “normal” taphonomic loss, the relative scarcity of some large, meat bearing elements of the hind limb could be caused by use and discard patterns: these elements may have been deposited elsewhere. Also, the general small fragment size should be kept in mind, as it may constitute a disadvantage for the recognition of elements with a low density of diagnostic zones (femur vs. radius and tibia). Nevertheless, the skeletal part distribution again points to the former presence of complete carcasses at the site. The number of horse remains is too small to detect any clear patterning. Teeth or their fragments account for five of the twelve remains. Together with the other finds (e.g. sesamoids), this points at the residuality or the reworking of the equid assemblage. At Old Scatness (Bond et al. 2010), the skeletal part representation was assessed by criteria different from the ones used here. Body parts of cattle seem to be fairly evenly represented in the Pictish phase. The

100

Cattle, weight representation (%) of skeletal elements

Skeleton

Sesamoid

Phalanges

Metatarsus

Metacarpus

Tarsus

Carpus

Tibia

Radius/Ulna

Femur

Patella

Pelvis

Scapula

Humerus

Sternum

Costae

Vertebrae

Os hyoideum

Cranium

Tingwall

Mandible

18 16 14 12 10 8 6 4 2 0

Fig. 135. Cattle, relative weight distribution of skeletal parts from Tingwall, compared to a reference skeleton.

Taxa Bos Ovis Sus cattle-size sheep/pig-size Aves

cut 99 104 23 8 3 2

% NISP 9.1 8.3 7.3 4.5 2.7 3.6

chop 25 17 6 1

% NISP 2.3 1.4 1.9 0.6

1

1.8

cut & chop 4 1 3

% NISP 0.4 0.1 1.0

total 128 122 32 9 3 3

% NISP 11.8 9.7 10.2 5.1 2.7 5.4

Table 13. Butchery marks on main domesticates.

authors conclude that from all three domestic mammals “… probably whole, live, animals of slaughtering age were brought to the site, if indeed they were not bred there.” 9.4.2 Butchery marks Anthropogenic tool marks were recorded by mark type and anatomical position. In the butchering process at Tingwall, metal blades of differing width and size were used. Chop marks, resulting from forceful blows, usually carried out with a heavy tool, can be opposed to cut marks, which are generated by pressure, using blades of all kinds. Normally, chop marks are associated with tools like choppers or axes, and cut marks with knives, but it is basically the way the blade is used that defines the mark type. The positions on the bones were documented with a short verbal description (e.g. “transverse cuts on ventral area of ilium”). Butchery marks were found on the main domesticates including the cattle- and sheep/pig-size categories, and on birds. The overall percentages of butchered bones can be found in Table 13. For the main domesticates, the percentages vary from 9.7 % in sheep to 10.2 %

in pig and 11.8 % in cattle. Although butchery marks appear to be a little more frequent at Tingwall, this data is comparable with the Pictish and Viking phases at Old Scatness, although there it is always cattle which exhibit the lowest frequencies of butchered bones, while pig takes the first place. At the Late Norse phase at Old Scatness, percentages were considerably higher, with over 20 % knife cuts in cattle and 30 % in pigs. Percentages between 5 % and 10 % are labelled as low frequencies by the authors of the Old Scatness report. Of course this must be considered within the framework of the site and may be related to other factors like surface preservation and diagnostic criteria. Regarding the relation of cut marks to chop marks, the situation at Tingwall is again similar to the Pictish and Viking phases at Old Scatness: cut marks are generally more frequent than chops, and chop marks are comparatively rare in sheep. In Table 14 and Fig. 136–137, the relative and absolute abundances of butchery marks on the different skeletal parts are given. In cattle, marks were observed on 128 bone specimens of all element groups present, with the exception of the patella (Fig. 138). Apart from the hyoid bones, where

Pig, % of remains with cut- and chop-marks

Sheep, % of remains with cut- and chop-marks 35%

35% 30%

30%

None

25%

Both

None Both

Chop

Chop

Fig. 136. Sheep, percentages of skeletal elements with cut- and chop-marks.

Fig. 137. Pig, percentages of skeletal elements with cut- and chop-marks. 101

Phalanges

Metatarsus

Metacarpus

Basipodium

Tibia

Fibula

Femur

Radius/Ulna

Pelvis

Scapula

Humerus

Cranium

Phalanges

Metatarsus

Metacarpus

Tibia

Basipodium

Patella

Radius/Ulna

Pelvis

Femur

Humerus

Costae

0%

Scapula

0% Vertebrae

5%

Os hyoideum

5%

Cranium

10%

Mandible

10%

Costae

15%

Vertebrae

15%

Cut

20%

Cut

20%

Mandibula

25%

Bos

Table 14. Butchery marks on different skeletal parts.

Cranium

Chop

Cut

None

Total

3

4

170

177

3

146

149

Mandible Os hyoideum

Both

1

2

3

135

169

22

97

121

3

26

31

1

4

23

28

1

5

28

34

1

38

39

4

4

Vertebrae

12

21

Costae

2

Scapula

2

Humerus Pelvis Femur

1

Patella Radius/Ulna

4

60

64

Tibia

4

41

45

Basipodium

10

44

54

Metacarpus

2

33

35

Metatarsus

3

5

1

43

52

Phalanges

1

10

2

60

73

Chop

Cut

Both

None

Total

Sheep Cranium

3

105

108

Mandible

4

130

134

Os hyoideum

1

2

3 130

161

204

5

16

Costae

7

36 1

36

37

1

12

68

81

4

43

47

3

64

68

3

3

Scapula Humerus Pelvis Femur

1

1

108

Vertebrae

Patella Radius/Ulna

6

94

100

Tibia

3

103

106

1

9

43

53

1

57

58

Metatarsus

1

1

62

64

Phalanges

1

4

51

56

Chop

Cut

None

Total

46

46

Basipodium Metacarpus

Pig

Both

Cranium Mandibula

35

35

Vertebrae

4

3

1

35

43

Costae

1

12

1

74

88

Scapula Humerus

3

Pelvis

3

Femur Radius/Ulna Tibia

1

Fibula Basipodium

1

Metacarpus Metatarsus

1

Phalanges

102

1

5

5

16

19

9

13

2

2

7

7

11

12

5

5

6

7

10

10

8

9

12

12

35% 30%

None

25%

Both Cut

20%

Chop

15% 10% 5%

Phalanges

Metatarsus

Metacarpus

Basipodium

Tibia

Patella

Radius/Ulna

Pelvis

Femur

Humerus

Costae

Scapula

Vertebrae

Mandible

Os hyoideum

Cranium

0%

Fig. 139. Thoracic vertebrae of cattle, neural arches and spinous processes with chop marks, dorsal view; top: FN128; bottom: FN293.

Fig. 138. Cattle, percentages of skeletal elements with cut- and chop-marks.

one out of three specimens showed a cut, the highest frequencies (15–20 % of NISP of the respective element) of butchered bones were found in the axial skeleton, the humerus, the girdle elements, the basipodium, the metatarsus and the phalanges. Moderate rates (5–10 % of NISP) are present in the lower legs (radius/ulna and tibia) and the metacarpus. The skull elements and the femur exhibit the lowest frequencies (