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HJSJS.TOCEME GBQLOGY OF OTA *
m Jack Bennett Grahaia
A d is s e r ta tio n subm itted in p a r tia l fu lfillm e n t of th e requirem ents fo r th e degree of Doctor of Philosophy, in the Department of Geology, in the Graduate College of th e S tate U niversity o f Iowa ttqr* 191)2 This re p o rt, a f te r re v is io n , w ill be published by the Iowa Geological Survey under the j o in t authorship of George F# Kay end Jack B* Graham since th e re has been clo se cooperation in f ie ld stu d ies and in the prepar a tio n o f the manuscript#
ProQuest Number: 10598677
All rights reserved INFORMATION TO ALL USERS The quality o f this rep ro d u ctio n is d e p e n d e n t u p o n th e quality o f th e c o p y subm itted. In th e unlikely e v e n t th a t th e au th o r did n o t sen d a c o m p le te m anuscript a n d th e re a re missing p a g e s , th e s e will b e n o te d . Also, if m aterial h a d to b e rem o v e d , a n o te will in d icate th e d eletion.
uest. P roQ uest 10598677 Published by ProQ uest LLC (2017). C opyright of th e Dissertation is held by th e Author. All rights reserved. This work is p ro te c te d a g a in st unauthorized copying u n d er Title 17, United S tates C o d e Microform Edition © ProQ uest LLC. ProQ uest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106 - 1346
ii
TABLE OF 0OHMJTS
Pag© w tro d dctig s
chapter
i.
the cehtraliah epoch
( s e r i e s )*
the il l ih o im j
GLACIAL AGE (STAGE) ..........................
♦.* .♦*•.**.
1
D iscrim ination of the Illin o la n d r i f t ...............
2
D istrib u tio n of the I llia o ia n d r i f t in Iowa . . . . . . . . . . . . . .
3
Origin of the d r i f t
5
. . . . . . . . . . . . . . . . . . . . .............
Changes in the d r i f t ...............
5
Typical sections of the 111inoian d r i f t . . . . . . . . . . . . . . . . . .
8
Exposures in Scott County
..........................
Exposures in Muscatine C ounty Exposures in Louisa County
. . . . ...................
8
10
................................
Exposures in Dee Moines end Henry Counties . . . . . . . . . . Sections in Lee County
13 II4
.................
16
D escriptions of the d r i f t phases . . . . . . . . . . . . . . . . . . . . . . . . .
19
The Illin o la n gumboil! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19
Oxidised and leached Illin o la n t i l l
22
Oxidised and unleashed Illin o la n t i l l
.........
Unoxidized and unleached Illin o la n t i l l • » • » « . . . . . . » •
26 28
Thickness o f th e Illin o la n d r i f t *.•»•».«*«•••....................
30
CHAPTER I I . THE CEHTIALIAH EPOCH (SERIES)* THE SAHGAM IHTERGLACIAL AGE (STAGE)............................................ The Sangamon record D escriptions of Sangamon featu res
33
................... ...................
Illin o la n gumbotil and re la te d weathered eones ...............
33
$b 3^
iii
Pag® .........* . . . . * * ............
Sangamon sands and gravels
Weathered Illin o ia n upland gravels .............. .. Late Sangamon loess
35 55
........ •
3&
Sangamon peat deposits and s o ils . . . . . . . . . . . . . . . . . . . .
J8
........ ........... ..
Lake Calvin
bb I.i9
Sangamon erosion . . . . . . . . . . . . . . . ........... Comparative d issection of the Illin o la n and Kansan d r ift plains . . . . . . . . . ........ ..
b9
Record of l i f e in the Sangamon . . . . . . . . . . . . . . . . . . . . . . . . . . .
51
The Loveland formation
........ .....................................................
55
History of investigations of th® Loveland formation .
55
Loveland loess
59
......... ...........
Sections of Loveland loess
. ..#
Laboratory studies of the Loveland loess Mechanical analyses
.................
Mineral analyses . . . . . . . . . . . . . . . . . . . . . . . . . . Loveland sands and gravels
.........*................
59 6b 6b 6b 66
Volcanic ash in the Loveland formation . . . . . . . . . . . . . .
75
CHAPTER III* THE ELDQRAN EPOCH (SERIES)s THE WISCQISIH GLACIAL AGE (STAGE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............ **
79
The c la s sific a tio n of the Wisconsin age (stage) . . . . . . . . . .
79
The Iowan Glacial Subage (Substage)
...........
83
Discrimination of the Iowan d r ift •*#•»«*.**••«.......... *****
83
D istribution of the Iowan d r ift In Iowa
97
Origin of the Iowan d r i f t Changes in the Iowan d r ift
.........
102 10b
iv
Page ty p ic a l sections of th e Iowan d r i f t
...........
Iowan d r i f t in northeastern
Iowa. . . . . . . . . . . . . . . . . . . . . 105
Iowan d r i f t in northw estern
Iowa
D escriptions of th© d r i f t phases Iowan boulders
118
. . . . . . . . . . . . . . . . 3. . . . . . . . . 131 .........
131
the Iowan pebble band Oxidised and leeched Iowan t i l l
135 ...........
II 4O
Oxidised and unleached Iowan t i l l . . . . . . . . . . . . . . . . . . . .
II4I4
TJnoxidised and unleashed Iowan t i l l . . . . . . . . . . . . . . . . . .
Iit5
Iowan gravels
Ik?
the Iowan upland gravel
.........
the Iowan te rra c e gravel Thickness of th e Iowan d r i f t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . the Peorian In tra g la c ia l Subage (Substage) . . . . . C la ssific a tio n of th© Peorian intraglaoi& l subage (SUbStag©) ............. the Peorian loess D istrib u tio n and topographic expression of th© Peorian lo ess in Iowa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Loess mantled ©rosional topography
ll*7 1$1 157 l6 l 161
16? ? p* • Li^
1?0
General c h a ra c te ristio s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
,f .
The Cedar and Jackson areas . . . . . . . . . . . . . . . .
C h a ra c te ristic s of the Peorian loess
q , ^
167 * ^
168
Typical sections of the Peorian loess in low® . . . . . . . . . . . . .
t 6 f*' Cef*
I 65
The Crawford area
Loess depositional topography . . . . . . . . . . . . . . . . . . .
J
105
^ ^
171 % 172 179 179
if
}oft"
Pttgo
j
lle e h in ic a l a n aly se s » • ♦ . . . ..........
180
Mineral analyses
183
...............
C hem oal a n a ly se s
181*
F o ssils of tb s Peorian loess . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
187
V e rte b ra te s
J
Inv© :*tebrates
CfLc' ^
187 ................
%
191
Depth of leaching in the Peorian lo ess . . . . . . . . . . . . . . . . . . . . Thielpess of the Peorian lo ess in Iowa . . . . . . . . . . . . . . . . . . . .
199 200
The Mankato C laoial Subage (Substage)
203
D iscrim ination of the Mankato d r i f t
205 •
Origin of the d r i f t
, *'
f*
Vf t
^
207
**
208
•»
Changes in th e d r i f t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
209
"
Typical sections of th© Mankato d r i f t . . . . . . . . . . . . . . . . . . . . .
211
"
Mankato t i l l over lo ess and pre-Iowan t i l l Mankato t i l l over Peorian loess
.........
Exposures showing only Mankato t i l l or gravel • « . . . • . •
r
197 ) 6p{.
Comparison of the Peorian loess with the Loveland loess . . . . . . . .
D istrib u tio n of th® Mankato d r i f t in Iowa
J O p ^ c ^ -
211
lt> p* *
217 219
*'
22l*
V ft
Oxidised and leached Mankato t i l l
22i*
>* ft*
Oxidised and unleached Mankato t i l l
225
"
Unoxidized and unleaohed Mankato t i l l
227
11
D escriptions of th© d r i f t phase®
228
%^
^
The Mankato upland gravel
228
10 pf
ff ':l
The Mankato terrace gravel
233
The Mankato gravels
0
£
vi
Fag© Th© Mankato iaoraini© eompleat Thickness of th© Mankato d r i f t CHAPTER IV,
238
.........
2l$
THE HECIIT OTMUCIAL A® (STAGE) OF TM
m&mm m m &
............ . .............. *****
(e p o c h )
21+6 10 p*
Th© record of the Reeent
2h7
^ ft- cy a ^
D escriptions of Recent fea tu res ».«««...........•*»»*»«•............ *
2i*8
M
2i|8 ( O ^ t ^ c ^ ^
Leached Mankato d r i f t Peat on th© Mankato d r i f t Duration of th© Reoent
........ •#•»*•*•*••••••*•••*•
2i$
M
252 % y l c^ f 3 ^
v ii
LOT OF 1XJWJSIRATI08B Figures I*
Page
Map showing th© surface d is trib u tio n of th© d r i f t sheet® and other g la c ia l features o f Icwa ...............
2a
top of Iowa showing th© extent of IIIIn o ia n g la c ia tio n in th© State .........
Iia
}•
Diagram of a complete normal sectio n of Illin o la n t i l l
8a
li.
Exposure showing dark s o il, Peorian lo e s s , and Loveland loess* Brick and f i l e P lant, M ediapolis, Des Moines county**
ll*&
Graphs showing mechanical analyses of Illin o la n gumbotil from s ix d iffe re n t l o c a l i t i e s
2 Q&
Graph® showing average mechanical analyses o f th© several t i l l s in Iowa *.............
21a
Graphs showing average shape analyses of I llin o la n gumbot i l and uaoxidised and ualeached 111inoian t i l l ••».•••**••«
22 a
Map of eastern Iowa showing locatio n s of exposures of 11lin o i an and Kansan gumbotils
2^a
8.
5* 6.
7* 8*
9* 10*
Graphs showing (a) , mechanical an aly sis and (b), 1ith o logio analysis of Illin o ia a upland gravel .
.
36 a
Diagraia showing the stra tig ra p h ic re la tio n sh ip s of Love land loess in ©astern Iowa
37©
Graph showing pollen percentages in a Sangamon peat bed* (Geo* H. Lane)
ijOa
12.
Sketch map of th e Lake Calvin area
k5&
13*
Diagram showing the Loveland 1o©sb rela tio n sh ip s e a s t ward from th© type area in w estern Iowa
58a
Layer of concretions in th© Loveland loess exposed in th© v a lle y b lu ffs near Council B luffs
59a
Section showing Loveland lo e s s, Iowan t i l l and Peorian loess* O’Brien county •*««****••*.•«**•**••**»•»»•*•».«*»*•
6 l&
Section in Fayette county, showing Loveland loess below Iowan t i l l .........
62©
11.
111*
15* 16.
...................
v iii
F igures
i?* 13* 19*
Peg®
Hep showing lo cations of Loveland loess samples used in compiling average analyses
6^a
Graph showing mechanical analysis of average of 35 Samp le s of Loveland loess
61ib
Diagram illu s tr a tin g s im ila rity of minor m ineral percent ages in Kansan t i l l and Loveland loess •••. *••**»••*•••. *••
66a
20.
Hap showing locatio n s of Loveland sand and gravel ex posures in Iowa
21.
Map showing locatio n s of *und i f fe re n t iated te rra c e gravel* exposures in Iowa •«**».**•*#*»*#*•#*#••*..•*»*«*•*
70a
Graphs showingmechanical analyses of Loveland grave 1* the numbers o f th is fig u re correspond w ith those of figure 23 . . . I . * * . . . . . , * . * . . * * . . * * * . * * . * . . * * . . . . . . . , * . * ......... . . . . . .
71a
Graphs showing lith o lo g y of pebbles between 16 and 32 m illim eters in diameter* The numbers of those analyses correspond to those of figure 22 •.*«*»••*•#*••«•#••*••••••
71b
(a) Volcanic ash in the Loveland form ation. H arrison county, (b) Graph showing mechanical an aly sis of the ash. (A. C. T ester)
77«
Map of Iowa showing th e extent o f Iowan g la c ia tio n in the s ta te .........
97a
22*
23*
2l*.
25* 26.
Hap of Iowa showing by p attern s the main areas of d is tin c tiv e topographic development In the s ta te »*••«••«*•*..
100a
27*
Map of Iowa showing by diagram the depths o f leaching of calcium carbonate in m aterials w ithin th e Iowan and Mankato d r i f t areas of Iowa ........................................................ 105®
28.
Iowan d r i f t overlying d is tin c tiv e Buchanan gravels near D oris, Buchanan county
109«
Map of Iowa showing th© locatio n s o f large g ra n itic boulders in and adjacent to the Iowan d r i f t area. (Modified from Aldan and Leighton, 1915) *•.*#***•**•**•***
131®
29*
30.
Field of Iowan boulders south of B a ssett, Chickasaw county ........................................................ 132a
31*
Large Iowan boulders In Buchanan county . . . . . . . . . . . I . . . . * * *
I 3I4&
ix
Figures 32.
Page
Iowan boulder in Grundy county measuring th irty -tw o by tw enty-eight fe e t on the ground w ith an exposed height of ten fe e t
135*
Pebble band with Icwan t i l l below and Peorian loess ............. above, Fremont township, Cedar county
136a
Pebble band on Iowan t i l l Ju st west of Denver Junction, ............................... Bremer county
137*
35«
Map of Iowa shewing the locations of Iowan upland gravels*
litf*
36 #
Graph® showing the mechanical analyses of Iowan upland gravels . . •.#«•#*«•#••»••••• . . . . . . . . . . . . . . ............... * . . .
lijBft
Graphs shewing the llth o lo g ic a l analyses o f Iowan up land gravels w ithin th e six teen to th irty -tw o m i l l i meter else range ....... ......... . . . . . . . . . . . . . .
li*8b
Map of low® showing the locations of Iowan te rra c e gravel exposures . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...........
151*
Terrace gravel of Iowan age near Iowa C ity, Johnson county .............
152ft
Graphs showing mechanical analyses of Iowan te rra c e gravel................................ . .*****....................*.............
153*
Graphs showing the lith o lo g ic a l analyses of Iowan t e r race gravel w ithin th© 16 to 32 mm. in diameter size range
153b
Divide out between Aspinwall and M anilla, Crawford county, showing about tw enty-five fe e t of Peorian loess overlying Kansan d r i f t .•«***••*#•«***•*••••••*..•*»
169®
Looking north along loess b lu ffs from top of ridge south of Piagah, Harrison county
169b
Cut showing ninety fe e t of Peorian lo e ss, near Mis souri V alley, Harrison county *#••«•••••.**•*«••*••••*••*•
171ft
Airplane view of north-south trending loess ridges on the Iowa side of the Missouri r iv e r v a lle y . ( Photo by De® Moines E egister-T ribune) .........
172e
Loess h i l l bordering the Iowan d r i f t p la in near f o r th L iberty, Johnson county. A fifty -tw o foot loess sec tio n was obtained here
173*
33 .
3b#
37*
38 #
39* I4O0 ill.
1*2.
1*3* i&* 1*5»
1*6.
X
Figure® 1*7*
1*8* 1*9#
50* 51. 52. 53* 5!*•
55* 56* 57*
58* 59* 60* 61*
Pag®
Graph showing a se rie s of medhanieal analyse® of a lo ess se ctio n near Mortb L iberty, Johnson county# Samples taken two fe e t ap art v e r tic a lly «•........... . . . . . . . . . .
17l*a
Topographic map of the Worth L iberty area showing the lo catio n of the fifty -tw o foot loess sectio n . . . . . . . . . . . . .
1714b
View in th© Gaulocher clay p i t , Iowa C ity, Johnson county, showing two phases of lo ess and e ffe c t of p lan t roots in oxidation and deoxidation *****.....................
175®
Peorian loess o verlain by Mankato d r i f t , ju s t west of Panora, Guthrie county
177®
V e rtic al w alls in a Peorian loess mat near Magnolia, Harrison county ............ . . . . . . . . . . . ..........
180a
Map of Iowa showing traverse® followed in c o lle c tin g Peorian loess samples used in laboratory analyses . . . . . . . .
181a
Graph showing the se rie s of mechanical analyses of loess sample® co llected between Sioux City and Spencer •••
181b
Graph showing the eerie® of mechanical analyses of loess samples collected between Sioux C ity and Sac City ...............
181c
Graph showing th© s e rie s of mechanical analyse© of loess samples collected between Donne Is on and Sidney . . . . .
18ld
Graph showing th© se rie s of mechanical analyses of loess samples collected between Tam© and Iowa F a lls •••*•«
181®
Graph showing the s e rie s of mechanical analyses of loess samples collected between M issouri V alley and Iowa C i t y *********.........**............
181f
Graphs showing meohaaical analyses of Peorian loos® collected in northeastern Iowa «• • • *. • • • *• • • • • • • • • • • • • *• «»
182©
Graphs showing mechanical analyses of Peorian loess co llected in n ortheastern Iowa • , • • • . • • • . • • • • . • • « • • * • * * • * *
162b
Graph showing th© average mechanical an aly sis fo r loes® samples co llected throughout Iowa.. . . . . . . . . . . . . . . . . . . . . . . .
182e
M ineralogieal analyses of various P leistocene material® of Iowa*** ................................................ 183®
xi
Figures 62#
Page
Graphs i ll u s t r a ti n g the c o rre la tio n of heavy m ineral percentages of Peorian lo e ss, 1 m m t i l l , Loveland loess and Kansan t i l l , of Iowa
183b
Graphs showing the ohemic&l analyses of leached Peori an lOeSS .........
186ft
6k*
T e rre s tria l gastropods of th© Peorian loess of Iowa ******
192a
65*
Graph showing the 'Vertl'eal d is trib u tio n of f o s s ils id e n tifie d in the loess section near lo r th L iberty, Johnson county. (Dr. Cornelia Cameron)
19lta
Map of Iowa showing re la tiv e thickness of Peorian loess by degree of shading •«***.•*.•»*«••••**••*••*••••••
200a
63 *
66 * 6?*
Map o f Iowa showing by contours the thickness of th© ............................................... . . . . . . . . . . . 200b Peorian loess
68.
Map of Iowa showing locations of Loveland and Peorian loess samples co llected for laboratory analyses . . . . . . . . . .
201 a
Graphs showing the mechanical and heavy mineralogies! analyses of Loveland and Peorian loesses *.........
201b
Stream on the Mankato d r i f t illu s tr a tin g th e immature stage of erosion of the d r i f t . Palo Alto county . . . . . . . . .
205a
Sketch map showing peat, muck and lake areas on th© Man kato d r i f t p la in j Wright county . . . . . . . . . . . . . . . . . . . . . . . . . .
207a
72*
Map of Iowa showing the extent of Mankato g la c ia tio n *****
207b
73*
Lithologieal analysis of leached and unleashed Mankato till ........ **********................
225a
Map of Iowa showing locations of Mankato upland gravel deposits •••*•••••••••••••»• *• • *• • • • • • • • • • • • *»**• «*• • • • *• •
229 a
Graphs showing mechanical analyses of Mankato upland gravels •• ••• •»*• »• •»•*•. . ••**• ••• *• •*••. • •*«• ••• •*••*•• «*
229b
Graphs showing lith o lo g ie a l analyses of Mankato upland gravels w ithin th© sixteen to th irty -tw o m illim eter in diam eter sla© range A,***.***#****.**..**...**#*.*••#••*••
229 ©
Map of Iowa showing locations of Mankato terrao© gravel deposits .........
23k*
69* 70* 71*
7k • 75* 76*
17*
x ii
Figure® 78. 79*
Page
Graphs showing mechanical analyses of Mankato te rra c e gravels .............
255*
Graph® showing lith o lo g ie a l analyses of Mankato te r* race gravels w ithin the six tee n to th irty -tw o m illi meter in diam eter sis© range
235b
80*
Mankato morainio topography I Wright county
81,
G lacial map o f Iowa w ith the major Mankato moraines Indicated by number .........
214.0a
Fie# of Gcheyedan Mound, a Mankato morainic featu re in Osceola county *•, •»•••. ••**,•*»«*#••••••»•••••*•*•»••«
2 l40b
Map of the Mankato d r i f t area in Iowa showing locations of peat deposits ...............
251®
Diagrammatic rep resen tatio n of the depth of leaching o f upland gravels in th© various d r i f t sheets of Iowa
253®
Diagram illu s tr a tin g minimum estim ate of th e duration of th e EXdoran epoch in Xowaf based on depth of leaching . . «•
2$*a
Diagram i llu s tr a tin g the minimum estim ate of th© duration of the Pleistocene period in Iowa ............ . . . . . . . . . . . .
253®
82. 83 *
8l|* 85 ,
86.
............
238a
x iii
x m sm a siV K f m XLlWOim AID POST-IULBTOIM PLBIS3?OCm GEOLOGY OF IOWA In th© year 1928, th® P re -Illin o la n Pleistocene Geology of low* was published by Kay and Apf®l in Volume XXXIV of th© rep o rts of the Iowa Geological Survey.
Exclusive of the Preface, Introduction,
and Concluding Statem ents, th is rep o rt contained the following chap ters* Chapter I . The Bedrock Surface of Iowa Chapter II* Topography and Drainage of Iowa Chapter III* H istory of th© In vestigations and C lassIfio atio n s of the Pleistocene Geology o f Iowa Chapter IV# The Rebrassksn G lacial Stag© Chapter V. Th© Aftonian In te rg la c ia l Stage Chapter VI* Th© Kansan G lacial Stag© Chapter V II. Th© Yarmouth laterg l& clal Stage When th is Pre-XIlinGian p a rt of the Pleistocene geology of Iowa was pre pared, I t was th© hop© of th© senior author th a t a t so®© l a t e r time an equally eorapreheneiv© rep o rt might be prepared on th a t p a rt of th© P le is tocene of Iowa not discussed in d e ta il in the P re -Illin o ia a re p o rt. Such a report has now been completed and is being presented f o r publication* I t is e n title d The I llin o la n and P o s t-Illin o la n Pleistocene Geology of Iowa.
In th© preparation of th is rep o rt there has been no h e sita tio n
about using many fa c ts which have appeared in former papers dealing w ith the Pleistocene of th© state*
The rep o rt wi l l make av ailable in on© place
th© present day evidence and in te rp re ta tio n s o f th© IlXinoian and Wis consin g la c ia l stages and the Sangamon and Recent in te rg la c ia l stages of the Pleistocene of Iowa*
x iv
When the report on the Pre-Tllinoisn Pleistocene geology of Iowa wee published* It seemed wise to se t aside fiv e hundred unbound copies with the purpose in mind that a fter th® Illin o ia n end P o st-Illinolan Pleistocene geology report had been published, the two reports, five hundred copies of each report, should be bound together and design aaied the Pleistocene Geology of Iowa*
Part I would be the P ro-IIlin oi
an Pleistocene Geology of Iowa and part I I , the Iilin oian and Post-X llinoian Pleistocene Geology of Iowa*
This plan w ill be followed*
It
Is Intended also to include in th is Pleistocene Geology of Iowa a bib liography o f the Pleistocene of Iowa and adjacent sta te s of the Missis sippi Valley, Since the publication of the P re-Illinolan report, some sig nifican t papers have been published by the senior author*
Chief among
these are th© following* C lassification and Mratie»r of the Pleistocene Period* B u ll,, CJecl* Sgq* of America* Vol. XLII, pp* ^5-1*66, 1931* Origin of the Pebble Band on Iowan T ill* dour* of Geol•, Vol* XXXIX, Mo* J4, May - June, 1931* (With M* M, Leighton) Th© Eldoran Epoch of th© Pleistocene Periods Bull*, Geol. Soc* of America, Vol* XLIV, pp. 669-673, 1933* Pleistocene History and Early Man in America* Bull*, Geol. See. of America, Vol* L, pp. l& ^hSh, 1939. The c la ssific a tio n s of th© Pleistocene of th© M ississippi Val ley and of Iowa are recognised by the Iowa Geological Survey as follows*
XV
C lassification of Pleistocene geology in the M ississippi Talley Bpoohs (se r ie s)
Period (system)
Ages (stages)
Substages
Recent Eldoran Wisconsin Pleistocene
Mankato Cary Tazewell Iowan
or Centralian
Sangamon Illin olan
Ottianwan
Yarmouth Kansan
Grandian
Aftonian Sebraskan
Glacial
|
C lassification of the Pleistocene geology of Iowa Period (System)
Epochs(Series)
Ages(Staged
Substages
Recent Bldoran Wisconsin Pleistocene or
Centralian
Sangamon Illin o la n
Ottumwan
Yarmouth Kansan
Grandia©
Aft onion Webraskan
Mankato Peorian Iowan
Glacial
The chapters of th© report on th© Illin olan and po st-Illin o la n Pleistocene Geology of Iowa are as follows*
xv i
Chapter I .
The Illin o la n G lacial Stag® (Age) of the Centrali&n Series(Bpoeh) Chapter II* The Sangamon In te rg la o la l Stage (Age) of th© Cen t r a l Ian S eries (Epoch) Chapter III* Th© Wisconsin G lacial Stag© (Age) of th© Eldorsn S eries (Epoch) Th® Iowan G lacial Subst&g© The Peorian In tra g la c ia l Substag® The Mankato G lacial Substage Chapter IV* The Recent In te rg la c ia l Stage (Age) o f th© Eldoran Series (Bpooh) Th® authors wish to acknowledge th e i r o b lig atio n to th e la te Dr* James B* Lees* A ssistant S ta te Geologist of Iowa from 1906 u n til 19$in also to express t h e i r thanks to Br* E* T. Apfel, Br* Paul Miller* Dr. l a r i T* Miner, Dr. R* Edmund* and Dr* Cornelia C* Cameron*
Results
of t h e ir stu d ies have been drawn upon fre e ly and used in various ways in t h is report*
Chapter I TEE CMTHALIM EPOCH (SERIES) THE ILLIBOIAH GLACIAL MM (STAGE) Discrimination of th© Illin olan d r ift Distribution of th© lllin o ia n d r ift in Iowa Origin of th© d r ift Changes in th© d r ift Typical sections of th® Illin olan d r ift Descriptions of th© d r ift phases Th© Illin olan gumhotil Oxidised and leached Illinolan t i l l Oxidised and unleashed lllin o ia n t i l l Cnoxidised and unleashed lllin o ia n t i l l Thickness of the Illin olan d r ift 1
The Centralism ©pooh (se r ie s)
Includes the lllin o ia n glaolal
r
■ ~~ Bay* G* F*, C lassification and Duration of the Pleistocene Period t Bull* Geol* Soe* o f America, Vol. 1*2, pp. 1931* age (stage) and the Sangamon in terglacial ag© (sta g e).
The Illia o ia a
glacial age followed th© Yarmouth interglaoial ag© and is the third of th© g la cia l ages in th© Pleistocene Period.
Th© glacial d r ift of th©
lllin o ia n ag© was f i f s t distinguished by Levereth.
It was described by 2 him in 1699 i» his monograph on th© I llin o is Glacial Lob© and was named ---------
2
Leverett, Frank, Th® I llin o is Glacial bobet E» 8. GeeX* Survey, Mon. 38, 1699* from th© sta te of Illin o is* where h® had mad® hi© most extensive studies of th© d r ift sheet.
It was f ir s t named th© I llin o is g la cia l lobe, but
th® name has been changed by la ter usage to lllin o ia n to agree with the names of other stages.
Th© lllin o ia n was th® la s t d r ift sheet to be d if -
ferentiated in th© M ississippi Valley although the Hebraskaa did not re ceive I ts present name u n til ten years la ter, Is 1909, when Shimek gave
-2-
th ftt name to th e d r i f t sheet th a t had previously gone by th© nondescript names of Sub-Aft onian or Pre-Kanean.
The g la c ia l map of Iowa, fig u re 1,
shows the d r i f t sheets and other g la c ia l featu res of the state* The lllin o ia n ice-sh eet came in to Iowa from th e Labradorean center*
The d r i f t l e f t by th is ic e -sh e et is exposed widely in I l l i n o i s ,
Indiana, and Ohio* Discrim ination of th e Illin o la n D rift For the most p a rt the lllin o ia n d r i f t is sim ila r to th e older d r i f ts on whleh i t lies*
I t is ty p ic a lly a dark gray clay w ith unassort
ed pebbles of varied kinds and sizes* ones are
uncommon.
Boulders are p resen t, but large
However, one g ran ite e r r a tic was observed whose d i
mensions above ground were tw enty-four by twenty-on© by te n feet*
In
places the lllin o ia n t i l l seems to b© ra th e r lig h te r in color than are /TansQ/7 th e ty p ic a l and Nebraskan t i l l s , and a t other places i t is qu ite sandy* This, however, is & featu re th a t is shared by a l l the d r i f t sheets*
Like
the other d r i f t sheets a ls o , th is on© includes g rea t pockets or lenses of gravels th a t e ith e r are surrounded by t i l l or l i e on i t s surface*
The
boat example of these gravels is found in th e v a lle y of lied Creek in the northeastern o u ts k irts of Muscatine*
That the lllin o ia n d r i f t sheet has
passed through e s s e n tia lly th e same succession of ©vents as had the old er sheets before i t is indicated by th e presence over i t s upper surface of gumbotil as much lik e the Kansan and Nebraskan gumbotils as those t i l l s are lik e th e lllin o ia n t i l l *
This d ifferen ce is to be noted, however,
th a t whereas th© Nebraskan and Kansan gumbotils average above eig h t and about eleven f e e t in thickness resp ectiv ely , th© average maximum th ic k ness of th e lllin o ia n gumbotil is le s s than fiv e f e e t.
I t is evident
th a t conditions favorable fo r gumbotil formation were not so long con-
DRIFT SHEETS WISCONSIN
Mariuto
i lonn j
1— J
23
UJN01AN
E 3
KANSAN
E 3
hebraskan
ES23
MORAINES
£3
LAKE CALVIN B PUEIST PEAT STRIAE
MAP OF IOWA
Figure I# Map shewing the surface d is trib u tio n o f the d r i f t sheets tad eth e r g la c ia l fe a tu re s o f Iowa.
♦
-3-
tinued a f te r th s uncovering of th# lllliio ifm drift* shoot as a f te r th© formation o f th© older ones.
Such gravels as lay a t o r near th© surface
of th e d r i f t were strongly leached u n til t h e ir soluble c o n stitu en ts were removed e n tir e ly from the upper parts* Normally, the lllin o ia n d r i f t re s ts on Kansan gumbotil o r, where th is was eroded before the oncoming of the lllin o ia n g la c ie r, on Kansan t i l l in various stages of oxidation and leaching or on Kansan gravels# Kansan d r i f t caps th© Nebraskan d r i f t everywhere w ithin the area in Iowa covered by th e lllin o ia n d r i f t sh e et, and i t is not known th a t the Kansan was anywhere e n tire ly eroded from above the Nebraskan, allowing th e 1111* noian d r i f t to r e s t d ir e c tly on Nebraskan# Above th e lllin o ia n m ateria ls may be found la te Sangamon or Loveland lo ess, s o il o r p eat, Peorian loess and. wind-blown sand#
Perhaps
Iowan drifts o v erlies lllin o ia n in th© area of t h e i r co n tact, b u t th is 3ms not been seen m account o f th© thickness o f the loess and sand in th is region#
The loess and sand m aterials have been seen on lllin o ia n gumbo
i sim ilar phases are found in contact* I t unleached lllin o ia n t i l l l i e s d ire c tly on unleashed Kansan t i l l th e two might not be distinguishable# I t is much more common, however, to find yellow oxidised t i l l , e ith e r leached or unleached, on Kansan gumbotil#
In th is case the upper t i l l
may be c alle d lllin o ia n w ith assurance; and where any other unlike phases l ie in co n tact, t h e i r ages may be known w ith equal c e rta in ty . D istrib u tio n of the lllin o ia n D rift in Iowa Th© lllin o ia n g la c ie r was near i t s maximum extent when i t reached
M ississippi r iv e r on i t s long journey from th© Labradorean cen ter of d is persion*
Therefore, i t pushed over in to lewa fo r only a few m iles; and
the sheet of d r i f t th a t i t l e f t has a width west o f th e M ississippi rang ing from about four miles a t Sfiusoatine to about twenty m iles a sh o rt d is tance north of B urlington.
The northern lim it o f th© d r i f t is probably
somewhere near the mouth of the Wapsipinicon riv e r and i t s southern ex trem ity in Iowa is ju s t south of Port Madison.
Some p a rts of th e margin
grade indefinably into the Kansan d r i f t p la in ; elsewhere, as a t West P oin t, a d is tin c t moraine marks th© boundary between th e two plains} and between Stockton, Moscow, and Columbus Junction, a low a re a, the s i t e of g la c ia l Lake Calvin, follows the edge o f th# lllin o ia n g la c ia l lobe, figure 2. The lllin o ia n ground moraine must have been le v e l, fo r th e gum b o til p lain th a t was developed on I t , lik e th a t on the Kansan ground mo rain e, stretched out smoothly fo r mil©#*
The two main drainage lin e s th a t
cross i t , Iowa and Skunk r iv e r s , have wide v alley s th a t nr® incised f a r below the p la in , and in general a d e n d ritic drainage system is f a i r l y well developed.
N evertheless, wide areas o f the gumbotil p lain s t i l l survive,
modified only by the depo-it5.cn over them of several fe e t of loess*
This
loess bears decisive evidence of being of two ages, because in places a lower body of compact leached loess is overlain by unleached loess th a t grades up in to leached lo e s s.
Th® lower loess is la te Sangamon or upper
Loveland in age; th a t i s , post-111inoian-gurabotil, while th e upper loess is the Peorian loess of Iowan age and post-Xow&n age# While the Loveland loess is not found u n iv ersally present in th© lllin o ia n area, I ts exposures are
so generally d istrib u te d th a t there I® warrant in assuming th a t i t s
o rig in al extent over the lllin o ia n d r i f t was comparable to th a t of the Pe orian loess in Early lis e o a e in time* When the Illin o la n g la c ie r crossed the M ississippi v a lle y , i t
••lj.fi.**
Figure £« m p o f 1mm sheering th e extent of lllin o ia n g la c ia tio n l a the s ta te .
-5-
fU Is d t h is v a lle y with lee and g la c ia l debris and forced the riv e r to find a nmt course around the advancing fro n t o f th© ic e -sh e e t.
This stream
course must have continually changed w ith th e a lte rin g lee fro n t, but when the ice f in a lly ©me to r e s t, the w aters o f th© riv e r were ponded by the high lands near Columbus Junction and eventually formed a lake th a t cover ed the present lower course of Cedar riv e r and ©tended f a r up the Cedar and Iowa valley®.
This body of water has been named hake Calvin, and i t s 3 h isto ry hag been traced in d e ta il by Sohoewe and outlined in a l a t e r p a rt
3
-------------------- ------------------ ---------------------- ------------------------------------------Sohoewe , W alter H*# The O rigin ahd H istory of E xtin ct Lake Calvin * lows (tool# Survey, ? o l. XXIX, pp. te-282, 1920* of th is report* O rigin of the D rift The lllin o ia n d r i f t undoubtedly was derived in very large meas
ure from th© older d r i f t sheets over which i t passed*
These were th© Me-
braskan and th© Kansan} but to what extent the lllin o ia n g la c ie r found each of these d r i f t sheet© a t the surface i s , of course, undetermined, as comparatively l i t t l e is known of the d is trib u tio n o f these d r i f t s in the sta te s e a st of Iowa*
Because th© two e a r lie r g la c ie rs cam© from west of
Hudson Bay while the lllin o ia n earn© from th© Labrador peninsula, the course of th© l a t e r g la c ie r would b© nearly a t rig h t angle® to th a t of th© e a r lie r ones, and i t is q u ite possible th a t boulders and other m aterial th a t o rig i nated in th® leew atin region and th a t lodged in th© s ta te s south of the Great Lakes may have been moved westward l a t e r by th© lllin o ia n ice as f a r as western I llin o is or Iowa* The erosive work of th© lllin o ia n g la c ie r would n a tu ra lly be, in the f i r s t place, t© remove any in te rg la c ia l m aterials th a t had accumulated
-6 -
m the o ld er d r i f t sheets or in valley® cut in to them.
Heart would come
the c u ttin g away ©f th e gumbotil®* then of the oxidized and leached t i l l s , th e oxidized and tmleaohed t i l l s * and, i f erosion proceeded fa r enough, th e upper p a rts of th e unoxidized and unleached, t i l l s *
With such a body
of leached m aterials to be scraped o ff, i t seem® remarkable th a t the l l lin o ian d r i f t , as i t was f in a lly c o n stitu te d , should have contained much calcareous matter*
The f a c t, however, th a t any sectio n of lllin o ia n d r i f t
th a t exposes a thickness of te n fe e t o r more does show unleached m aterial is evidence th a t th© lllin o ia n ice did plow deeply in to th e unleashed t i l l and probably, lo c a lly a t l e a s t, in to the bedrock beneath# The Illin o la n d r i f t 's h e e t , th en , comprises unsorted and unsstrati fied bodies of clay and coarser m ate ria li in oth er words, ty p ic a l g la c ia l t i l l s and also masses of sand and gravel th a t were more or lea s asso rted and la id down a® bedded deposits* Changes in th e D rift As soon as the lllin o ia n d r i f t , both t i l l and g rav el, was uncovered, I t became su b ject to th e actio n o f weathering and oth er physical and chemical agencies*
Ha in® and t h e i r consequent surface and subsurface wa
te rs began to dissolve m d re a s s e rt and otherwise modify th© m aterials o f th® d rift*
Plants and animals would a l t e r the te x tu re and composition of
the t i l l , and the gases o f the atmosphere and those produced by chemical reactions would aid in t h is work of change*
I t was not long u n til oxida
tio n of the Iron content and perhaps o f oth er components as w ell a lte re d the color of th e upper p a rt of the d r i f t from it® o rig in a l gray to a y e l lowish ting©.
P a ra lle l w ith th is oxidation, although much slower, was
th© leaching o f th e lira© carbonate and probably other rea d ily soluble e le ments and th e carrying sway of the®® m aterials in th© ground w ater.
-7-
fh® sin g le unleached mid imoxldised zone of the o rig in a l, fre s h , u n a lte r ed d r i f t sheet would thus soon he divided in to two zones, the upper of whieh was oxidised although s t i l l unleaehed, and as a lte ra tio n progressed downward, a th ird son© would b© introduced, the uppermost leashed zone* But a lte ra tio n has not stopped a t th is sta g e, and th e leached m atter has been s t i l l fu rth e r modified! -the clay c o n stitu en ts have been broken down into sim pler compounds, some of whieh have been carried outs the sands, gravels, and even the boulders removed u n til a t present the upper few fe e t of the t i l l contains p ra c tic a lly no boulders and only a few pebbles, these being of the most nearly insoluble types only*
Thin resid u al m aterial is
the Illln o ia n gumbotll and i t seems to have covered p ra c tic a lly a l l the Illinois® d r i f t plain* Illin o is*
Illin ois® gumbotil is exceptionally widespread in
D etailed studies in th a t s ta te have resu lted in the recogni
tio n of zones equivalent to the gumbotil, but which r e f le c t d iffe re n t types of drainage s u ffic ie n tly to m erit separate recognition*
Thus, ty p ic a l,
f l a t upland' areas with poor drainage r e s u lt in gumfootil. W ell-drained areas re s u lt in & s i l t y , comparatively open-textured 'm aterial termed s i l t til.
to t e t o n r t l * . condition of drainage r e m d t. in * product which is
interm ediate in tex tu re (between guabotll and s i l t t i l ) , known as mesotil* n r ~ — !— * ---------------------- and MacGlintock, ]$%ul, Weathered Eones of th e Drift-Sheets of Illin o is^ Jour, Seol*, Vol. 3 f . W* 1930. I t seems remarkable th a t th e thoroughly leached m aterial th a t lie s beneath the gumbotil and th a t grades upward into i t should have a thickness of not over th ree fe e t in most p laces.
This seems to in d icate
th a t leaching progresses very slowly under the p ro tec tiv e cover of the gumbotil.
Complete sections of the Illin o is® may be seen today in which
the t i l l is oxidized to a depth of t h i r t y f e e t, but in which leaching has
-8 -
advsnced only two to seven f e e t below th e gumbotil* However, weathering does not stop w ith th e development o f gtam— b o til* in places t h is layer is s t i l l fu rth e r changed u n til the s tic k y , compact, gusBTGy clay is robbed o f com© o f the co n stitu en ts th a t give I t t h is c h arac ter, and i t becomes a mealy, almost lomalike clay*
Figure 3
is a diagrammatic rep resen tatio n o f a ty p ic a l sectio n o f Illin o is© t i l l showing the succession o f changes which are found in Iowa#
f h i s sequence
of t i l l phases is a lso known as the s o il p r o f ile , and the p r o f ile of weath e rin g . In I l l i n o i s , m eh work has been done on these semes of weather ing * The various horisons have been numbered and are equivalent to the geologic terminology of the t i l l phases as used in Iowa, as shown in the following ta b le j S oil p ro file cj horison number M orW on'X 'Tsurficial s o i l ) Horizon 2
Oumbotil Oxidised and leached phase Oxidised and unleach ed phase Unoxidised and un leashed phase
Horiaon 3 Horison i* Horiaon 5
r -------------------------------------- -— ----------------- ~~~~-------------- --------- Leighton, M* M*,md MaoClintook, Paul, op* o i t *, p* 3£. In the case of gravels lying near the surface sim ila r a lte r a tio n may be expected to tak e place*
Oxidation and leaching would progress much
as in t i l l u n til th e soluble pebbles would b© removed*
I t seems probable
th a t fu rth e r weathering down of igneous material© might even form a residuum
6 sim ilar to gumbotil*
Such m aterial has been given th e name gumbos and*
F Leighton, M* M*,and MaoClintook, Paul, op* o i t # , p# 1*1
tM- t n IBDl* o
►o
» ®
ta o
T o
1
I#
-
.
ent O ~\
O
O
O l^ |n mrn.
r
—
i
0
9
0
**« C * 9 0 O
■ ■ ■ - ■ -
i
,
i
■
Oi O
-j O
< 3 f
>i*. In n" n- 0
P
-
i
m
t
-
m E
F
_
— i/i6 1--------------------------- :------l / B j-------
.
p _L ------- -------
= ; | P — *— 1 /ia I ----- 1---------- 1/3? 1 ------ --------
E -----------
m
™ t ------------------- 1------------1 / M ------------------------------------\------- ------- 1-------
Figure 78*
9
p-’r