The Illinoian and post-Illinoian Pleistocene geology of Iowa

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m

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