BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA V o l. 36. pp. 417-428 Ju n e 30. 192s

GLACIAL KANKAKEE TORRENT IN NORTHEASTERN ILLINOIS 1

BY GEORGE E. EKBLAW AND L. F. ATHY {Read before the Society December SO, 1921f.) CONTENTS Pago Introduction...... 417 Evidence of torrential conditions...... 410 Fossil bars...... 419 Abandoned high-level channels...... 420 Erosional effects...... 421 Change in topography at limit of torrent...... 422 Alluvial deposits...... 422 Consistent relation of levels...... 422 Supplementary relations...... 422 Nature and extent of torrent...... 423 Source of water...... 425 Age and history of torrent...... 426 Conclusion...... 427

I ntroduction Widespread deposits of sand and rubble extend throughout the entire valley of , from its headwaters in northwestern Indiana to its confluence with Des Plaines River in northeastern Illinois. The complex origin of these deposits has been gradually unfolded as new data on the conditions of glacial drainage have been obtained. Most writers have associated all or part of these deposits with some sort of lake, but the character and geological relations of such a lake have never been definitely or satisfactorily determined. The present study is a con­ tribution to the solution of the complex problem and suggests lines of further investigation. 1 Manuscript received by the Secretary of the Society December 30, 1924. Published by permission of the Chief, Illinois State Geological Survey. Paper read by the senior author. Introduction by M. M. Leighton. * (417)

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/36/2/417/3414628/BUL36_2-0417.pdf by guest on 01 October 2021 418 GLACIAL KANKAKEE TORRENT IN NORTHEASTERN ILLINOIS Probably the first geologic recognition of these deposits was incidentally recorded by Shepard,2 who asserted that evidence of the occasional over­ flow of Lake at ancient periods exists along the Kankakee Valley. Later investigations have proved that this view of the relation with is erroneous. Bradley3 presented the first general description of the appearance and extent of the sand deposits and con­ cluded that the Kankakee Valley is the basin of an extinct lake, which he called . Chamberlin4 doubted the adequacy of Brad­ ley’s explanation and proposed as an alternative a “lacustral river.” He pointed out that “this region must have been the avenue of discharge of vast quantities of water shed from the adjacent slopes of the great gla­ ciers occupying the basins of Lakes Michigan, Huron, and Western Erie,” and further suggested that the great accumulations of sand origi­ nated in “this exceptional drainage but were subsequently modified by fluvial, lacustrine, and eolian action. Leverett,5 6 who doubtless has made the most comprehensive examination of this region, considered the area to have been occupied at first by several noncontemporaneous, marshlike lakes of small extent and shallow depth, on the borders of which there was outwash from successive positions of the fronts of the receding Mich­ igan, Saginaw, and Erie ice-lobes. He further states that “the existence of certain low-lying tracts strewn with boulders and nearly free from sand, amid bordering higher sand-covered areas, suggests that patches of stagnant ice persisted while the sand was being laid down.” 7 He con­ sidered that later, when the ice-lobes were at the positions shown in figure 4, the waters derived from their melting found an outlet and de­ posited additional sand along the Kankakee Valley. Evidence obtained in 1923 by Ekblaw, during his detailed study and mapping of the Kankakee Quadrangle, Illinois, confirms Chamberlin’s suggested explanation, refutes the existence at any time of a lake in the Kankakee Valley, at least in the vicinity of Kankakee and Momence, explains the boulder-strewn tracts as areas from which finer materials have been eroded, and involves a new conception of the drainage condi­ tions during a part of glacial times. 2 Charles Upham Shepard: Geology of Upper Illinois. American'Journal of Science and Arts (Sillim"n’s Jo-irna’.), vol. 34. July, 1838, p. 137. 3 Prank H. Bradley : , vol. tv, 1870, pp. 227, 236. 4 T. C. Chamberlin : Preliminary paper on the terminal moraine of the second Glacial epoch. U. S. Geological Survey, 3d Annual Report, 1881-82 (pub. 1883), pp. 330-331. 5 Frank Leverett: The Illinois Glacial lobe. U. S. Geological Survey, Monograph 38, 1899, p. 338. • Frank Leverett and Frank B. Taylor : The Pleistocene of Indiana and Michigan and the history of the . U. S. Geological Survey, Monograph 53, 1915, pp. 128- 130, 207, 219. 7 Leverett and Taylor: Op. cit., p. 128.

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/36/2/417/3414628/BUL36_2-0417.pdf by guest on 01 October 2021 EVIDENCE OF TORRENTIAL CONDITIONS 41 9 Torrential bars composed of surprisingly coarse material and old channels were discovered at high levels. Over a wide stretch of territory the till has been removed with a consequent concentration of boulders. All the evidence points to a great torrent of glacial waters from the Michigan, Saginaw, and Erie lobes of the Wisconsin ice-sheet, which was discharged through the Kankakee Basin during the Valparaiso glacial stage. The ordinary drainage lines which were already developed could not accommodate this torrent, and it spread over the depression between the on the south and the later morainic belts on the north, stripping the bedrock of its drift mantle, heaping gravel and slabs of limestone into bars in the lee of rock hills, and depositing sands and silts in the quieter reaches along its outer border. This torrent is called the Kankakee Torrent and its discovery brings into clearer light the hitherto obscure conditions of drainage in the lower end of the Kankakee Valley. During the summer of 1924 Athy found much corroborative evidence in his study and mapping of the Herscher Quadrangle, which adjoins the Kankakee Quadrangle on the west. He is able to point out the im­ portant bearing which the widespread waters had on the hitherto prob­ lematical sand deposits in the vicinity of Coal City and Dwight. The composite results of these studies are summarized in this paper. The work in both quadrangles was performed under the auspices of the Illinois State Geological Survey and under the personal supervision of M. M. Leighton, Chief of the Survey, whose knowledge of the Pleistocene of northern Illinois enabled him to give much valuable help. The val­ uable comments and suggestions of Prof. Frank Leverett are also ac­ knowledged. E v id e n c e o f t o r r e n t ia l C o n d it io n s FOSSIL BARS The most striking evidence of torrential conditions is presented by fossil bars. They are composed almost entirely of slabs and smaller frag­ ments of local dolomitic limestone, with a small proportion of erratics. They vary in size from pebbles to flat slabs two feet or more in length and four to six inches thick, with cobbles and boulderets comprising the major part. Sand and silt are present only as interstitial filling. The pebbles are mostly crystalline erratics and are well rounded; the cobbles and boulderets are subrounded to subangular; and the larger slabs of limestone are angular, with little or no rounding on the corners and edges. The material is poorly sorted and the rude stratification appears io parallel the slope of the ridge in which it occurs. Some of the rubble

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/36/2/417/3414628/BUL36_2-0417.pdf by guest on 01 October 2021 420 GLACIAL KANKAKEE TORRENT IN NORTHEASTERN ILLINOIS bars are completely covered with clean, uniform sand and are distin­ guished with difficulty from dunes unless their cores are exposed. This may explain Avhy the true character of the bars was not discerned in the earlier and less detailed investigations. The best examples of this rubble are found in the western part of the Kankakee Quadrangle and in the eastern part of the Herscher Quadrangle. The bars appear as isolated mounds or as single and combined ridges. They range from low swells, barely perceptible above the general flat, to conspicuous elevations forty feet high, where sand is piled up in dunes. They vary in width from a rod or two to over a quarter of a mile, and some are apparently united to produce a greater width. They may be only a few rods or as much as three miles in length, with a straight or slightly sinuous outline. The summits of most of the ridges are undu­ lating, due either to irregular accumulations of the gravel and rubble or to development of sand dunes.

F i g u r e 1 .— Gravel Pit in Rubble Bar in Section 17, Township 31 North, Range 11 East The size and angularity of the fragments, the poor sorting, and the rude stratification are well exhibited. There is a pronounced parallelism in the alignment of the ridges, which are oriented in the direction of the current. Frequently some low rock remnant is found at the upstream end of the bars. This served to divide the current, and in the eddy behind it were deposited the large rock fragments which the torrent had ripped from the rock bed over which it rushed. In the interstices smaller fragments and sand and silt found lodgment. ABANDONED HIGH-LEVEL CHANNELS Across the moraines which form the walls of the Kankakee Valley are numerous channels whose floors are now between 630 and 660 feet in elevation. These channels vary in width from a quarter of a mile to over two miles. The small streams which now drain these valleys could

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/36/2/417/3414628/BUL36_2-0417.pdf by guest on 01 October 2021 EVIDENCE OF TORRENTIAL CONDITIONS 421 never have developed them. Abundant deposits of sand and gravel are found along some of them. One channel crosses the Marseilles moraine on the south side through a narrow gap just north of Chebanse. At its southern aperture is an abundance of sand and fine gravel. Another gap in this moraine is the broad, flat valley in which the present Iroquois River has incised itself. On the north side of Kankakee River a moraine younger than Minooka and older than Valparaiso is interrupted by side channels of the Kankakee Torrent, which are now occupied by Soldier, Davis, and Rock creeks. Be­ hind this moraine a broad and well-developed valley runs north­ west from Exline toward Man- teno, and then westward along South Branch. EROSIONAL EFFECTS The effects of erosion that the Kankakee Torrent would be ex­ pected to develop arc as pro­ nounced as those of deposition. The side channels have already been described. A steep bluff was cut by the torrent along the moraine at Kankakee and east­ ward to Exline. Another bluff appears to the east and becomes particularly pronounced at and east of Momence. Nearly all of the till that must once have bjeu

present in the Kankakee Valley F i g u r e 2 .— Detail of Rubble in Section 3~>, was swept away by the torrent. Township 31 North, Range 10 East. At a few places where a road cuts Note size, angularity, and poor sorting of through a ridge or mound, rem­ materials. nants of this till may be found beneath several feet of sand or gravel. The removal of the till bared the bedrock, and a smooth, relatively flat or gently undulating surface at about the 620-foot elevation was devel­ oped on it. Projections 10 to 30 feet high, in the lee of many of which are found sand or gravel deposits, were left above the general level of this surface. The surface of the rock has been weathered very slightly and shows no vidence of glacial action, such as polished or striated sur­

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/36/2/417/3414628/BUL36_2-0417.pdf by guest on 01 October 2021 422 GLACIAL KANKAKEE TORRENT IN NORTHEASTERN ILLINOIS faces. In the areas between the fossil bars the rock is now covered with a mantle of sandy or silty soil varying in thickness from an inch or two to three or four feet. In these areas, also, boulders occur in abundance. Some of them are as much as 12 feet in diameter. Most of them are residual from the till which was swept away, although some may be ice- transported. CHANGE IN TOPOGRAPHY AT LIMIT OF TORRENT The lateral limits of the Kankakee Torrent are indicated by a consid­ erable change in topography at a consistent line which can be traced around nearly the entire basin and which shows a downstream descent. Above that line the surface is irregular—partly morainic, partly ero- sional; below that line it approaches flatness, interrupted only by the fossil bars. At many places the exact limit can be definitely distin­ guished by a slight but abrupt break in slope. ALLUVIAL DEPOSITS Alluvial deposits of some sort are found everywhere in the Kankakee Basin below the upper limit of the Kankakee Torrent. The fossil bars of rubble, gravel, and sand, separated by areas of sandy or silty soil, have been described. Sand and gravel deposits are found along the abandoned channels. Sand or silt is found up to, but not above, the limit of the water on the slopes of the moraines which form the walls of the valley and in those areas where there were quiet reaches along the outside of the torrent. This silt and sand is grayish yellow, noncalcareous, with less than 2 per cent of small pebbles. The contact between the till and the silt is uneven and is generally marked by a thin layer of gravel, with pockets of coarse sand in the depressions. CONSISTENT RELATION OF LEVELS When assembling all of these evidences, the consistency of their upper limits becomes an evidence in itself. The rubble is never found above 660 feet. The abandoned channels are all below 670 feet. The till bluffs lose their steep slope above 660 feet. The change in topography occurs at a line that lowers from 660 feet in the east to 650 and 640 feet in the west. The alluvial deposits all occur below this line.

S upplementary R e l a t io n s Although the observations of the authors are limited to the local area represented by the Kankakee and Herscher quadrangles and the imme­ diately contiguous territory, the interpretation that has been derived

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/36/2/417/3414628/BUL36_2-0417.pdf by guest on 01 October 2021 SUPPLEMENTARY RELATIONS 42 3 applies to an extensive region. It is directly applicable to the whole of the main Kankakee Valley and to its immediate slopes. In Illinois the northern boundary of the main Kankakee Valley is formed by the mo­ raine that is younger than Minooka and older than Valparaiso, although across and behind it are several side channels. These are in turn limited on the north by other morainic ridges. Farther east the Valparaiso and Kalamazoo moraines apparently form the northern bank of the torrent. The conditions relating to the Kankakee Torrent are closely connected with a late phase of those relating to the flooding of the Iroquois Basin, which had an outlet through Vermilion Eiver to the west at and possibly after the time the Marseilles moraine was being built. The Marseilles moraine, which formed in general the southern bank of the Kankakee Torrent and thus separated it from the Iroquois Basin, has gaps across it which allowed connections between the two basins when the floods were at high levels. This moraine also forms the constriction across the Illinois Eiver valley, behind which the torrential waters were held until they reached a level at or slightly above 640 feet and consequently spread widely over the entire Morris Basin. Through this lacustral body of water a direct current was maintained from the Kankakee Valley to the outlet across the moraine. The sands and silts that now are found abundantly only in the southern part of the Morris Basin were deposited in the quieter water on the south side of the current. These deposits were supplied by the torrent but prevented by the current from being carried in any great amount to the north side of the basin. It may be found later that some of the beachlike ridges in the Morris Basin are related to some stages of the torrent. When the Morris Basin was flooded the lower parts of the Des Plaines and Du Page valleys were also- filled to the same level. The erosive action of the Kankakee Torrent may have developed the abrupt southern terminations of the Minooka till ridge, which separates the Morris and Des Plaines basins, and of the immense gravel deposits that form terraces along Des Plaines Eiver. There is a possibility that the flat top of the southern part of the Minooka ridge, which is below the 640-foot level, resulted also from erosion by the torrent.

N a t u r e a n d E x t e n t of T o r r en t The Kankakee Torrent extended from southern Michigan, across northwestern Indiana and northeastern Illinois, along Kankakee River, and then down . The whole expanse of water varied in width from 5 to more than 12 miles. The depth of the cutting by the XXVIII—B o ll. Geol. Soc. A m ., V ol. 36, 1924

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/36/2/417/3414628/BUL36_2-0417.pdf by guest on 01 October 2021 on 01 October 2021 by guest Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/36/2/417/3414628/BUL36_2-0417.pdf LCA KNAE TRET N OTESEN ILLINOIS NORTHEASTERN IN TORRENT KANKAKEE GLACIAL

LEGEND V//Ä Morainic Areas KWM Large Sand Tract !$% ä RMb Tracts Rubble Bors Sand Ridges, some containing rubble cores...... Boundary Approximate ----- Exact Boundary Unknown Sca/e of Mí/es 8---- 1----¡

F i g u r e 3.— Map showing the Extent of the Area covered by the Kankakee Torrent in Illinois and the Parallelism of the Sand Ridges and Rubble liars in the Kankakee and H erseher Quadrangles NATURE AND EXTENT OK TORRENT •125 main torrent was aproximately 30 feet, as shown by the bluffs near Kankakee and Momence. The torrent developed sufficient power to erode its channels cleanly and to carry material at least as coarse as that found in the rubble bars. The volume of water that was contributed created a current that flowed through the wide lacustral flood to and through the constriction in the Marseilles moraine. On the sides of the main current were quieter slack- water eddies. In the main current, wherever the current was checked, bars were developed; in the eddies the silts and fine sands were more

F i g u r e 4 .— Map showing the Relation of the M ichigan and E rie Ice-lobes to Kankakee River about the Time of the Kankakee Torrent The broken line includes the area shown in figure 3 ; the solid line outlines the Kankakee and Herscher quadrangles. (After Leverett.*) evenly deposited. As the torrent subsided, it assumed the appearance of a braided stream, and finally was confined to a single channel.

S o u r c e op W a t e r This large volume of water was supplied by the Michigan, Saginaw, and Brie ice-lobes, whose unusual relations were first pointed out by Chamberlin.9 Their interlobate contacts were the loci of an immense 8 Frank Leverett: Ann Arbor Folio, Geologic Atlas of the United States, 1908. 9 T. C. Chamberlin : Op. cit., pp. 328-330,

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/36/2/417/3414628/BUL36_2-0417.pdf by guest on 01 October 2021 426 GLACIAL KANKAKEE TORRENT IN NORTHEASTERN ILLINOIS amount of crushing and crevassing—conditions that contributed to rapid melting and facilitated ready drainage from the interior of the ice. The surfaces of the glaciers sloped' toward the interlobate areas and concen­ trated at their margins the discharge of all of the waters derived from the melting of areas far behind. The marginal melting was unusually rapid, also, as evidenced by the pitted qutwash plains which Leverett and Taylor10 found so abundant before the recessional moraines in In­ diana and Michigan. All of these factors created a great volume of glacial waters, all of which had to pass down the Kankakee Valley. That avenue of discharge was used until the Michigan lobe had retreated far enough to permit Saint Joseph and Pawpaw rivers to cut through the moraines and divert their drainage into the incipient and until the Erie lobe retreated far enough to free Wabash River to the south. The abundant outwash plains mentioned previously are evidence both of the great amount of drainage from the ice and of the great amount of debris present, which doubtless supplied much of the finer material that is found in the lower part of the Kankakee Basin and also in the Morris and Iroquois basins.

. A ge a n d H isto r y of T o r r e n t Since the Kankakee Torrent cut channels through and behind a mo­ raine of the Wisconsin series younger than Minooka, it must be younger than that moraine. Streams that cut through later ridges to the north have along their banks abundant deposits of sand and gravel that appear to be correlated with those along the torrential channels, indicating that the torrent is younger than those moraines. It appears to be contem­ poraneous with the advance, halt, and retreat of the Michigan ice-lobe during the formation of the main . In his descrip­ tion of the Camp Custer area,11 Leverett shows that a great glacial stream occupied the Kalamazoo Valley and emptied into the Kankakee Valley during the formation of the Charlotte moraine. This moraine he considers the correlative of the Valparaiso moraine; so that the glacial river which he mentions was probably one of the headwaters of the Kankakee Torrent. The torrent ceased to exist before the opening of the Chicago outlet, for, in the valley of Illinois River, terraces belonging to the outlet succeed those belonging to the torrent. When this volume of water was poured into the Kankakee Valley the Illinois River gap in the Marseilles moraine was an inadequate outlet for it, and it spread out over the adjacent territory until it reached a M Frank Leverett and Frank B. Taylor: Op. clt. 11 Frank Leverett: The Country around Camp Custer, 1918.

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/36/2/417/3414628/BUL36_2-0417.pdf by guest on 01 October 2021 AGE AND HISTORY 01? TORRENT 427 level grading back from the 640-foot elevation along the moraine. At that level the outlet was sufficiently large to allow an outflow that bal­ anced the inflow. When the supply of water became less and the torrent began to subside, it may have assumed the appearance of a braided stream. As the several currents passed between the bars they deposited sand and silt on the flanks of the bars and, in the final stages, in the flats between the ridges. At last the waters were so decreased in volume that they were confined to a single channel, and as they continued to decrease they left successive terrace levels along the sides of the valley. Only the present Kankakee Kiver, a dwarfed descendant of the Kankakee Torrent, now remains in the rock valley in which it. has incised itself.

C o n c l u sio n " Although the Kankakee Torrent is firmly established in the opinions of the authors, much substantiating work remains to be done. The new interpretation has opened up new lines of study. Much information can be gained from a study of the upper Kankakee Valley. The Iroquois Basin presents a big problem. Undoubtedly it has been flooded, but the relations of this flood to the Kankakee Torrent are yet to be discovered. The history of its outlet through Vermilion Eiver is an important prob­ lem in itself. The desirability of new studies in the Morris and Des Plaines basins has been suggested. A further study of Illinois River below Marseilles, and especially below La Salle, where Vermilion River flows into it, is necessitated. In fact, much of the history of the Late Wisconsin ice-sheet in this region is involved in the solution of the numerous ramifications of the problem which is introduced'by the dis­ covery of the Kankakee Torrent.

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