!f&-6 14: GS • sou i«54-fc m CD to 10 cB CD o 8 1 X O m O r- O CD O > 00 X > X -< State of Illinois Department of Registration and Educe tion State Geological Survey Division Morris M. Lsighton, Chief MINERAL RESOURCE I RECORDS DlVls l0N ILLINOIS STATE GEOLOGICAL ST mt Ty I Bloomington-Normal Area McLean County Danvers, Normal, LeRoy, and McLean quadrangles Guide Leaflet 54-B George E. Ekblaw, Leader Host: Illinois Wesleyan University Urbana, Illinois April 24, 1954 Mileage Interval Total Bl qomington-Normal Area Itinerary 0.1 0.1 0.1 0.2 0.1 0,3 0,0 Assembly at central parking area, Illinois Wesleyan Univer- sity o Leave parking area, headed north. Turn left (west) on East Emerson St. North East St. Turn right (north). East Kelsey St. Turn left (west). Stop . North Main St. = U. S. Highway No. 51. Turn right (north). 0.6 0,9 Railroad underpass with traffic light just beyond, at Hovey Avenue, Turn left (west). 0,3 1.2 Stop . Adelaide St. Straight ahead. 0,3 1»5 Gravel pits to left (south), in valley- train of glacial outwash along Sugar Creek. 0.6 2.1 STOP _I, Weathering profile on Bloomington glacial drift exposed along north side of road„ Like many other things, rocks and minerals suffer changes when they are exposed to the weat'.ier Although these changes are relatively slow, they become evident in earth deposits that are not disturbed over long periods of time and develop what is known as a weathering or soil profile in the surficial part of such deposits. Following the practice established about 30 years ago by the Russian Glinka, soil scientists usually consider that the soil or weathering profile consists of 3 zones, designated A, B, and C from top down. The A zone is the "soil" zone, which is normally black or gray in color. The B zone is the r - subsoil" zone, and the G zone is the un- altered parent material. The zonal efiect results from the fact that the four principal processes which effect soil weathering all progress with the downward irovement of groundwater but at different rates. These processes, listed in order according to their rate of progress, beginaing with the most rapid, are (l) ..' ■ v 0.2 2.3 0.5 2.8 0.8 3.6 2.3 5.9 - 2 - oxidation, (2) leaching of carbonates, (3) decomposition of more resistant minerals, and (4.) accumulation of humus. Consequently > in the A zone, in which the humus material derived from decaying plants has accumulated, the rock minerals are oxidized, leached, and decomposed. In the upper part of the B zone they are oxidized and leached and in the lower part of the B zone they are only oxidized. The oxidation zone' is shown by the reddish or yellowish color resulting from the oxidation of iron minerals. The leached zone is determined by the absence of carbonates, as revealed by tests with a solution of hydrochloric acid. At this stop the soil profile is developed partly on loess and partly on glacial till that includes small deposits of sandy gravel. Turn right (north) on T-road, Stop . Road intersection. Straight ahead. Outer edge of Normal moraine. STOP II . Crest of Normal moraine. Tens and hundreds of thousands of years ago most of Illinois, together with most of northern North America^ was covered by huge ice-sheets or glaciers. These glaciers expanded from centers in what is now eastern Canada. They developed when for some reasons not yet determined the mean annual temperatures in the region were somewhat lower than now, so that not all of the snow that fell during the winters was melted during the summers. The snow residues accumulated year after year until they became a sheet of ice so thick that as a result of its weight the lowermost part began to flow outward, carrying with it the soil and rocks on which it rested and over which it moved. The pro- cess continued until the glacier extended into our country as far south as Missouri and Ohio rivers. At this time the temperatures moderated. The meeting of the ice first balanced its accumulation and expansion, so that its margin remained stationary. Later the melt- ing exceeded the accumulation and expansion, and the ice front gradually melted back until the glacier disappeared entirely. As the glacier melted, all of the soil and rocks which it had picked up as it advanced wore released. Some of this material or drift was deposited in place as the ice melted. Such material consists of a thorough mixture of all kinds and sizes of rocks and is known as till . Some of the glacial V - 3 - drift was washed out with the melt-waters. The coarsest outwash material was deposited nearest the ice-front and gradually finer material farther away. The finest clay may have been carried all the way to the ocean. Where the outwash material was spread widely in front of the glacier it forms an outwa sh-plain ; where it was restricted to the river valleys, it forms what are called valley- trains ,, Some sand and gravel was also deposited at the edge of or actually within the glacier, by streams of melt-water flowing on, in, or under the glacier c Deposits along the courses of such streams now appear as ridges of gravel and are known as eskers . Deposits made where such streams emerged at the edge of the glacier or emptied into holes in the glacier now appear as more or less conical hills of gravel and are known as kames e At times, especially in the winters, the outwash-plains and valley-trains were exposed as the melt-waters subsided, the wind picked up silt and fine sand from their surfaces, blew it across the country, and dropped it to form deposits of what is known as loess . Glacial loess mantles most of Illinois. Near the large river valleys it may be as much as 60 or 80 feet thick. Far from the valleys it may be measured only in inches, if it can be identified at all. It is now commonly known that there were four major periods of glaci.tion during the Pleistocene or Great Ice age, (see accompanying table) and that between each pair there was a long inter glacial period in which conditions were as they are to-day. It is also commonly known that during each major glrciation there were a number of retreats and readvpncos. This was particularly true during the last or Wisconsin glacial st=:.ge. The position of the ice-front at each advance is marked by a ridge of till or mo raine . The moraine represents the accumul.- tion of drift at the ice-margin while the advance and melting were essentially in balance, when more and more material was being brought to the edge by the advancing ice. When melting exceeded advance, so that the ice-front retreat- ed, the resulting drift daposits form a drift- plain or till- pJLain, whose surface may be almost level or more or less billowly. This stop is on the top of the I irmal moraine, one of the moraines of Wisconsin ago. To the southwest may be dis- c. r.i.d another moraine, the Bloomington, and between them la „ bloomington drift-plain. To the northeast is a third moraine, the Cropsey, and between it aid the Normal moraine lies the Normal drift-pl?in. As shown on the accompanying map of moraines in northeastern Illinois, i . I. . '., . " . 1 i ■■■ 0.5 6.4 0.5 6.9 0,6 7.5 0.5 8,0 1.5 9.5 0.5 10.0 0.4 10.4 0.6 11.0 0.7 11.7 3.2 14.9 0.1 15.0 3.6 18.6 0.8 19.4 0.2 19.6 - 4 - these are only three of several of Wisconsin age. The surface relief of moraines is generally greater than that of the drift-plains. It is generally referred to as s we 11-and- swale, but on some moraines it is termed knob-and- kettle topography. Generally the outer slope and edge of the moraines is interrupted by valleys and re-entrant angles marking the courses of glacial rivers. At some places there ore gaps in the moraines where sub- glacial streams presumably carried away most of the drift. Subglacial valleys may be distinguished from valleys developed by erosion in postglacial time b/ the fact that morainic. topography occurs all the way down to valley slopes. Road intersection. Turn left (west) Sharp job right and left. Road intersection. Sharp job right and left. Continue west. Crest of Normal moraine. Good view to southwest, T-road intersection. Turn right (north). T-road intersection, Turn left (west). Good view south- westerly across Bloomington drift-plain to Bloomingtcn moraine. Stop . U, S, Highway No, 150, Straight ahead on gravel road. Outer edge of Normal moraine, Bloomington drift-plain ahead. Railway crossing, CAUTION STOP III. Loess deposit. At this locality the loess at and near the top of the hill is 8 feet and more thick, so that in contrast with STOP I it is not entirely leached, and at a few restrict- ed places calcareous loess may be found at the base, The calcareous loess lies on calcareous till, showing that there was no weathering interval between their depositions. Stop . Paved road. Straight ahead. Turn right (north). Note "badland" erosion on hillsides. Turn left (west). - 5 - 0.3 19.9 Turn right (north). 0.4 20.3 STOP IV . Park along road north of bridge. Exposure along south side of Rock Creek east of bridge. Successioni- Wisconsin Till, calcareous, brownish-pink Iowan Loess, calcareous, bluish gray, with iron-stained streaks and mottling Farmdale Loess, noncalcareous to slightly calcar- eous in places, brownish gray to yellow- ish gray; iron-stained joints; contains humus streaks and layers; wood fragments at top. Silt, noncalcareous, dork brown, peaty Silt, noncalcareous, dark gray, carbon- aceous Sangamon (on Illinoian) Soil, noncalcareous, dark brown, friable (Horizon l) Gumbotil, noncalcareous, drrk gray, plastic tough; blocky fracture; (Horizon 2) Till, noncalcareous, yellow (Horizon 3) Thickness Ft. In. 20+ U 7 10 As listed above, this exposure reveals a success ">n of glacial deposits beneath more than ,20 feet Of till of Wisconsin age, of which at least the lower part s; >ald be Shelbyville, First, there is a 2- foot layer of gray calcareous loess thrt is correlated as of Iowan age. This loess wrs derived by the wind from outwrsh deposit- ed in Illinois River valley either from the Iowan glacier in Iowa or from the advancing Shelbyville glacier in Illinois. Beneath the Iowrn loess there is about 8 feet of loess and silt of Farmdale age. It is distinguished from the Iowan loess by its darker rnd brownish color, by the fact that it is partly leached, and by the abun- dance of humus, peaty material, and wood fragments. The Farmdale loess and silt are derived from or reLated to outwash deposited in Illinois River valley by a glacier of Wisconsin age earlier than either the Iowan or Shelby- ville glacier. -6- 0.4 20.7 0.3 21.0 0.2 21.2 1.5 22.7 0.4 23.1 0.6 23.7 The mild leaching of the Farmdale deposits shows th<"t there was a brief period of weathering between the Farmdale and Iowan-Shelbyville glaciations. This in turn is evidence that between these glaciations there was an interstadial period of significant duration in which the Farmdale glacier must have receded for if it did not entirely disappear before the Iowan and Shelby- ville glaciers advanced. Below the Farmdale deposits there is about 12 fe:t of Illionian till grectly weathered during the succeed- ing Sangamon interglacial stage. Geologic studies of the soil profiles developed on the older drifts - Illi- noian, Kansan, and Nebraskan - reveal that they can be divided into 5 zones, or horizons, instead of the 3 first recognized by Glinka in the soil profile developed on the Wisconsin drift. In order to avoid confusion they have been designated by numbers instead of by letters. Horizon 1 is the old "soil" or humus zone. Horizon 2 is a dense layer, very gummy and plastic when wet, very hard when dry. Horizon 3 is the leached rnd oxidized zone, and Horizon 4 is the oxidized but calcareous zone, Horizon 5 is the unaltered parent material. The development of 5 instead of 3 recognizable zones in the old drifts results from the fact that they are much more we-thered. The total thickness of the weathering on the old drifts is much greater than on the Wisconsin drift, even where they are overlain by younger drifts. Oxidation, leaching, and decomposition of minerals have all progressed deeper. In addition, another process, the downward transfer of clay miner-ils derived from the decomposition of other minerals originally in the drifts, has not only left Horizon 1 more silty than it wrs originally but has made Horizon 2 much denser and more plastic than it was originally. This dense, plrstic, "gumbo" horizon is so little developed on Wisconsin drift that it is not differentiated. Wisconsin till in road cuts, T-road. Turn right (east). T-road. Turn left (north). Turn right (east). Stop . U. S, Highway No, 150. Continue east on highway. Pink Bloomington till on right. 0.6 24.3 0.3 24.6 0.5 25.1 1.2 26.3 0.8 27.1 1.4 28.5 0.5 29.0 0.3 29.3 1.7 31.0 2.7 33.7 0.5 34.2 2.2 36.4 2.0 38.4 0,3 38.7 3.3 42.0 1.0 43.0 - 7 - Railway crossing. ALERT. Congerville . Slow Leave Congerville. Outer edge of Normal moraine. Yellowish-buff, stony Normal till along north side of road. Also good view across Shelbyville drift-plain to south. Turn left (east) on good gravel road (Hudson road). Crest of Normal moraine. Sharp jogs left and right Inner edge of Normal moraine. T-road, Turn left (north). T-road,, Turn right (enst). Stop . U. S. Highway No. 51. Turn left (north). Turn right (east) on paved road to Lake Bloomington s Railway crossing. CAUTION. Stop. T-road, Turn left (north). §Ip~=' k-k e Bloomington spillway. Turn around before parlcing This exposure is relatively unique in that at least 4 separate drifts of Wisconsin age may be differ- entiated, one above the other. Succession:- Thiokness Ft. In. Normal till, clayey, gravelly, buffish gray in upper pr-rt, reddish gray in lower third; discontinuous layer of yellow oxidized sand and silt, up to 6 inches thick about 6 feet above base 18 Interstadial: Clay, pink to purple, lamin- ated over clay, silty, greenish; discon- tinuous 4 - 8 - Bloomington till, gravelly, light gray, part- ly oxidized to brownish gray 6 10 Interst-".dial: peat and peaty silt, crlcareous, fos si lifer ous with mo Husks and wood frag- ments, discontinuous 6 18 LeRoy till, clayey, greenish gray 6 8 Shelbyville till, hard, jointed, purplish gray, upper 8 inches slightly leached, humus darkened, and marked by a pave- ment of pebbles, cobbles, and boulders, all faceted, pdished, -md strirted on top, base not exposed. 8 The distinct breaks and the interstadial materials deposited between the tills are convincing evidence that (1) after the deposition of each of the lower tills the glacier must hrve retre- t-jd a considerable distance and (2) an -"pprecirble interval of time elapsed before the succeeding glacier advanced over the area. Turn left (east) off highway, to picnic grounds. STOP VI . Lake Bloomington picnic grounds. LUNCH . After lunch return to public road. Turn left (south). Turn right (west), CAUTION . T-road. Turn left (east), T-road, Turn right (south), T-road. Turn right (west). T-road. Turn left (south). Stop . County road, paved. Straight ahead. Inner edge of Normal moraine. The Normal moraine here actually consists of two ridges, separated by a narrow intraglacial valley. Farts of this valley are now occupied by the upper courses of Sixmile and Money creeks, with an abandoned portion between, extending two miles westerly from Towanda. 1,0 50.3 Cr-st of inner-ridge of Normal monine. 0.5 43.5 0.2 43.7 0.2 43.9 0.8 44.7 0.5 45.2 0.3 45.5 1.0 46.5 0.5 47.0 1.5 48.5 0.8 49.3 0.6 50.9 0.5 51.4 0.4 51.8 1.5 53.3 0.3 53.6 0.2 53.8 0.5 54.3 0.2 54.5 1.5 56.0 1.0 57.0 0.5 57.5 2.0 59.5 0.6 60.1 1.9 62.0 2.0 64.0 0.4 64.4 0.8 65.2 0.5 65.7 0.9 66.6 0.3 66.9 0.3 67.2 - 9 - Sharp hill half a mile west (right) is a kame. Intraglacial valley. Inner end of subglacial valley through principol Normal moraine, The route follows this valley for a little more than half a mile. Stop. U. S. Highway No. 66. Caution. Turn right (west) on highway. Agfin crossing subglacial channel near point of drainage divide b^tw-^en waters flowing northward through Sixmile Creek and those flowing southward to Sugar Creek. Y- junction. Bear left (easterly). Overpass over railway. Axis of crest of Normal moraine, but not apparent because of subglacial channel which the route here follows for nearly a mile. Railway crossing. CAUTION. New General Electric plant under construction to left (east side). Caution . Traffic light . Intersection with State Highway No. 9. Straight ahead. Outer edge of Normal moraine. Traffic signal . U. S. Highway No. 150. Turn left (south) on U. S. 150. Railway crossing. Caution . Inner edge of Bloomington moraine. Crest of Bloomington moraine. Turn right (south) on gravel road. Gillum . Caution . Jog left and right over unguarded railway crossing. Outer edge of Bloomington moraine. Kickapoo Creek. Valley- train terrace about 10 feet high is conspicuous on the southeast side of the stream. On valley- train terrace. Lower terrace level. » ■' * 10 0.3 67.5 Inner edge of LeRoy moraine. 1.3 68.8 Sag between back and principal ridges of LeRoy moraine. 0,7 69.5 STOP VII . Crest of LeRoy moraine. The LeRoy moraine is a low but broad moraine. East of here it consists of two ridges — a relatively prom- inent frontal one and a less prominent, wider ridge on the back slope. West from here the back ridge increases in size and prominence,, It trends northwesterly to the vicinity of Shirley, whence it trends southwesterly along the southeast side of Sugar Creek, following what was evidently a re-entrant angle in the ice-front. A third component ridge of the moraine exists for a short distance in front of the principal ridge also west of here. It diverges from the main ridge northwest of Heyworth and remerges with it south of McLean. (See topographic map of McLean quadrangle.) There are several subglacial channels across the LeRoy moraine. Kickapoo Creek follows one of them. 0.7 70.2 Outer edge of LeRoy moraine. 0,9 71.1 Note general level but undulatory surface of Shelbyville drift-plain which is now being traversed. 0,9 72.0 Stop. U. S. Highway No. 136. Turn right (west) on high- way, Heyworth . Slow. Railway crossing. Caution. Stop . U. S. Highway No. 51. Straight ahead. Turn right into field. ST 0P.VI II. Van Horn's gravel pit. This pit, like many others along Kickapoo Creek, exploits the glacial outwash that was deposited as a valley-train along the stream. The genesis of the deposit is revealed by the general horizontal attitude of the beds and by the size-gradation of the materials, which are not only uniformly graded at any one horizon but de- crease in average size from bottom up c Sand, silt, and finally clay comprise the surficial materials. 3.6 75.6 0.4 76.0 0.2 76,2 1.5 77.5 - ! -- : •■ ".' ■'•i-J' . •; U: - 11 - 0.1 77.8 0.6 78.4 2,0 80.4 0,2 80 a 6 0.6 81.2 1.1 82.3 0.9 83.2 0*8 84.0 0.4 84.4 It may be noted that the gravel occurs at three levelso The lowest level is the alluvial flood-plain of the stream. Above this is a low terrace, and then the terrace in which this pit is located is 12-15 feet above the flood-plain* This terrace appears to represent the top surface of the original valley- train., Subsequent erosion by the stream has reduced parts of it to the lower levels » What appears to be a still higher terrace level along the sides of the valley is believed to b3 the original slope of a subglacial channel in the Shelbyvile driftc The valley of Kic!:apoo Creek was maintained as a subglacial channel through both the LeRoy and Blooming- ton moraines^ Consequently it served as an escape route for the melt-waters not only from these two but also from the Normal glacier., This accounts partly for the abundant outwash deposits now in the valley. Conditions existing at the time these glaciers melted must have been another factor, as outwash from the Bloomington and Normal glaciers is abundant in all valleys that served as drains for their melt-waters. Return to highway. Turn right (west). Low- level terrace on left (south) side, high-level terrace on right (north) side of highway. Turn right (north) on gravel road. Cuter edge of extra fore-ridge of LeRoy moraine. Crest of fore-ridge of LeRoy moraine. Sag between fore and principal ridges of LeRoy moraine. Crest of principal ridge of LeRoy moraine. Sharp jog right and left. Turn left (west) into lane leading to Mr. LaFayette Funk's home. STQP^TX , Examination of Mr, Funk's collection of minerals and rocks. Mr c Funk's generous invitation to include this examination on the trip is greatly appreciated,. 1 , -.. - j .- i v ■ . ■ • • •-. . ' ■ ' I ' ILLINOIS STATE GEOLOGICAL SUfivlr GLACIAL GEOLOGY IN NORTHEASTERN ILLINOIS Compiled by George E. Ekblaw from data furnished by the Survey January 1, 1942 (71330— 5M— 5-53) Time Table of Pleistocene Glaciation (after M, M. Leighton and H. B. Willxian, 19$Q) Stages Sub-stages Nature of Deposits Special Features Recent Soil, infant to youthful pro- file of weathering, lake and river deposits, dunes, peat Wisconsin (Uth glacial) Late Mankato Early Cary Tazewell Iowan Farmdale (Pro-Wise ) Fluvial deposition - Mississippi , Illinois, and Ohio river valleys; dune sand, some loess deposits along Mississippi River Valley; and deposits in Lake Chicago, Drift, loess, dunes, beginning of deposits in Lake Chicago Drift, loess, dunes, lake deposits. Drift, loess, dunes Loess (in advance of glacia- tion) Lake Agassiz Torrent eroded Late Mankato deposits Lake Duluth Torrent eroded Early Mankato deposits Forest bed, Two Creeks, Wisconsin Kankakee and Lake Mauraee Torrents Fox River Torrent Westward diversion of Mississippi River into Iowa by Tazewell ice lobe Sangamon (3rd interglac lal) Soil, mature profile of weath- ering, alluvium, peat Illinoian (3rd glacial) Euffalo Hart Jacksonville Payson (terminal) Loveland (Pro-Ill, ) Drift Drift Drift Loess (in advance of glacia- tion) Yarmouth (2nd interglac. Lal) Soil, mature profile of weath- ering, alluvium, peat. Kansan (2nd rlacial) Drift Loess Aftonian (1st interglac: Lal) Soil, mature profile of weath- ering, alluvium^ peat s Nebraskan (1st glacial) 1 Drift '