The topography of the county has been thoroughly delineated by the State Geological and the United States Geological surveys, as well as by experts connected with the University of Illinois, especially by Prof. C. W. Rolfe of the Illinois State Laboratory of Natural History. Based upon such authorities, it is found that the altitudes of the incorporated cities and villages in the county are as follows: Ludlow, 770; Champaign, 741; Rantoul, 756; Urbana, 718; Philo, 737; Tolono, 733; Thomasboro, 731; Fisher, 721; Pesotum, 715; Mahomet, 709; Sadorus, 691; Ivesdale, 679; Longview, 678; St. Joseph, 676; Sidney, 673; Homer, 661.
Action of Glaciers
A consideration of these elevations and others in other portions of the county indicates a general inclination of the land surface from northwest to southeast, although, as stated, there is a distinct water-shed which divides the Wabash system from that of the Illinois and the Mississippi. This general trend was determined by glacial action, the great ice sheet moving down from the north, scouring off the land, its successive onward stages being indicated by ridges or, geologically speaking, moraines, which rise above the surface of the surrounding country to heights varying from twenty to a hundred feet. The glaciers which moved across what is now Champaign County were portions of what have become known as the Bloomington and the Champaign systems, the former, which plowed across the northeast corner, being bold and aggressive in character and leaving behind ridges from fifty to a hundred feet high. The streams have cut these into knolls or hills, creating the most considerable heights in the county near Ludlow, from 820 to 830 feet above sea level; near Dillsburg, from 810 to 820 feet, and just east of Gilford and Flatville, 820 feet. The second moraine enters from Piatt County in a series of ridges which join the Bloomington system when well within Champaign County. The main ridge enters near Mahomet, is broken by the Sangamon River, its heights ranging from 750 to 670 feet, and after reaching out into the central parts of the county, breaks into three distinct ridges and passes over into Vermilion County. At Rising, where an altitude of 810 feet is reached, the large branch which connects the Bloomington and Champaign systems, is given oft to the northeast. These moraines are the watersheds of the Wabash and Mississippi basins. No other single agent has been so potent in the modification of the surface of the earth as have glaciers and ice sheets; and this statement applies with particular significance to central Illinois and Champaign County. When it is remembered that these ice sheets were hundreds and possibly thousands of feet thick, and were hundreds of miles in width and length, some adequate idea may be formed of their power to plow up and completely change the surface structure of the earth. The debris which they brought from the Laurential mountains of Canada was distributed over Illinois generally, greatly to the enrichment of its soils. This material, which eventually became the wonder-fully productive soil in all the glacial areas, was transported in several ways. Much of it was pushed along mechanically in front of the advancing ice-sheet, so that when the forward movement began to be retarded, this material was left scattered along the edges of the advancing body. Much material was carried along under the ice-sheet and was ground and distributed over the glacial area. Other material, again, was carried to the surface of the ice-sheet, and often deeply imbedded in it. When the movement was finally checked, the superimposed material becoming heated by the sun, worked its way through the ice and rested on the ground, the whole body of ice eventually melting. Vast quantities of material were also carried by the streams which continually flowed from the melting ice. Much of the detritus was left on the broad, flat prairies, but much was carried into the streams which overflowed their banks, where it was deposited as alluvium. The material which these glaciers brought into the State of Illinois, as the basis of her vast material wealth, goes under the general name of Drift. Its composition varies, but its main constituents are clay, sand and boulders. This drift is sometimes found stratified, but more generally is without definite layer formation. Without going into details as to authorities, it may be stated that, in North America, there seems to have been three great centers of glacial movement one known as the Labrador ice sheet; a second called the Kewatin ice sheet, and the third, the Cordilleran ice sheet. The first sheet had its center of movement near the central point of the peninsula of Labrador; the second, near the western shore of Hudson Bay, and the third moved from the Canadian Rockies. The ice sheet, the center of which rested on the Labrador peninsula, moved northeast, northwest, south and southwest, the movement in the direction last named starting a large section of the vast body toward what is now the State of Illinois. The Labradorean sheet reached its extreme southern limit in southern Illinois, some 1,600 miles from the point of departure. The advancing front in Illinois took the form of a gigantic crescent, and its extreme southern reach, according to the most recent geological surveys, may be traced from Randolph County southeast, through the southern side of Jackson eastward through southern Williamson, east and northeast through southeastern Saline, northeastward to the Wabash through the northwest corner of Gallatin and southeastern White. That line also marks the southern limit of the prairie areas, and is coincident with the northern foothills of the Ozark Mountains, which trend east and west across the State through Union, Johnson, Pope and Hardin. According to the more recent investigations, Illinois was subject to at least four ice-sheet invasions. In the order of time, these were (a) the Illinois sheet, which covered nearly the entire State; (b) the lowan sheet, moving over the area bounded by the Rock River on the west, Wisconsin on the north, Lake Michigan on the east, and on the south by a parallel extended from the southerly bend of that body of water; (c) the Earlier Wisconsin, covering the northeastern fourth of Illinois, and (d) the Later Wisconsin, plowing out the western borders of Lake Michigan and extending some fifty or sixty miles westward. The Illinois ice-sheet is the one, obviously, which included Champaign County in its operations. The details of its work, in this more limited area, have already been given.
Source: A Standard History of Champaign County, Illinois, by J. R. Stewart, published by The Lewis Publishing Company, Chicago And New York, 1918.