- Physiographic provinces of Illinois
Physiography is the study of the creation and gradual change of land surface forms (the landscape). Thus, the land surface as we see it today in each of the physiographic provinces has had a particular history of development. Driftless Area Wisconsinan Moraines Illinoian Till Plain Mississippi River Wabash River Shawnee Hills Ohio River - The earth with a segment removed to show supposed internal zones
Crust (6-30 miles) Mantle (1800 miles) Outer core (1400 miles) Inner core (750 miles) The core is the innermost zone of the earth. It is mainly iron with some nickel and cobalt. The inner core probably is solid, but the outer core may consist of the same elements in a molten form. The core is the most dense (heaviest) of the three zones. - Extent of the main glacial advances
Extent of the main glacial advances which began with the Nebraskan (a—the oldest) and ended with the late Wisconsinan (f—the youngest). Diagram “d” shows the major stream development during the time between the Illinoian and the earliest Wisconsinan glaciers. The heavy lines on the diagrams indicate major stream valleys that were present during these times. a. Inferred limit of NEBRASKAN glaciation b. Inferred limit of KANSAN glaciation c. ILLINOIAN glacial advance d. SANGAMONIAN major drainage e. Maximum WISCONSINAN glacial advance f. Late WISCONSINAN Valparaiso front and Kankakee Flood - Limits of ice age glaciers
In Canada vast thicknesses of snow and ice accumulated until the weight of the ice finally caused it to flow slowly outward, mainly to the south. Rocks and surface materials of all types were picked up and carried by the glaciers for great distances before being deposited. Pieces of granite, quartzite, and native copper among the many local rocks and minerals are found in glacial deposits and indicate that at least part of these deposits came from the Great Lakes Region. The materials deposited range from clay-size minerals to large boulders. - Woolly mammoth
Scattered mammoth and mastodon remains have been found in glacial deposits at various localities in the state. Peat, which is an accumulation of partially decomposed plant materials, has been found, especially in the northern part of the state. It is marketed as an organic soil conditioner. - Reconstruction of coal-forming swamp
Coal is a combustible rock that was formed by the accumulation and partial decay of vegetation. When coal was forming millions of years ago, most of the state was a low coastal plain bordered on the west and southwest by a shallow sea. A large variety of plants grew in great swamps which covered this coastal plain. When the plants died, they accumulated in the swamps to form thick masses of peat that were eventually covered by shallow seas and buried beneath mud and sand. Periodically, the region was above sea level, new swamps developed, new peat deposits accumulated, and more sediments were laid down. This process occurred repeatedly until over 3,000 feet of sediments had been deposited. Then the sediments were slowly compacted and hardened so that sandstones, shales, limestones, and coals were formed.