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Almost anywhere you dig in Illinois, you’ll find rich soil. Much of this soil has clay minerals called illite.
These minerals make the soil great for farming. That’s why Illinois is an important part of the Corn Belt. Farming is still a big part of Illinois’s money-making, especially corn and soybeans. The land has rolling hills, prairies, and rivers. Most of these were made by glaciers during the ice age.
◀ The last ice age ended 10,000 years ago. Before then, glaciers covered most of Illinois. Glaciers are huge masses of ice that move slowly across land. They covered most of Canada and much of the northern United States. As glaciers moved, they changed the land beneath them. In Illinois, they made paths that became our rivers and Lake Michigan. In other places, they made the land flat, and this became prairie.
Illinois is called the Prairie State because of the Central Plains. This huge area of flat land covers most of the state. The soil here has sand, clay, silt, and rocks left by melting glaciers. (Silt is tiny bits of rock that make soil rich.) This makes Illinois perfect for growing crops like corn. ▶
▲ Like the Driftless Area, Shawnee Hills in southern Illinois wasn’t touched by glaciers. It has lots of forests and rough land. Little Grand Canyon in Shawnee National Forest is here. You’ll see cliffs made of sandstone, caves, rock shapes, and clear lakes filled by spring water.
◀ South of Shawnee Hills are the Southern Illinois Lowlands. Long ago, this area was covered by the Gulf of Mexico. Much of it is swampy forest. Here, you’ll find plants and animals that don’t live anywhere else in Illinois. The state’s lowest point is here, just 279 feet above sea level.
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▲ Water makes up much of Illinois’s borders. The Mississippi River makes the western border and flows south for almost 600 miles. It meets the Ohio River, which makes the southern border. The Wabash River makes the southeastern border, while Lake Michigan makes the northeastern edge. The Illinois River (above) flows only within the state.
