Why are these glacial deposits
so good for agriculture?
Glacial deposits of drift and loess are even textured, fine-grained, and free of rocks. They also retain moisture well. These soil characteristics enhance agriculture. In areas of Illinois that were not covered by glaciers, the bedrock is nearer the surface and the terrain is less flat. This makes agriculture more difficult.Early 1800s' European and Euro-American settlers to the southeastern part of the state were amazed at the fertility of the prairie soil. The soil pit image to the right shows loess (the top third) over Illinoian Glacier till. Note the absence of any rocks that would make plowing difficult.
John Woods, a settler on the English Prairie of the area of Albion, in southern Illinois, wrote a description of the soil in 1819, "The soil found in digging wells, is, first, a vegetable mould, next loamy clay, then sand-stone, and lastly clay-slate, through which no one has penetrated." He went on to speculate that coal lie under the clay because he has seen thin ribbons of coal near the surface in the area. The prairie he lived on was between the Little Wabash and Wabash Rivers in southeast Illinois.
The land north of the Shelbyville Moraine is richer because of the presence of more glacial till and loess. The farther south in Illinois, the more hills and forests exist. The same thing happens in the northwestern corner of the state. It requires more work to farm these areas, and farming is different that on prairie soil.
Activity: Read the narrative by William Oliver, a traveler in 1843 who wrote Eight Months in Illinois. He speculates on the origins of the soils that he saw in southern Illinois. Then write or 'tell' Mr. Oliver (from what you learned in this section on glaciers and soil) what really happened.