PEAT
After the retreat of the last of the great ice sheets from Illinois, numerous ponds and lakes were left in northern Illinois, especially in the eastern section. Some of them were soon drained by natural processes, but others remained. In the shallow water along their shores grew various plants, chiefly reeds and sedges and, locally, a variety of moss. As the plants died, their partially decomposed remains were preserved beneath the water. Ultimately, the ponds and lakes were overgrown and more or less completely filled by the plants and their remains, giving rise to peat ([fig. 22]) bogs.
Some peat bogs have been drained and are now used as farm land. Others remain and a few of them are the source of peat or humus for horticultural purposes. Producing operations are located in northeastern Illinois and in Whiteside County in northwestern Illinois.