"In no section of the Union, perhaps, are the effects of heavy rain more strikingly visible than in Illinois. The tenacious clay, which everywhere underlies the soil, prevents that free and speedy absorption of water which takes place in more sandy or stony regions. As a consequence, the water accumulates more rapidly, and causes a sudden rise in the creeks and branches. Our traveler found some difficulty in fording the streams and in more than one instance was obliged to swim with his horse. He observed that the water had a very thick and muddy appearance and at this he was not in the least surprised, on noticing how deeply the roads and ravines had been gullied out. When once the prairie sod has been broken, especially on a declivity, the process of erosion becomes extremely rapid; and the only method to prevent the formation of a deep ravine is to supply a new turf by sowing blue grass."

He continued to explain that once large marshlands were drained by ravines. Just one row of plowing could start a gully that soon swelled into a stream that drained the whole area.