The force of the moving ice was so strong, it broke large quartzite boulders off outcrops in South Dakota, Iowa, and Minnesota and carried them over 200 miles into Kansas. The boulders can still be seen scattered throughout the area today. The glaciers also left behind a layer of sediment. Finely ground silt, called loess, was sorted and carried by the wind. Thick layers of loess were deposited throughout the area.
Fertile soils formed from loess are good for farming because they contain few rocks.