Huge continental glaciers, hundreds of feet thick, came from the north to northeastern Kansas in at least two different episodes, carrying rocks, gravel, sand, and a special clay called loess to the Blue Rapids area. Fertile soils and sand and gravel industries came from these glaciers. They bulldozed the previous soils, grasses, trees, and other plants, chilled the climate, lowered the Earth's sea level, then washed the landscape with meltwater and charged the atmosphere with more moisture for deluges of rain and snow. The surging water formed the present-day stream courses.