how are prairies formed
Midwest prairies were formed relatively recently in geologic time. About 18,000 years ago much of the Midwest was covered by glaciers.As the glaciers moved through the area, their massive weight and grinding action flattened the soil.When the glaciers receded about 10,000-12,000 years ago, the huge amounts of melting water helped form river valleys.The melting waters also carried large amounts of soil and rocks. These were deposited as they receded.hen the glaciers receded about 10,000-12,000 years ago, the huge amounts of melting water helped form river valleys. The melting waters also carried large amounts of soil and rocks. These were deposited as they receded.