The North American prairie lands were formed by the uplift of the Rocky Mountains, creating a rain shadow that resulted in lower precipitation downwind. During the last glacial advance (about 110,000 years ago) and retreat (about 10,000 years ago) most of the material for the prairies was deposited and the terrain leveled.
The tallgrass prairie, one of the most biologically diverse ecosystems in the world, still blanketed our state and much of the Midwest up until just under 200 years ago. Expansive seas of grasses and wildflowers in a mosaic of colors and textures competed for nutrients, water, and sunlight…with some plants growing taller than a horse and rider. Not a single tree was recorded on original land survey maps in some Iowa counties.
This diverse ecosystem once covered 170 million acres of North America and 14 states in the Midwest, including more than 80% of Iowa.