The Kansas landscape was formed by alternating periods of deposition and erosion. Various ecoregions are defined by their consilient properties to form species range boundaries. Each ecoregion is different, and that difference is determined largely by geology, soils, and climate.

The Ozark Plateau in extreme southeastern Kansas is made up of rocks deposited during the Mississippian Period of geologic history, about 350 million years ago. Landforms in the Ozark Border, Osage Plains and the Cross Timbers are all Pennslyvanian in age, deposited about 300 million years ago. The Flint Hills of east-central Kansas and the Red Hills in the south-central part of the state are both Permian in age, roughly 250 million years old.

Cretaceous-age rocks, deposited about 100 million years ago during the time of the dinosaurs, form the landscape in the Smoky Hills. The Western Plains and Cimarron Plains of western Kansas are composed of rock debris washed off the face of the Rocky Mountains over the past few million years. The Arkansas River Sandsage Prairie and Arkansas River Sand Prairie are areas of recent deposition that border rivers. Glaciers moved into Kansas about 750,000 years ago and sculpted the northeastern corner of the state.