The Loess Hills are a rugged landform that extends in a narrow band (3-10 miles wide) along the Missouri River in western Iowa. These massive drifts of silt were deposited by windstorms carrying glacial material from the Missouri River valley during the Ice Ages. Following deposition, periods of erosion sculpted the hills into the picturesque bluffs, precipitous peaks, and rugged ridges that seem to spring up from nowhere out of the flat Missouri River floodplain. Within the Loess Hills can be found the majority of Iowa's remaining natural areas including remnant prairie and bur oak woodlands. These disappearing plant communities provide the last remaining habitat for many rare plant and animal species and invaluable ecosystem services including water and air quality for western Iowa.