An American Treasure

An American Treasure. Iowa's Loess Hills. Crushed by glaciers, carried by the wind, carved by rain, and inhabited by rare and unusual plants and animals, the Loess Hills of western Iowa possess natural features rarely duplicated anywhere else in the world. Only western Iowa and the Yellow River valley in China can boast of towering dunes of loess soil more than 200 feet deep. Iowa's Loess Hills extend in a narrow two to ten mile wide band that skirts the Missouri River valley along Iowa's western border. The steep, sharp-featured landscape, with irregular peaks, saddles and distinctive "catstep" terraces, is the product of tens of thousands of years of deposition and erosion. The rugged landscape and strong local contrasts in climate and soil conditions provide a desert-like habitat for a number of rare and unusual native plant and animal communities, many of which can be found in Iowa only in the Loess Hills., The Iowa Loess Hills are composed of sediments originally created by the grinding action of glaciers and wind deposited into dunes along the east edge of the Missouri River valley. As the climate warmed, these dunes were gradually stabilized by vegetation, a progression of coniferous forest to deciduous forest to prairie. Erosion continued to shape the hills. Native Americans had little environmental impact on the region, but after European cultures arrived in the 19th century, farming practices suppressed the natural wildfires that supported the prairie's dominance, thus allowing trees to once again encroach upon the hillsides and giving the hills their present appearance., Loess Hills Scenic Byway , The Loess Hills Scenic Byway is a system of signed roads through the Loess Hills region of western Iowa. The Byway's main route consists of 220 miles of paved road. Travelers can also follow any of the Byway's 15 excursion routes. The Scenic Byway is easily accessible from Interstates 29 and 80. The Byway links the most spectacular scenic areas in the Loess Hills as well as many historic, natural, and recreational attractions. More information about the Scenic Byway is available at area welcome centers., Geologic Wonder , The Loess Hills are a product of the Illinoian and Wisconsinan glacial periods when huge quantities of wind-blown silt, or loess, accumulated to heights of over 200 feet. Most of the loess deposits occurred between 18,000 and 150,000 years ago. The silt particles that form the Loess Hills were produced by the grinding movement of glaciers on rock underneath. Glacial meltwater carried the silt downriver during the summer. In the winter, water flow slowed and the silt was deposited on the flood plain only to be picked up by strong winds and deposited again along the eastern edge of the Missouri River. Erosion of the loess soil during thousands of years has helped form this unique landscape.