Loess Hills
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The Loess Hills is a formation of wind-deposited loess soil in the westernmost part of Iowa. They are generally located from between 1 and 15 miles to the east of the Missouri River channel. These hills are the first rise in land beyond the flood plain, forming something of a "front range" for Iowa. During the Ice Age, glaciers advanced into the middle of North America, grinding underlying rock into dust-like "glacial flour". As temperatures warmed, the glaciers retreated and vast amounts of meltwater and sediment flooded the Missouri River valley. The sediment was deposited on the flood plain, creating huge mud flats. When meltwaters receded, these mud flats were exposed. As they dried, the fine-grained silt was picked up by strong prevailing westerly winds. Huge dust clouds were moved and redeposited over broad areas. The heavier, coarser silt was deposited close to the Missouri River flood plain, forming sharp, high bluffs on the western margin of what became the Loess Hills. Today, these hills stretch from Sioux City in the north to the Missouri border in the south, and in to Kansas and Nebraska. The soil has a characteristic yellow hue. The Loess Hills of Iowa are remarkable for the depth of the drift layer, often more than ninety feet deep. The only comparable deposits of loess to such an extent are located in China. The Loess Hills have abundant bur oak and red cedar and some of the last remaining stands of prairie grass in the state. The areas of natural prairie are comprised of big bluestem and little bluestem, Indian grass, sideoats grama and forbs such as yucca, pasque flower and lead plant (false indigo). Fauna of the Loess Hills include white-tail deer, coyote, wild turkey, and ringneck pheasant. Historically, fauna also included American bison, prairie chicken, mule deer, elk, and gray wolf; these were extirpated by the late-nineteenth century.
There are numerous scenic drives, with county and state parks in the area. The Loess Hills State Forest is located in west-central Iowa in Harrison and Monona counties. It is comprised of 4 units totaling 10,600 acres, and offers hiking, backpacking, picnicking, and fishing opportunities.
Loess soil also forms the Arikaree Breaks in northwest Kansas, and the Mississippi-Yazoo "Bluff Hills" near Vicksburg, Mississippi.
External links
- [Loess Hills Scenic Byway]
- [Loess HIlls Western Iowa]
- [Geology USGS]
- [Fragile Giants]
- [Loess Hills State Forest]
- [Sen. Charles Grassley on the Loess Hills]
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