Geology of the Loess Hills, Iowa

Information Handout



Many Americans think of Iowa as having little topographic variation. However, in westernmost Iowa the Loess Hills rise 200 feet above the flat plains forming a narrow band running north-south 200 miles along the Missouri River. The steep angles and sharp bluffs on the western side of the Loess Hills are in sharp contrast to the flat rectangular cropfields of the Missouri River flood plain. From the east, gently rolling hills blend into steep ridges.

Loess (pronounced "luss"), is German for loose or crumbly. It is a gritty, lightweight, porous material composed of tightly packed grains of quartz, feldspar, mica, and other minerals. Loess is the source of most of our Nation's rich agricultural soils and is common in the U.S. and around the world. However, Iowa's Loess Hills are unusual because the layers of loess are extraordinarily thick, as much as 200 feet in some places. The extreme thickness of the loess layers and the intricately carved terrain of the Loess Hills make them a rare geologic feature. Shaanxi, China, is the only other location where loess layers are as deep and extensive. Though much older (2.5 million years) and much thicker (nearly 300 feet) than Iowa's loess, the Shaanxi loess hills have been greatly altered by both natural and human activity and no longer retain their original characteristics.

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Publication type Report
Publication Subtype USGS Unnumbered Series
Title Geology of the Loess Hills, Iowa
Series title Information Handout
DOI 10.3133/70220361
Year Published 1999
Language English
Publisher U.S. Geological Survey
Description HTML Document
Country United States
State Iowa
Other Geospatial Loess Hills
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