Describing The Loess Hills
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Along the shores of the Missouri River you'll discover historical natural wonders in the unique and beautiful Loess Hills (pronounced "luss"). The Loess Hills are truly a unique, world class landform. The Indians often used the word "sacred" when describing the Loess Hills. To the Indians, sacred meant that an area was so special that no tribe or group of people could control it. Unfortunately, the white man does not have that perspective. Over 95% of these Hills are owned by private individuals. Our challenge is to impress not only the tourists, but also these private landowners, with the beauty and the uniqueness of these Loess Hills, as well as their value from a biological point of view. A virgin prairie can never be reproduced. It would take only a few gallons of chemicals to destroy what has taken nature thousands of years to create. It should be our goal to preserve the Hills in as close to a natural state as possible, while yet realizing that the land must provide a living for the landowners. The Loess Hills belong to us and we should be proud of them. They truly are a gift to us from God. |
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There are only two formations of loess with these extreme depths in the world: in western Iowa and in China. One major difference between China and Iowa's Loess Hills is the origin of the silt. In China, the silt was blown in from a desert, whereas in Iowa, it originated from the Missouri River flood plain. The loess hills in China have been altered and no longer retain any of the natural characteristics.
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Loess is a geological term, of German derivation, meaning loose or crumbly. In the geological sense, loess means windblown soil. It is true that loess is found throughout the United States and Iowa, but not in the depths that we find here in the Loess Hills, where the loess formations sometimes exceed 200 feet. The Loess Hills were formed between 14,000 and 24,000 years ago. During this time, the glaciers were very active and covered a large portion of the northern United States, including northern Iowa. |
In the summer, the warm air would melt the glaciers creating tremendous flows of water down each river valley, particularly the Missouri River valley. When the weather became cold during winter, the glaciers stopped melting, exposing huge mud flats. Strong winds sorted the exposed sediments and swept the finer materials off of the flood plain into huge clouds of dust, depositing them in the bluffs we now have today. The majority of this silt was deposited on Iowa's side due to the dominant westerly winds. As this silt accumulated, the bluffs were formed. The coarser silt was deposited close to the riverbed, which formed the sharply angled and high-ridged bluffs along the western edge. As you travel farther east, the bluffs become less sharp, more rolling and considerably lower in height.