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News Release, Kansas Geological Survey, July 27, 1998

Great Bend Sand Prairie Book Released

LAWRENCE--Sand dunes in south-central Kansas formed within the last 1,000 years, much more recently than previously thought. That means the land where the dunes are located is susceptible to even small changes in climate, according to a new book published by the Kansas Geological Survey, based at the University of Kansas.

The book demonstrates that dunes on the Great Bend Sand Prairie formed in the last 1,000 years during extended periods of drought in a climate very similar to today's. "If sand was blowing around significantly during the last 1,000 years, it wouldn't take much of a climate shift to start it moving again," said the book's author, Alan Arbogast, a geographer at Michigan State University and former KU geography graduate student.

The Great Bend Sand Prairie lies south of the bend in the Arkansas River and covers 1,100 square miles in Stafford, Barton, Edwards, Kiowa, Pratt, Reno, and Rice counties.

Prior to this study, dunes on the Great Bend Sand Prairie were thought to have formed more than 10,000 years ago, during a time of glaciation to the north in places like Wisconsin, when the climate was much cooler and dryer. Instead, radiocarbon dating of organic materials in the sand and silt shows that the region was probably an extensive wetland during the last Ice Age and that the modern landscape is really quite young.

"These dunes are extremely sensitive to minor fluctuations in temperature and precipitation," said Arbogast. "The only thing holding them together are the roots of prairie grass."

Although recent droughts--the 1930's Dust Bowl and a prolonged drought in the 1950's--caused the dunes to lose some of their vegetation, the destabilization wasn't significant, said Arbogast. The prehistoric droughts that caused the dunes to form must have lasted longer or been more intense.

According to Arbogast, sand probably blew out of the Arkansas River as a result of prevailing northwesterly winds.

To investigate the history and structure of these Kansas dunes, some of which are 30 to 40 feet high, Arbogast hired a backhoe operator to excavate trenches at 19 sites. Various laboratory tests were conducted on samples to find out the physical and chemical composition of the soil. Radiocarbon testing provided the ages of all the sediments, including the dunes.

The book, "Late Quaternary Paleoenvironments and Landscape Evolution on the Great Bend Sand Prairie," has many photos and line drawings, including a detailed map of the surface deposits in the Great Bend Sand Prairie.

The study, funded by a NASA Global Climate Change Fellowship, took Arbogast four years to complete, with three summer seasons in the field.

Similar studies have been conducted on sand dunes in Nebraska, Colorado, and Texas, but this is the first detailed study based in Kansas.

Copies of the book are available from the Kansas Geological Survey's Well Sample Library (316-943-2343) at 4150 Monroe in Wichita. The cost is $12.50, which includes sales tax, shipping, and handling. Copies are also available from the Survey's Lawrence office (at 785-864-3965).

A short extract from this publication is available.
Story by Liz Brosius, (785) 864-3965

Kansas Geological Survey, Publications and Public Affairs