News Release, Kansas Geological Survey, March 19, 2008
LAWRENCE--A newly revised, full-color map of Kansas surface geology featuring a three-dimensional quality to distinguish hills from flatlands is now available from the Kansas Geological Survey, based at the University of Kansas.
"Geologic maps are some of the most important and basic products the Survey generates," Survey geologist Robert Sawin said. "This map, for example, provides information that will help Kansans make informed decisions about land-use and energy, aggregate, and water resources."
Drawn in full-color to differentiate the many rock layers found throughout Kansas, the computer-generated map depicts the age and type of bedrock at or near the surface.
"This map shows the rocks that would be exposed if you could remove all the soil and vegetation," said Sawin. "Also shown are larger areas of unconsolidated material, such a sand and gravel along rivers, and glacial deposits."
From east to west, as the map shows, bedrock in the state tends to get progressively younger. Expanses of Pennsylvanian- and Permian-age bedrock in the east, which were once covered by younger rock that have since eroded away, are about 270 to 300 million years old. More recent deposits from the Cretaceous Era found in the Smoky Hills of north-central Kansas are about 65 to 145 million years old.
West into the High Plains, the Cretaceous-age rocks have been mostly buried under even younger deposits that include sediment carried in by wind or water following the formation of the Rocky Mountains.
An exception to the rule that surface rocks in eastern Kansas are older than in the west is seen in the northeast corner of the map, where relatively recent glacial material is widespread and blankets the older bedrock.
Shaded relief, added for the first time to give the map its three-dimensional look, accentuates the different landscapes across the state, from the rolling glaciated region and Flint Hills in the east to the broad Arkansas River valley and High Plains further west.
In addition to rock units and relief, the map includes county lines, county seats, state and federal highways, streams, rivers, lakes, and a line marking the extent of glaciation.
First published in 1937 and last revised in 1991, the state geologic map is updated periodically to incorporate new geologic information and up-to-date rock classifications. This new 2008 revision includes a shift in the boundary between the Pennsylvanian and Permian bedrock, which was recently redefined by the geologic community.
The map is drawn at a scale of 1:500,000 so that one inch on the map equals about 8 miles of actual distance. Besides the map, the 68" x 39" sheet contains a graphically illustrated rock column, which classifies each rock unit on the map, and a generalized cross section.
The cross section depicts a slice of surface and subsurface rocks along a line from the Colorado border at Wallace County, near where the state's elevation peaks at just over 4,000 feet, to Johnson County and Kansas City, where the elevation is around 800 feet. As the bedrock become younger toward the west, the cross section illustrates, the state also increases in elevation.
Copies of the Surficial Geology of Kansas map are available from the Kansas Geological Survey, 1930 Constant Ave., Lawrence, KS 66047-3724 (or phone 785-864-3965) and at 4150 Monroe Street, Wichita, Kansas, 67209, 316-943-2343. The cost is $30, plus $5 for handling and postage. Kansas residents should call for the sales tax amount to be included. More information about the map and other KGS products is available at the Survey's web site (www.kgs.ku.edu).