News Release, Kansas Geological Survey, April 26, 2004
LAWRENCE--New full-color maps of the geology at the surface of two counties in southwestern Kansas are now available from the Kansas Geological Survey, based at the University of Kansas.
The maps of Hamilton County and Kearny County are by William Johnson, professor of geography at KU.
The new maps show the age and type of rocks at the surface of Hamilton and Kearny counties, along with other features, such as rivers, lakes, quarries, roads, railroads, landing strips, and irrigation ditches.
Because geologic maps show the rock formations likely to be encountered in a given location, they are useful in construction, in understanding soils and agriculture, in searching for water and mineral deposits, and in a variety of engineering and environmental uses.
The new maps show that much of the surface in these two counties is covered by sands, soils, and other materials deposited within the past few million years. An extensive area south of the Arkansas River, for example, is covered with sand dunes--most of them stabilized, but a few of them still active--that were deposited by the wind.
On the north side of the river is an area where the Ogallala Formation, composed mainly of sand and gravel, is exposed. The Ogallala is the source of much of the groundwater that is used for irrigation in the western third of the state.
In a few places along the Arkansas River, much older rocks are shown on the maps. These rocks were deposited during the Cretaceous Period, about 80 million years ago, and have been exposed by the erosive power of the river.
The maps also show the Bear Creek Fault, a subsurface fault that runs beneath parts of both counties. And it depicts a number of playas, or shallow depressions at the land's surface that often retain water following heavy rains.
Each map covers one county and is drawn at a scale of 1:50,000, so that one inch on the map equals about 3/4 mile of actual distance. It measures about 48 inches by 32 inches.
Copies of the new maps are available from the Kansas Geological Survey, 1930 Constant Ave., Lawrence, KS 66047-3726 (or phone 785-864-3965). The cost is $15.00, plus $4.00 for handling and postage. Kansas residents should add 7.3% sales tax on the cost of the entire order. More information about the maps and other KGS products is available at the Survey's web site (www.kgs.ku.edu).