News Release, Kansas Geological Survey, June 3, 2004
LAWRENCE--A new full-color map of the geology at the surface of Pottwatomie County is now available from the Kansas Geological Survey, based at the University of Kansas.
The map shows the age and type of rocks at the surface, along with other features, such as towns, 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 map shows that most of the bedrock in Pottawatomie County is Pennsylvanian or Permian in age, primarily limestones and shales deposited 250 to 300 million years ago. Several of the Permian limestones contain chert, or flint, which makes this area part of the Flint Hills region.
The map also shows glacial features, or places where glaciers moved into northeastern Kansas 600,000 years ago and left behind boulders, silt, and other material. For example, the map shows the location of several places where the melting glacier left behind the load of rock it was carrying.
In addition, the map shows the location of several subsurface features. These include faults and a buried mountain range called the Nemaha Ridge. Faults along the edge of the Nemaha Ridge have produced some of the largest earthquakes in Kansas history, including one near the Pottawatomie County town of Wamego in 1867 that would have registered about 5.5 on the Richter Scale, and was felt as far away as Dubuque, Iowa. Small earthquakes, many too small for people to feel, still occur regularly along the Nemaha.
The map 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 map 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).