News Release, Kansas Geological Survey, Aug. 22, 2016
LAWRENCE--A new full-color geologic map of Morris County, an area mantled with marine rocks and fossils characteristic of the Flint Hills, is available from the Kansas Geological Survey based at the University of Kansas.
Mapped by KGS geologist Robert Sawin and Kansas State University professor emeritus Ronald West, the Morris County map highlights the type and age of rock layers and thick deposits of silt and other unconsolidated sediments found on the surface or immediately below the vegetation and soil. Shaded relief provides a three-dimensional quality that accentuates the hills and valleys.
Morris County lies almost exclusively within the Flint Hills region, which encompasses nearly 10,000 square miles of east-central Kansas and stretches from north of Manhattan to the Oklahoma state line. Nodules of chert, also called flint, are embedded in several of the local limestone layers and give the region its name.
Alternating layers of limestone and varicolored shale and other mudrocks at or near the surface in the Flint Hills were formed from sediments deposited in shallow seas rising and receding across the area nearly 300 million years ago during the Permian Period. Only the far southeastern corner of Morris County--where Permian rocks are missing and older Carboniferous rocks are nearest the surface--lies outside the Flint Hills region.
Although land is cultivated in stream valleys and a few upland areas with thicker soils, about 57% of the county is still covered with native grassland used mainly for grazing cattle and other livestock. The extensive limestone resources in Morris County are used as building stone, road material, riprap, and in concrete and agricultural lime.
The rock layering in the county is revealed in hilltop outcrops and road cuts where once long-buried rocks have been exposed.
"One of the most recognizable layers is a prominent light-gray ledge known as the Fort Riley rimrock that often has springs along its base," Sawin said. "About three-to-six feet thick, the rimrock is near the bottom of the Fort Riley Limestone Member and contains vertical fossilized bivalve burrows."
Fossils found throughout several of the limestone and mudrock layers are mainly Permian-age marine invertebrate animals, including clams, brachiopods, bryozoans, and one-celled fusulinids.
Stream valleys in the county are lined with more-recent layers of sand, silt, and other sediment worn off older rocks and transported by water. The headwaters of the Neosho River, an important source of water for downstream residents of southeastern Kansas, are in north-central Morris County.
"Previously unmapped sinkholes and faults at the surface shown on the map are evidence of the underlying Nemaha uplift, an ancient buried ridge adjacent to a fault zone that enters Morris County on the south-central border and trends northeasterly." Sawin said.
Upward displacement of subsurface rocks between two fault lines can be seen in a cross section on the map sheet. The cross section illustrates a vertical slice of subsurface rocks along a line running across the county nearly parallel to U.S. Highway 56.
Besides the map and cross section, the 68" x 42" sheet contains an illustrated rock column showing the order rock units were deposited over time and a description of each unit. The map includes towns, roads (from highways to unimproved roadways), elevation contours at 20-foot intervals, and township and range boundaries. The map scale is 1:50,000, so that one inch on the map equals about 3/4 mile of actual distance.
Copies of the Morris County map are available from the Kansas Geological Survey at 1930 Constant Ave., Lawrence, KS 66047-3724 (phone 785-864-3965, email pubsales@kgs.ku.edu) and at 4150 W. Monroe St., Wichita, KS 67209-2640 (phone 316-943-2343, email wwsl@kgs.ku.edu).
The cost is $15 plus shipping and handling. Inquire about shipping and handling charges and, for Kansas residents, sales tax. More information about county geologic maps and other KGS products is available at the Survey's web site (www.kgs.ku.edu). The map can also be accessed online at http://www.kgs.ku.edu/General/Geology/index.html.