Introduction to Earth Science
Virtual Field Trip

The Flint Hills and Chase County

We will turn north off of Highway 50 and leave the Cottonwood River floodplain. After one mile, it is obvious why there is a cluster of homes and a church! You can see the rise in the landscape as we climb up onto the Emporia Terrace and successively higher terraces, and into the Flint Hills. This is the Toledo Township and several homes belonged to the families who abandoned the town of Saffordville, which was located on the floodplain and suffered repeated flooding of the Cottonwood River. These homes do not flood but at times the people have a very long commute to work when their access to the south is underwater. Note the crops in the first one mile and then the change in land use as we get into the Flint Hills. To the right is a near vertical kite photo from Aber's KAP Gallery, http://www.geospectra.net/kite/gallery/cattle.htm, which shows erosional trails made by cattle in the Flint Hills. The fence line is fairly obvious also, just to the left of the road, where there is no grazing to the right of the fence!

Overview of Flint Hills in Chase County. The Crouse Limestone is visible in the foreground and the trees stand near a stream. The image was taken from J. Aber's Flint Hills guidebook. Photo by J. Aber, 6/99

Chase County was organized in 1859, with approximately 775 square miles. Cottonwood Falls is the county seat and the county's population is about 3,000. The county is in the Flint Hills physiographic province. The first settlers moving in and through the Flint Hills found the rocky soil too sparse and too hard to plow for cropland. Limestone and chert cap the hills, while less resistant shale form the slopes. Chert deposits were used to craft arrowheads and other devices, and help maintain the high topographic relief, as well as serving to give the hills their name. Flint and chert are the same material, microcrystalline quartz. Open range grassland once covered most of central and western Kansas as well as surrounding states. The Flint Hills region is famous for the Big Bluestem, a warm season grass, and is one of the last native prairie grasslands left in the U.S. Many scenes in Chase County look untouched for the last 10,000 years! What do you think is the dominant use of the land in the Flint Hills? Is there a difference between land use on the floodplains and terraces as opposed to the upland surfaces?

Land Use Land use is detailed in the map below, with the lighter green being grassland (86%), cropland in yellow (9%), and 4% woodland in the darker green. Blue is water and shades of pink, urban. For many years, the rich grasslands supported buffalo and antelope, although these animals are not easy to domesticate! Today cattle outnumber people, although some bison and deer may be found. The abundant, thick limestones in the county are a prime resource. Chase County limestone has been quarried since the 1870s and is found in the county courthouse in Cottonwood Falls, State Capitol Building in Topeka, buildings at Ft. Riley, The Eisenhower Library at Abilene, as well as structures in Chicago and San Francisco (Childs, et.al., 1988). The Chase County courthouse was completed in 1873, after two years of construction, at a total cost of $42,599.88. The Roniger Museum, dedicated in 1960, is located behind the courthouse and built of limestone. The museum houses a collection of Indian artifacts, stuffed animals and birds, hair wreaths and more! Figure to the right was taken from http://gisdasc.kgs.ukans.edu/kanview/landcov/html/Chase.html.

Surface and Groundwater

Chase County, small spring fed stream in an unburned pasture. Photo by S.W. Aber, 4/2000

The Flint Hills region receives ample rainfall, about 32 inches (80 cm) average annual precipitation. This water interacts with vegetation, soils and rock, which produce changes in water composition that affect water quality. The Flint Hills are, in general, a region of water surplus; water leaves the region via many surface streams and by subsurface migration. The Flint Hills are near the western edge of the United States' region of water surplus; western Kansas generally has a water deficit. The Flint Hills give rise to many perennial streams and rivers including the two that flow through Emporia, the Cottonwood and Neosho. Although many of these are spring fed, they tend to be flood prone. Flash floods may occur at any time of year, due to the combination of relatively impermeable soils and bedrock (shale) and potential for severe thunderstorms. Floods occur most often during the spring and early summer (April-July) with a second flood season in autumn (October-November).

The Army Corps of Engineers constructed a reservoir at Council Grove primarily for flood control, which has greatly reduced the downstream flooding of the Neosho River. However, most other streams within the Flint Hills remain unregulated. As an example, the Cottonwood River in Chase and Lyon counties experienced severe flooding in Oct. 1985, July 1993, May 1995, April 1997, and Nov. 1998. During such floods, significant erosion, transportation, and deposition of sediment takes place within stream channels and on flood plains.

Ground water is readily available throughout the Flint Hills region and the water migration is from east to west. Recharge takes place where aquifers outcrop to the east, and water moves down the regional bedrock dip toward the west. The bedrock aquifers are separated by thick, relatively impermeable shale units. Artesian wells are common in several parts of Marion and western Butler counties. The Flint Hills region has some 61 springs identified and, compared with springs elsewhere in Kansas, they have maintained their historic flow rates and high water quality (Buchanan, Sawain, and Lebsack, 2000). Springs are areas where water flows from the rock or soil onto the land without the influence of engineering. Water permeates buried porous limestones, but not the more impermeable shales, and springs flow out between the contact of these rock types.

Image taken from http://academic.emporia.edu/aberjame/field/flint/flint.htm. A porous limestone block of Ft. Riley Limestone. Photo by J. S. Aber, 7/90.

Florence (in the Flint Hills, just west of Chase County, in Marion County) boasts "99% pure spring water" for their drinking water. Their source, Crystal Spring, flows some 4,000 gallons per minute and is one of the largest single springs in the Flint Hills (Buchanan, et.al., 2000). The spring emerges near the base of the Barneston Limestone on the northern side of the Cottonwood River valley.

Permian Cyclothems

After turning west onto the gravel road, you will note rock layers that are exposed in the road. Looking out in the distance, stone lines, or limestone rock outcrops, are prominent especially after the spring burn. Note the unburned pasture in which no rock outcrops are visible! What time of the year would be best for a geologist to map the Flint Hills?

Burned pasture to the right of the road, unburned, left. Photo by S.W. Aber, 4/2000.

Burned pasture in the background, unburned area in the foreground is protected from fire by the flowing spring. Photo by S.W. Aber, 4/2000.

Much of the grass ecosystem in the Flint Hills is managed with fire. Spring burning brings back the lush vegetation, appreciated by cattle and bison and to rid the landscape of woody vegetation that would compete for water. How could you tell where a homestead once stood or the areas that are not burned? The Flint Hills support the largest area of native tallgrass prairie remaining in North America. Be sure to visit the Tall Grass Prairie Preserve and Z-Bar or Spring Hill Ranch house and barn (National Park Monument), located about 20 miles west of Emporia.

Three limestone formations are visible in the figure above, from top to bottom: Funston, Crouse, and Eiss. This is a kite aerial photograph and the kite line is visible in the image. Just above the prominent white road, the fence line is visible with more erosion on the grazed side (toward the top of the image). Image taken from http://www.geospectra.net/kite/gallery/flint.htm. For more kite photgraphy see Aber's KAP Gallery.

Lake Kahola

Lake Kahola is located 10 miles north of Highway 50 and straddles the Chase and Morris county line. The lake is fed by Kahola Creek, surface and spring waters. "Kahola" is derived from the Indian word meaning "spring water." It was initially built in the 1930s as a WPA project to serve as the water source for Emporia. Kahola Park was developed for recreational use as well and sixty summer cabins were built by 1944. There are some two hundred cabins now, several occupied year-round, and a full-time caretaker in residence and management by the Kahola Park Cabin Owners Association. Although Emporia still retains water rights to Kahola, Council Grove Reservior was built and took over as Emporia's water source via the Neosho River.

The image was taken from Aber's KAP Gallery, Lake Kahola, 7/99, http://www.geospectra.net/kite/kahola/kahola.htm

The history of Emporia's waterworks system is display above Kahola Lake. In 1879 a committee was appointed and a special election passed $50,000.00 in bonds for a waterworks to be built on the Cottonwood River. It was built in 1880 and abandoned in 1887!

Photo by S.W. Aber, 4/2000

The Neosho River was deemed more desirable and bonds, for $162,000.00, raised for the construction in 1886. The first dam, built in 1887, was raised two feet in 1901, and the waterworks completed in 1890. Electic pumps replaced steam pumps in 1911 and another dam and filtration plant constructed in 1916. Kahola was completed in 1936 and a water softening plant installed. The bronze history has a "signature" of W.A. White.

After examining the dam, hike down to the spillway for a good overview of the rock strata. The layer cake look of the Flint Hills is the result of Permian age cyclothems. A cyclothem is mainly a triad of three sedimentary rocks, limestone-shale-limestone, and represents mainly marine transgressional and regressional depositional environments. A likely explanation for the repeated marine transgressions and regressions of the Permian cyclothems in Kansas is a worldwide change in sea level related to glaciation in Gondwana, the theoretical ancient continent which included India, Australia, Antarctica, and parts of southern Africa and South America (J. Aber, 1991).

Major cyclothems are 50-100 feet (15-30 m) thick and include the Speiser/Wreford and Blue Springs/Barneston rock sequences as examples. Minor cyclothems are only 25-40 feet (8-12 m) thick and include the Eskridge/Beattie, Blue Rapids/Funston, Wymore/Kinney, and Gage/Winfield rock sequence examples. Water depth probably did not much exceed wave base during deposition of minor cyclothems.

Red sedimentary rocks of sandstones and shales (called red beds), cherty limestone, dolomite, and evaporites (subsurface salt, gypsum, anhydrite deposits) are the common rocks and minerals in Lower Permian strata. This strata is missing the black shales, that are common in Pennsylvanian age rock, which suggests that the deepest water conditions were not achieved during major marine transgressions during Permian time. The total range of relative sea-level change between exposed coastal lowland (6) and maximum transgression (2) was probably 100 feet (30 m) or less (McCrone 1964).

This repeated sequence of rock strata, or cyclothems, were identified by R. C. Moore (1964). One such systematic repetition of bedrock is found in the lower Permian rock of the Flint Hills, representing the change between a shallow sea and emerging coastal lowland. This cyclothem model explanation details the six typical units beginning at the top of the sequence (working from youngest rock, 1., to oldest rock, 6.).

• Limestone - The depositional environment at the top of the sequence is one of an offshore regressive sea, which grades into a shallow, high-salinity, lagoonal environment. This depositional environment is represented today by chalky to dolomitic limestone with diverse fossil remains. It is tan to gray in color, platy (parallel arrangement of rock layers) to massive in outcrop, and cross bedding, oolites, and ripple marks are common sedimentary structures. The limestone may contain chert at the base and algal remains toward the top. Some Lower Permian examples include the Morrill, Schroyer, Fort Riley, and Cresswell limestones.
• Shale - This depositional environment represents the maximum transgression of the shallow sea or an environment that would be the farthest offshore. The rock is a gray or green, fissile to platy, fossiliferous shale or shaly limestone with diverse fossils, including trilobites. Some Lower Permian examples include the Florena, Havensville, Oketo, and Grant shales.
• Cherty limestone - Next in the cyclothem sequence is the transgression from far offshore to a more shallow sea depositional environment. A tan or light gray, platy to massive, fossiliferous limestone or chalky limestone is the result. The limestone beds contain scarce to abundant nodules or beds of chert with diverse fossil remains including echinoids (sea urchins, sand dollars) and fusulinids (looks like wheat or rice grain). Lower Permian examples include the Cottonwood, Threemile, Florence, and Stovall limestones.
• Shale - The shale is repeated in the cyclothem, representing a shallow, normal salinity, transgressive sea environment. It is gray, tan or green, platy, fossiliferous, calcareous shale and shaly limestone. The fossil remains include clams and snails, abundant brachiopod and mollusk fossils. The examples include the upper Eskridge, upper Speiser, upper Wymore, upper Gage shales.
• Limestone - The limestone in this portion of the sequence was deposited in a shallow to estuarine (drainage channel adjacent to the sea effected by tides), low-salinty sea. The result is thin, gray or tan, chalky or coquina limestones with abundant brachiopods and mollusks. The examples are found as thin limestones found within the shale members of the middle Eskridge, middle Speiser, middle Wymore, and middle Gage.
• Shale - Last in the sequence of one cyclothem is a lagoon or estuarine (green or black) to an emergent tidal flat (maroon) depositional environment. The shale is platy, somewhat calcareous, maroon or red in color above green and black shale. There an absence of marine fossils in the maroon shales and a few inarticulate (lacking the hinge) brachiopod fossils in the black shale. The lower Eskridge, lower Speiser, lower Wymore, and lower Gage shales complete the cyclothem examples.

Image taken from http://academic.emporia.edu/aberjame/field/flint/flint.htm.
The waterfall area is formed by the "middle" limestone within the Eskridge Shale.
The massive blocks of the Cottonwood Limestone rest on top of the fall.
Photo date 10/81, © J.S. Aber.