Geomorphic Assessment of Cheyenne Bottoms

by

Daniel Call


This webpage was created to satisfy requirements for the course Field Geomorphology for the fall of 2009 at Emporia State University.

Table of Contents


Introduction


State image acquired from the DASC website(www.kansasgis.org) and modified by Call (2009)

Cheyenne Bottoms is a 64 square mile (166 square kilometer) natural land sink located just northeast of Great Bend in Barton county, located in central Kansas. (Aber, Wetlands) Within this region lies the Cheyenne Bottoms Wildlife Area, a 19,000 acre (~7,700 hectares) nature preserve. Cheyenne Bottoms is a unique geologic feature, as it is an extraordinarily large depression. Its sheer immensity inhibits the ability of geologists to describe just how the structure could have formed. Explanations have ranged from the exogenetic (bolide impacts, eolian deposition, etc.) to the endogenetic (subsurface salt dissolution, faulting, etc.). This report is an attempt to analyze and interpret the data on the subject of the formation of Cheyenne Bottoms.

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Surficial Geology


This image represents the surface geology of the region. Data was acquired from the DASC website and modified by Call (2009).

Surficially, Cheyenne Bottoms is surrounded on 3 of its 4 sides by two types of bedrock. The Dakota formation is prominent along its western and southwestern margins while to the northeast, it is interspersed with Greenhorn Limestone and Graneros Shale. Along its southeastern flank, Cheyenne Bottoms faces a large loess deposit while sand dunes lie to the east of Cheyenne Bottoms. Within these boundaries, the floor of Cheyenne Bottoms itself is primarily composed of post-Kansan alluvial deposits.

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Local Water Sources


The Arkansas River is situated roughly 4 miles (6 km) to the south of the depression. There are two primary drainage sources into Cheyenne Bottoms. Deception Creek, which enters Cheyenne from the northwest, trends generally southeast. Blood Creek, the secondary source of water into the environment, makes its way in from the west-northwest and moves generally east-southeast. Walnut Creek is also a major water body in the region, as recent efforts to manage the wetlands have resulted in the construction of dikes and other water regulating structures to redirect water from Walnut Creek into the Bottoms region.

The water table moves from the west and southwest towards the northeast in this general region. In Cheyenne Bottoms, the average gradient is, in some places, as little as 2 ft/mile (0.38 m/km) which is well below the typical water gradient in the area. Adding to this hydrologic situation is the presence of the sand dunes on the southeast portion of Cheyenne Bottoms. This sand formation absorbs water quickly, building up a large reservoir of water that moves south into Cheyenne Creek and southwest into the Bottoms region as well. Structurally, a broad trough has formed beneath the Bottoms which is greatly similar to the underlying bedrock structure. This structure funnels water to the southeast where it reaches a restricted portion of the trough which is coincident upon a deep bedrock channel already present.(KGS Barton)

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Paleoclimate and Formation

During the late-Wisconsin period, temperatures were cooler, precipitation was higher and there was less seasonality than during the current climate regime. This is evidenced by the discovery of sufficient quantities of spruce pollen in the sedimentary record to suggest that Cheyenne Bottoms was a heavily wooded area (Arbogast, 1998). Added precipitation and the location of fluvial deposits suggest that the region that we know of as Cheyenne Bottoms today, was a region characterized by stream deposition and marginally strong running waters. However, this trend of running water changed by the late Pleistocene. Stream capture of the headwaters moving into Cheyenne by the Smoky Hill River dried up incoming sources of water. Adding to this stream capture was a climate shift from one of cool, humid conditions of the Wisconsin to one of warmer, drier conditions characteristic of the late Holocene.

By comparing regional eolian sand, Arbogast and Muhs (2000) were able to show that the prevailing wind direction during the late Wisconsin period was from the northwest as evidenced by the composition of sands in the area. These sands are more consistent with northeastern Colorado than those to the south of Cheyenne Bottoms, suggesting the dominant wind direction during this period was from the northwest trending to the southeast. These winds had shifted to a southwest to northeast pattern in the late Holocene with the associated climate shift. Due to these changes, terrestrial sands and loess began to accumulate across the southeastern portion of the area. This sand and loess originated from the southwest and was picked up and carried to this location by the newly dominant southwesterly winds. (see above) With this blockage in place, water has been effectively hindered from leaving the Bottoms. Cheyenne Bottoms is now a localized area marked by its relative slow discharge rate, relative to the rest of the geologic region.

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Subsurface Geology

Surface

This image is a Digital Elevation Model (DEM) of the region and was obtained through DASC. It has been modified to fit the following series of maps that are relevant to the area by Call (2009). The color gradient goes from green to red, with green representing higher relative elevation red representing lower elevation. Contour lines have been drawn to help line up this image with others to identify the relative location of the basin in the following images.

Bedrock

This image shows the general bedrock surface and dip trends across the area. Bedrock outcrops from the Dakota Formation bound the depression on all sides with the exception being the southeast lip. These are all represented by the topographic highs on the map. The dip across the region is typically from the Northwest to the Southeast at a rate of about 7 ft/mile (1.25 m/km). This formation is late Cretaceous in age. (Image and data from Bayne, 1976)

Stone Corral Formation

This image shows the surface of the Stone Corral formation. Contrary to the bedrock surface, the Stone Corral dips from southeast to northwest at a rate ofabout 9 ft/mile (1.7m/km). A basin with 20 ft (6 m) of closure lies in nearly the same location as the central portion of the deeper end of Cheyenne. This map Stone Corral Formation is situated at approximately 1550 ft (472 m) above sea level and is up to 800 ft (243 m) thick down to the top of the Hutchinson salt. The Stone Corral is Permian in age. (Bayne, 1976)

Top of Hutchinson Salt

Similar to the Stone Corral, the top of the Hutchinson Salt layer slopes from east to west at a rate of about 9 ft/mile (1.7m/km) A side note of interest on this map is that there were few drillings performed in Cheyenne Bottoms. Additional drilling may alter the contour lines substantially in this area. This level is roughly 680 ft (~207m) above sea level. The Hutchinson Salt is Permian in age, roughly 245 million years old.(Bayne, 1976)

Base of the Hutchinson Salt

The same general structural features that are present on underlying rock layers and the overlying salt beds are present in the base of the Hutchinson Salt bed. This level is roughly 400 ft (122 m) above sea level.(Bayne, 1976)

Winfield Limestone

The Winfield limestone dips from east to west fairly consistently across the region with the basin like region in the center of the Bottoms being more pronounced than in upper Hutchinson salt layers. Roughly 160 ft (~49 m) above sea level. (Bayne, 1976) The Winfield is Permian in Age.

Heebner Shale

Similar features occur in this layer that have occurred in younger layers to this point. Dip appears to be from the northeast to the southwest for the most part across this region with a new basin-like feature prominent southwest of the Bottoms region. Depth is now at close to 1160 ft (~354 m) below sea level.(Bayne, 1976) The Heebner Shale is Upper Pennsylvanian in age.

Precambrian Surface

The Precambrian surface shows a distinguishable trench or valley, trending from the northwest portion of the study area to the southeast. Several hill-like structures make an appearance in this layer situated at locations that ring the surface perimeter of Cheyenne Bottoms. The dip between these hills is distinctly southeast, which coincides with the direction of typical water flow and topographic relief for the region at large. It is roughly 2,000 ft (610 m) below sea level. (Bayne, 1976) Similar ellipses, albeit of a much smaller magnitude, occur in Sedgwick and Finney counties, which may suggest a Precambrian structural trend in the west-central to western portion of Kansas.(Harbaugh and Merriam)

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Wildlife, Vegetation and Anthropogenic Usage

These photos were taken on the northeast rim of Cheyenne Bottoms and put into a mosaic by Call (2009).

Wildlife and Vegetation

Cheyenne Bottoms has always been a region of great ecological importance. Its location within the Great American Flyway makes it a prime rest stop for waterfowl of all kinds. This was recognized as far back as Pre-Settlement times, as the Cheyenne Indian tribe was known to fight many battles to protect their claim of the territory for hunting grounds. (About Cheyenne) The vegetation and generally moist conditions allow many wetland plants to thrive, most notably, bulrush and spikesedge. Since the 1960s cattail has managed to take root and successfully grow to dominate the area. These plants have enabled a whole host of assorted lifeforms to blossom. Muskrats use cattail roots as a source of food, and the plant remnants as a source of material for building shelters. Bloodworms feed upon the the bacteria that, in turn, feed upon the decomposing organic material. The large bloodworm population provides the primary staple for shorebird diets and is reflected by the sizable bird population that visits Cheyenne Bottoms during spring and fall migrations. (Aber) The sheer diversity and abundance of water fowl, approximately 350 different species and 45% of all North American migrating waterfowl, has contributed to making Cheyenne a Wetland of International Importance by the Ramsar Convention. (About Cheyenne)

Anthropogenic Usage

As stated in the previous section, Cheyenne Bottoms was used as prime hunting ground by Native American tribes. Man's use of the region has drastically changed throughout time. In 1896, the Grand Lake Reservoir company was formed to divert water from the Arkansas River into Cheyenne bottoms for two purposes. This water was to be used to generate electricity, to develop the region to form a recreation and resort area, and to provide water for extensive irrigation and agricultural use. The company went broke and disbanded in 1903, yet ideas for using the region had not ceased. From 1945-46, the area was leased to the United States Army Air Corps as a bombing and target range. As to be expected from such activities, wildlife was devastated by this activity and the military ceased using Cheyenne as a bombing and target range. Federal money generated from the Pittman-Roberston Act of 1937 helped the Kansas Forestry, Fish and Game Commission to begin purchasing and developing the southeast portion of Cheyenne Bottoms. Part of this area was finally opened to public hunting by 1952.

In the 1990s, in response to fluctuating water availability concerns from park managers, the Kansas Department of Wildlife and Parks began a substantial renovation effort aimed at increasing the ability to manage water flow by dividing the preexisting pools in such a way as to limit water lost due to evaporation. The Nature Conservancy joined their efforts in protecting the Bottoms as well by purchasing and managing 7,300 acres (~3,000 hectares) adjacent to the Cheyenne Bottoms Wildlife Area. Thanks to these efforts, Cheyenne Bottoms is famous around the world as a prime location for hunting and birdwatching in the Midwestern U.S. (About Cheyenne).

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References

About Cheyenne Bottoms accessed online at http://www.cheyennebottoms.net/about_cheyenne_bottoms.html Accessed December 8, 2009.

Aber, J. S., 2005. Cheyenne Bottoms, Kansas. http://academic.emporia.edu/aberjame/wetland/chey_bot/cheyenne.htm, Accessed November 5, 2009.

Arbogast, A.F., and Johnson, W.C., (1998) Late-Quaternary Landscape Response to Environmental Change in South-Central Kansas, in Annals of the Association of American Geographers, Vol. 88, No.1, p. 126-145

Arbogast, A.F., and Muhs, D.R., (2000) Geochemical and mineralogical evidence from eolian sediments for northwesterly mid-Holocene paleowinds, central Kansas, USA. in Quaternary International 67 (2000) p.107-118

Bayne, C.K., (1977) Geology and Structure of Cheyenne Bottoms, Barton County, Kansas, in Kansas Geological Survey, Bulletin 211, Part 2. Online version Accessed Oct. 31 at http://www.kgs.ku.edu/General/Geology/Barton/07_gw.html

Fent, O.S., (1950) Pleistocene Drainage History of Central Kansas, in Transactions of the Kansas Academy of Science Vol. 53 No.1 pp.81-90

Harbaugh, J.W., and Merriam, D.F., (2008) Topographic ellipses in Finney and Sedgwick counties, Kansas may signal deep structures in Precambrian basement in Transactions of the Kansas Academy of Science Vol. 111, no 3/4 p. 269-274

Journey through the Wetlands accessed online at http://www.visitgreatbend.com/pdf/Journey_thru_wetlands.pdf on December 8, 2009

KGS -- Barton and Stafford County Geohydrology at http://www.kgs.ku.edu/General/Geology/Barton/07_gw2.html, accessed Nov. 11th

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