GEOLOGY

Contributor: Mike Driessen

GEOLOGY

    All the rocks exposed in Barton and Stafford Counties are of sedimentary origin and range in age from Cretaceous to Recent. The oldest Cretaceous rocks exposed at the surface are Lower Cretaceous (Comanchean) in age and comprise part of the Kiowa shale.  Quivira National Wildlife Refuge Geologic Map

SURFICIAL GEOMORPHOLOGY

              The area surrounding Quivira National Wildlife Refuge is composed mainly of sand dunes containing discrete and superimposed parabolic dunes; irregular dunes with high relief; undifferentiated, low relief sand sheets deposited by eolian, lacustrian and alluvial processes; and finally low terraces and floodplains.  All of the deposits exposed at the surface are Quaternary in age (~2.4 Mya to Present), with most of the geomorphic features first occurred during the Holocene.  The eolian deposits and some of the alluvial deposits first occurred as early as the Pleistocene.  

 

Notice the slope on the northeast and east side of the shaded relief map.  Quivira lies in a drainage basin, so the majority of the surficial groundwater runoff drains directly into the marshlands, combining with the recharge from Rattlesnake Creek.

 

SALINITY

 

Salty surface waters and salt flats at Big and Little Salt marshes at Quivira National Wildlife Refuge in Stafford County are caused by natural saltwater in the underlying bedrock. Underlying the surface deposits of windblown dune sand is the Great Bend Prairie aquifer, water-bearing deposits of sand and gravel. As the water evaporates, salt concentrations increase. The Quivira marshes and the surrounding area are a common discharge center, where freshwater and saltwater aquifers converge, and a veneer of wind-blown dune sand caps the surface. The average salinity of Little Salt Marsh is approximately 2,500 ppm chloride, whereas that of Big Salt Marsh ranges from 5,000 to 10,000 ppm (sea water averages 19,000 ppm chloride, and drinking water about 250 ppm).

The Rattlesnake Creek corridor is the major avenue for releasing significant salt quantities from the Permian zone to the land surface. Use of Rattlesnake Creek water for the survival of the wildlife refuge in the Quivira marsh area represents an innovative combination of natural phenomena with engineering ingenuity. However, dry-season streamflows are not reliably adequate for the needs of the wildlife refuge, and efforts are in progress to resolve the problems of competing demands for regionally limited water resources.

Water is a universal solvent, dissolving and chemically reacting with the rock formations it encounters. The longer water remains in the aquifer and the greater the distance it travels, the more mineralized it becomes. Salinity at Quivira is not related to the Hutchinson Salt Member; instead, salinity here is related to the Cedar Hills Sandstone, and sandstone layers in the Salt Plain Formation  which lie above the Hutchinson salt. These rocks contain salt minerals-halite and anhydrite.  The Cedar Hills Sandstone aquifer is recharged in southwest Kansas. Regional ground-water flow carries this water, which becomes increasingly saline, in an easterly direction until it discharges near the surface into the overlying freshwater aquifer west of the Quivira marshes. A north-south-trending ridge of Permian bedrock below the marshes restricts the easterly movement of ground water toward the Arkansas River and forces saltwater to discharge into the low-lying streams and marshes.  

The Quivira marshes are characterized by poor drainage, springs and seeps with high salt concentrations, and salt-tolerant vegetation. Evaporation of shallow lakes concentrates salts on the bare ground, creating the white salt flats characteristic of the salt marsh.

HYDROLOGY

The surficial geology is composed of mainly dune sand with a high porosity, allowing the groundwater to seep into the soils and into the mineral deposits below.  Sand and gravel beds of the Meade formation are the most important sources of water in Stafford County and yield large supplies.

A channel was constructed by local duck clubs in the late 1920s or early 1930s to permit Rattlesnake Creek to flow directly into the Little Salt Marsh, one of two large saline marshes on the refuge. Additional canals and ponds have been constructed since, providing the entire area with a more dependable surface-water supply. However, in the late summer of dry years, an adequate water supply is still a problem as upstream water demands reduce the flow from Rattlesnake Creek to the Quivira National Wildlife Refuge.  The USGS is currently involved in a study to determine new management practices upstream to ease the reduced recharge from Rattlesnake Creek.

BIBLIOGRAPHY

http://www.kgs.ukans.edu/General/Geology/Barton/index.html

http://academic.emporia.edu/aberjame/field/flint/geomorph.htm