Prev Page--Chemical Character of the Water || Next Page--Well Records
Geologic Formations in Relation to Ground Water
Permian System--Leonardian Stage
Wellington Formation
Character, distribution, and thickness
The Wellington Formation underlies all of Sumner County except possibly small areas in the valley of Arkansas River. In the eastern two-thirds of the county the formation crops out or is covered by Pleistocene deposits; in the western third of the county it is overlain by the Ninnescah Shale.
The Wellington Formation as now defined by the State Geological Survey of Kansas includes all beds between the Nolans Limestone below and the Ninnescah Shale above.
The lower 150 to 200 feet of the Wellington Formation consists principally of gray to greenish-gray silty shale but includes several discontinuous limestone and dolomitic limestone beds. A persistent bed of dolomitic limestone, the Hollenberg, lies about 35 to 40 feet above the base of the formation. A dolomitic limestone that somewhat resembles the Herington Limestone member of the Nolans Limestone is exposed in an abandoned quarry in the NW sec. 36, T. 31 S., R. 2 E. This limestone is regarded by Swineford (1955) and Norton (1939) as a lenticular bed within the Wellington Formation. An unusual bed of massive non-fossiliferous limestone is exposed in the NE sec. 21, T. 33 S., R. 2 E. This bed is stratigraphically at about the level of the Canton Limestone member but differs greatly from the beds classified as Carlton in the NW sec. 32, T. 34 S., R. 1 E (Swineford, 1955). A bed of gypsum crops out in the SW SE sec. 27, T. 33 S., R. 2 E. The thickness and lateral extent of the gypsum were not determined. The middle part of the Wellington Formation is composed of salt. The thickness of salt in Sumner County is greatest in the northwest corner but probably does not exceed 150 feet anywhere in the county.
The salt beds are overlain by about 300 feet of shale constituting the upper part of the Wellington Formation. Red and purplish-red shale is much more common in the upper part of the formation than in the lower part. The Milan Dolostone member, which crops out in the bank of Chikaskia River south of Milan, forms the top of the Wellington Formation. The Milan consists of three beds of dolomitic limestone containing flakes of bright-green copper carbonate, interbedded with a few feet of grayish-green shale. In many places in Sumner County the Milan cannot be recognized; hence the contact between the Wellington Formation and the overlying Ninnescah Shale is indefinite.
Water supply
The Wellington Formation yields only small quantities of water to wells in Sumner County. Most of the material composing the formation is almost impermeable, and the water comes from small fracture zones or from thin limestone lenses. For this reason the Wellington is extremely unpredictable as an aquifer. Many wells yield water that is strongly mineralized by material derived from the salt and gypsum beds in the formation. Strongly mineralized water under artesian pressure in the Wellington Formation west of Belle Plaine has contaminated the water in the overlying alluvium and terrace deposits of Ninnescah River.
Ninnescah Shale
Character, distribution, and thickness
The Ninnescah Shale crops out in the western third of Sumner County but is mantled locally by Pleistocene deposits. The Ninnescah Shale, like the Wellington Formation, forms an almost featureless topography of low relief and good exposures are rare. The best exposure is along U.S. Highway 81 south of Caldwell. The Ninnescah consists chiefly of reddish-brown silty shale containing many beds of thin calcareous siltstone and blocky reddish-brown shale having scattered greenish-gray spots, and, in the upper part, thin beds of very fine grained sandstone. Locally there are many small veinlets of gypsum or gypsiferous siltstone. Only a part of the Ninnescah Shale, about 250 feet, is present in Sumner County.
Water supply
The Ninnescah Shale yields small quantities of water to many wells in western Sumner County. Much of the water, like much of that from the Wellington Formation, is strongly mineralized. In general, the Ninnescah Shale is not as good an aquifer as the Wellington Formation.
Quaternary System--Pleistocene Series
Nebraskan Terrace Deposits
Character, distribution, and thickness
A high upland area in the northwest corner of Sumner County is mantled with sand and gravel of Nebraskan age. These deposits cover an area of about 30 square miles and seem to fill a broad, shallow channel or bedrock sag, which aligns approximately with the present course of Slate Creek. Deposits of Nebraskan age were probably much more extensive at one time, but they have been eroded away by Slate Creek and by tributaries to Chikaskia River.
The lower part of the Nebraskan deposits consists chiefly of fine to medium sand but includes minor amounts of coarse sand and arkosic gravel. The upper part consists of silt and tan or red sandy clay. The greatest known thickness of these deposits in Sumner County is about 90 feet.
Water supply
Nebraskan deposits yield moderate quantities of water of very good quality. In 1956 only one irrigation well was obtaining water from these deposits in Sumner County. Municipal wells of Conway Springs also obtain water from them.
Kansan or Illinoisan Terrace Deposits
Character, distribution, and thickness
Kansan and Illinoisan terrace deposits in Sumner County can generally be differentiated only on the basis of relative topographic position. The Kansan deposits, which occupy a higher topographic position than the Illinoisan deposits, have been eroded along their edges, and small quantities of reworked Kansan deposits have accumulated upon the Illinoisan deposits or upon the bedrock that occupies a topographic position between the Kansan and Illinoisan deposits. Illinoisan deposits in Sumner County are probably a part of the Crete Formation. Large areas of the county contain thin or discontinuous Kansan or Illinoisan deposits overlain by colluvium derived from the Ninnescah Shale and Wellington Formation. Because of the difficulty in distinguishing between the Kansan and Illinoisan deposits, they are treated as a single unit in this report. Sand and gravel, chiefly arkosic, are exposed in numerous road cuts and gravel pits, and many test holes were drilled through these deposits, which become coarser toward the base. In many places these rocks are recognizable as terrace deposits only because they occupy areas that roughly parallel present streams; they may be 50 feet or more above present flood plains. Their maximum known thickness in Sumner County is about 90 feet.
Water supply
The Kansan or Illinoisan terrace deposits yield moderate quantities of water to wells in Sumner County. The water from these deposits is of good quality except where it is polluted by oil-field brine.
Wisconsinan Terrace Deposits
Character, distribution, and thickness
Terrace deposits of Wisconinan age occur in all major stream valleys in Sumner County. These deposits represent the valley-filling phase of Wisconsinan glaciation and range in thickness from a featheredge to as much as 75 feet. The materials composing the Wisconsinan terrace deposits differ greatly from place to place, according to the type of material available to the stream that deposited them. Along Arkansas, Ninnescah, and Chikaskia Rivers they are composed chiefly of arkosic sand and gravel but include small amounts of silt and clay. Along Slate Creek, Bluff Creek, Fall Creek, and the other small creeks in Sumner County they include a much larger percentage of silt and clay and contain only minor amounts of sand and gravel.
Water supply
In Sumner County the Wisconsinan terrace deposits along Arkansas River yield large quantities of water of good quality except in local areas polluted by oil-field brine or sewage. Wisconsinan terrace deposits along Ninnescah River yield moderate to large quantities of water. In most of the valley, the quality of water from these deposits is good except for locally troublesome quantities of iron. In an area about 2 miles west of Belle Plaine, however, the Wisconsinan deposits rest upon that part of the Wellington Formation from which most of the Hutchinson Salt member has been removed by solution, and in this area salt water under artesian pressure enters the Wisconsinan deposits from the Wellington Formation, markedly increasing the chloride concentration in water from the Wisconsinan terrace deposits.
Colluvium
Character, distribution, and thickness
Much of Sumner County is mantled by an accumulation of colluvium. These deposits, of Illinoisan to Recent age, were formed partly by weathering of Permian shales in place and partly by deposition of silt, clay, and sand by sheet wash or unconcentrated wash. They rarely exceed 20 feet in thickness but in areas of low topographic relief they may completely conceal the underlying material over several square miles. On Plate 1 the colluvial deposits that overlie Permian shale are differentiated from those that overlie discontinuous Kansan or Illinoisan terrace deposits.
Water supply
Colluvium lies above the water table in most places, but yields small quantities of water to a few wells in Sumner County.
Recent Deposits--Alluvium
Character, distribution, and thickness
The Recent alluvium in Sumner County resembles lithologically the Wisconsinan terrace deposits from which most of it was derived. In the Arkansas, Ninnescah, and Chikaskia River valleys the basal part of the alluvial deposits consists of coarse sand and gravel, which grades upward into finer sand and silt. The alluvium of Bluff Creek is composed chiefly of fine sand, silt, and clay. In Slate Creek valley no contact between alluvium and Wisconsinan terrace deposits is discernible; therefore Recent alluvium in this valley is presumed to be present only in the bottom of the creek channel. Because alluvium and Wisconsinan terrace deposits cannot be differentiated in the subsurface, the entire thickness of unconsolidated sediments underlying the flood plains of the streams is treated as Recent alluvium in logs and sections.
Water supply
The alluvium of Arkansas River yields very large quantities of water, which varies in quality considerably from place to place. In general, the ground water in the alluvium near the river is of poorer quality than that farther from the river, because of infiltration of surface water laden with sewage and other wastes. In the Oxford area, water in the alluvium is badly polluted by oil-field brines.
The alluvium of Ninnescah and Chikaskia Rivers and Cowskin Creek yields moderate to large quantities of water. The water is good except in an area along Ninnescah River near Belle Flame, where there has been some natural pollution by artesian brine. The alluvium of Bluff Creek yields small to moderate quantities of hard water.
Recent Deposits--Dune Sand
Character, distribution, and thickness
Numerous dune tracts border Chikaskia and Arkansas Rivers. Most of these tracts lie on the north side of the rivers or north of certain large loops or bends in the rivers. The dunes are composed mainly of fine- to medium-grained well-rounded quartz sand, which has been blown from the flood plains of the rivers by the prevailing south winds. Many of the dunes are only sparsely vegetated and are subject to blowouts during periods of strong wind and drought.
Water supply
The sand dunes are above the water table and do not yield water to wells, but because of their high porosity and permeability and incomplete drainage, they serve as important recharge areas.
Prev Page--Chemical Character of the Water || Next Page--Well Records
Kansas Geological Survey, Geology
Placed on web January 2003; originally published August 1961.
Comments to webadmin@kgs.ku.edu
The URL for this page is http://www.kgs.ku.edu/General/Geology/Sumner/06_form.html