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Salina Basin Stratigraphy and Structure

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Stratigraphy, continued

Rocks of Cretaceous Age

The following Cretaceous rocks, listed in descending sequence, have been differentiated in outcrops in central and western Kansas:

Cretaceous System
Gulfian Series
Montana group
Pierre shale
Colorado group
Niobrara chalk
Carlile shale
Greenhorn limestone
Graneros shale
Dakota formation
Comanchean Series
Kiowa shale
Cheyenne sandstone

The Cretaceous rocks overlie the truncated outcrops of the Permian rocks. Permian formations younger than the Harper sandstone, and all rocks of Triassic and Jurassic age are absent in the area under discussion. The younger Permian rocks of southwestern Kansas must have spread across this part of Kansas but were later eroded. Triassic rocks, separated from the Permian by unconformities, were also deposited in the area but now reach only to the western margin of Phillips County and the northwestern corner of Rooks County (Lee and Merriam, 1954.)

The land surface across which the Cretaceous sea advanced had a mature relief sloping at a low angle toward the west. The local relief of this surface within a single county was at least 50 feet. The regional relief referred to a Cretaceous datum increases more than 300 feet from west to east as shown by the Kellett cross section (1932). Cretaceous rocks are 567 feet thick in sec. 13, T. 11 S., R. 17 W., in Ellis County, but increase to more than 1000 feet on the western border of the map.

The Niobrara chalk and older Cretaceous rocks are exposed on the western border of the Salina basin. Eastward these rocks and the younger formations of the Cretaceous were removed by erosion; only the Dakota sandstone extends as far east as Washington County.

Detailed studies of the Cretaceous rocks in central Kansas have been made by several geologists of the State Geological Survey. Plummer and Romary (1942) examined outcrops of the Dakota formation from Ellsworth County northeast to Washington County by means of open cuts for the purpose of studying the clays. Frye and Brazil (1943) studied the Cretaceous section in outcrops and in test holes drilled in Ellis and Russell counties in connection with ground-water studies. Swineford and Williams (1945) examined cuttings from many test wells in Russell County in the study of saltwater disposal problems. These reports, all of which deal with the Cretaceous within or bordering the Salina basin, have been drawn upon for descriptions of the subsurface character and thickness of the Cretaceous formations.

Comanchean Series

The Cheyenne sandstone is the basal deposit of the Cretaceous throughout most of western Kansas. It is reported to overlie the Morrison shale of Jurassic age in Norton County by Norton (1939) and in Gove County by Kellett (1932), but east of these areas the Cheyenne rests on the Permian. The Cheyenne sandstone consists predominantly of buff to light-gray sandstone with small amounts of shale and siltstone. These clastic materials were derived in large part from exposed Permian rocks, reworked by wave action of the eastwardly advancing sea. Their characteristics in Russell County (Swineford and Williams, 1945, p. 130) and probably elsewhere vary with the character of the rocks exposed on the underlying surface and in bordering areas. The sediments are characterized by relatively coarse sand, absence of shell fragments, and absence of mica in the coarser facies. The Cheyenne has a thickness of 200 feet in Ellis County. In Russell County, it ranges in thickness from a featheredge, where it overlaps upon topographic highs, to 62 feet. It wedges out on the pre-Cretaceous surface east of Russell County.

The Kiowa shale consists of gray to black thinly laminated shale, interbedded with thin lenticular bodies of white siltstone and sandstone. Locally the sandstone lentils are as much as 20 feet thick. Shell fragments and carbonaceous material are common. The sandstone bodies are slightly glauconitic, generally micaceous, and less coarse in grain than the sand in the overlying Dakota. The thickness of the Kiowa in Russell County ranges from 50 to 100 feet. The thinner deposits overlie hills of the Permian surface. The Kiowa overlaps the Cheyenne and thins out toward the east. It is absent in outcrops north of Ottawa County.

Gulfian Series

Colorado Group

The Dakota formation is composed dominantly of varicolored clay. It includes some siltstone, but very little shale. Fine-grained and coarse-grained sandstones are numerous but discontinuous. The sandstones are mainly channel deposits, and only a few can be traced from place to place. Despite their prominence in outcrops, the sandstones constitute only a minor element in the Dakota sequence. Siderite in concretions and pellets is abundant. Hematite, limonite, and carbonaceous material of various kinds are common. Lateral variation of all lithologic types is pronounced. Plummer and Romary (1942) report that the sediments are nonmarine and were seemingly deposited near sea level under conditions somewhat analogous to present conditions in the lower Mississippi delta. Careful measurements by Plummer and Romary (1942, fig. 4) at intervals from Ellis County northeast to Washington County reveal thicknesses of 270 feet in southern Ottawa County, where the Dakota overlies the Kiowa shale, and 190 feet in Washington County, where the Dakota overlaps upon the Permian. The thickness of the Dakota in Russell County ranges from 213 to 300 feet.

The Graneros shale in Russell County consists of dark-gray to brownish-black non calcareous shale interbedded with thin beds of fine-grained glauconitic sandstone. It is distinguished from the overlying Greenhorn limestone by the absence in the Graneros shale of calcareous material and the foraminifers Globigerina common in the Greenhorn, and by the presence of sheets of sandstone and siltstone. It is distinguished from the underlying Dakota by the occurrence of glauconite and pyrite in the Graneros, and by the absence of kaolin and siderite (Swineford and Williams, 1945). The thickness of the Graneros shale in Russell County ranges from 14 to 40 feet.

The Greenhorn limestone in Russell County consists of alternating beds of limestone and chalky shale. The upper limestone beds are chalky and not readily separated lithologically from the overlying Carlile shale. The lower beds are crystalline. Shell fragments and Globigerina are common in the cuttings. Some bentonite occurs in the lower part of the formation. The Greenhorn limestone is 85 to 110 feet thick in Ellis and Russell counties.

The Carlile shale is divided into three dissimilar lithologic units. The lower third, the Fairport chalky shale member, about 100 feet thick, consists of thin beds of chalky limestone distinguished with difficulty from the similar upper beds of the Greenhorn limestone. Most of the upper two-thirds of the Carlile (the Blue Hill shale member, 175 to 215 feet thick) is made up of gray-black fissile shale. At the top lies a sandstone member, the Codell sandstone, a few inches to 20 feet thick. Bass (1926a) reports that the Carlile shale in Ellis County is approximately 300 feet thick.

The Niobrara chalk is a thick sequence of alternating chalk and marl. The lower member, the Fort Hays limestone, averages about 55 feet in thickness and includes chalky limestone somewhat harder than the overlying rocks. The upper member, the Smoky Hill limestone, ranges from 450 to 700 feet in thickness. It consists mainly of chalk and marl interstratified with thin beds of chalky shale and numerous partings of bentonite as much as 6 inches thick. The total thickness of the Niobrara is 500 to 750 feet in the subsurface of Logan and Wallace counties, where it is overlain by the Pierre shale. Only the lower part of the Niobrara is represented on the western border of the Salina basin, where its thickness is less than 300 feet.

The condition of available rotary samples of the Cretaceous on the western margin of the Salina basin does not permit accurate determination of the contacts of the various Cretaceous formations.

Rocks of Tertiary and Quaternary Age

Tertiary and Quaternary deposits of continental origin occur in many localities in central Kansas. Rocks of Pliocene and early Pleistocene age, consisting of alluvial deposits of sand, silt, and clay, are as much as 180 feet thick in parts of McPherson County and adjacent counties (Moore, Frye, and Jewett, 1944, p. 148).

Quaternary deposits of Pleistocene and Recent age are also present in central Kansas. Sand, gravel, silt, and clay as much as 150 feet thick occur in places in McPherson and Republic counties and fill pre-glacial or early Pleistocene valleys. Glacial till mantles the uplands in the northeastern part of the Salina basin. Loess deposits cover extensive upland areas throughout the region. Highlevel terraces of different ages border ancient and recent valleys.


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Kansas Geological Survey, Geology
Placed on web Jan. 5, 2017; originally published Dec. 1956.
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