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General Geology
Summary of Stratigraphy
[Note: The stratigraphic classification used in this report is that of the State Geological Survey of Kansas.]
The rocks cropping out in Rice County are of sedimentary origin. The oldest rocks exposed at the surface are classed as the Sumner group, Leonardian Series, Permian. Red and green Ninnescah shale is exposed in the bluff bordering the lower part of Little Arkansas River Valley. Capping these bluffs is the resistant Stone Corral dolomite and a thin remnant of the Chikaskia member of the Harper sandstone. Siltstone and fine-grained sandstone of the Cheyenne sandstone unconformably overlie the Permian in northwestern Rice County. Dark shales and fine-grained sandstones of the Kiowa shale overlie the Cheyenne and Permian and are exposed in the Little Arkansas River drainage system, and at isolated points along the northern border of the Arkansas River Valley. Sandstone and highly colored clays of the Dakota formation crop out above the Kiowa in the headwater drainage of Little Arkansas River and at scattered points throughout the northern part of the county. Isolated erosional remnants of Tertiary rocks occur in at least three points in the western part of the county. Pleistocene to Recent loess, silt, sand, and gravel cover most of the area.
A generalized section of the geologic formations of this area is given in Table 1. More detailed descriptions of these units are given in the section on geologic formations and their water-bearing characteristics.
Table 1--Generalized section of the geologic formation of Rice County, Kansas
| System | Series | Subdivisions | Thickness (feet) |
Character | Water Supply |
|---|---|---|---|---|---|
| Quaternary | Recent | Alluvium | 0-30 (?) | Silt, sand, and gravel in a mile-wide strip along Arkansas River. | Yields brackish water to a few domestic and stock wells. |
| Dune sand | 0-40 | Sand. medium; some fine sand and silt. | Generally above the water table. Yields water to a few wells in the large dune tracts. | ||
| Pleistocene | Late Wisconsinan terraces | 0-60 | Gravel and sand: contains some silt in Arkansas River Valley and consists mostly of silt in tributary valleys to the north. | Yields large supplies of moderately hard water in Arkansas River Valley. | |
| Sanborn formation | 0-120 | Silt, massive; contains some sand and locally thick gravel and sand. (Contains Loveland, Peoria, and Bignell silt members, and Todd Valley sand member). | Does not yield water to wells in most of the area, but yields large supplies of water of good quality to wells in the area of Chase Channel and small supplies to domestic and stock wells locally. | ||
| Meade formation | 0-40± | Sand and gravel at base. locally cemented by calcium carbonate; massive silt and caliche in upper part. Locally contains volcanic ash. (Contains Grand Island and Sappa members.) | Yields small supplies of moderately hard water to domestic and stock wells in northern Rice County. | ||
| Chase Channel formation | 0-70 | Sand and gravel at base; silt and caliche in upper part. (Contains Holdrege and Fullerton members.) | Yields meager supplies of moderately hard water to very few domestic and stock wells. Thick channel gravels contain highly mineralized water. | ||
| Tertiary | Pliocene | Ogallala | 0-20 | Sand, gravel, silt, and limestone. | Yields little or no water to wells in this area. |
| Cretaceous | Gulfian | Dakota formation | 0-150 | Brown, yellowish-brown. and light-gray, medium-grained sandstone and varicolored clay. | Yields moderate to large supplies of good water to domestic, stock, municipal, and industrial wells in northern Rice County. |
| Comanchean | Kiowa shale | 0-130 | Brown, yellowish-brown and light-gray, medium- to fine-grained sandstone in upper part. Dark-gray to black fissile shale in lower part. | Upper part yields moderate supplies of good water to domestic, stock, and municipal wells. Lower part yields little water to wells. | |
| Cheyenne sandstone | 0-40 | White, light-gray, and greenish-gray siltstone and fine sandstone. | Generally yields no water to wells in Rice County | ||
| Permian | Leonardian | Harper sandstone | 0-200± | Red siltstone and very fine silty sandstone. | Yields small quantities of mineralized water to domestic and stock wells in area of outcrop. |
| Stone Corral dolomite | 0-30 | White and light-gray anhydrite and dolomite. | Yields little or no water to wells in Rice County. | ||
| Ninnescah shale | 200-300± | Red and light greenish-gray shale, siltstone, and very fine, silty sandstone. | Yields small quantities of mineralized water to domestic and stock wells in area of outcrop. |
Geologic History
Paleozoic Era
Records of deep drilling in Rice County have shown that a thick section of Paleozoic rocks is present above the pre-Cambrian surface. The pre-Cambrian surface has been encountered at depths of 3,240 to 4,100 feet. Marine Cambrian and Ordovician rocks were deposited over this igneous and metamorphic floor. Silurian and Devonian rocks are absent over most of the county. They either were not deposited over much of the area or were removed by erosion following the pre-Mississippian uplift of the Ellis arch. The southeastern tip of the Ellis arch extends into Rice County and pre-Mississippian rocks in part of northwestern Rice County were removed by erosion, leaving the pre-Cambrian surface exposed. Cambrian and Ordovician rocks in the southeastern part of the county on the flanks of the uplift were tilted and beveled by erosion. They are angularly unconformable with the overlying Mississippian rocks, which were later deposited in at least part of the area (Moore and Jewett, 1942).
The Mississippian rocks were later tilted and uplifted by the crustal movements that formed the central Kansas uplift which extends into Rice County from the north-northwest. Mississippian rocks were removed by erosion over most of the county. Tilted Mississippian rocks are encountered in the southeastern and extreme eastern part of the county on the flanks of the uplift. The area was again submerged (Moore and Jewett, 1942, p. 483), and more than 3,500 feet of Pennsylvanian and Permian beds were deposited on the beveled erosional surface of the earlier rocks. Lower Pennsylvanian beds are in contact with pre-Cambrian igneous and metamorphic rocks in parts of northwestern Rice County. Cambro-Ordovician beds overlie most of the area with Mississippian rocks in the southeastern and extreme eastern parts of the county.
Another major period of emergence and erosion followed the deposition of the Permian. Thick red shales, salt, gypsum, and anhydrite occur in the upper part of the Permian. A major unconformity at the contact of the Permian with the overlying Cretaceous rocks indicates a long period of erosion.
Mesozoic Era
The area was probably land during Triassic and Jurassic time. Deposition was renewed in early Cretaceous time when fine-grained sandstones and siltstones of the Cheyenne sandstone were deposited on the eroded surface of the Permian.
The dark marine shales of the Kiowa were deposited above the Cheyenne. At many points in the county, the Kiowa rests directly on Permian rocks. There is evidence of a minor erosional interval between the Cheyenne and Kiowa rocks.
As the comparatively shallow Kiowa seas receded, the area was covered by near-shore marine sandstone and beach deposits. Alternating marine and continental deposits near the close of Early Cretaceous time indicate near-shore conditions and an oscillating shore line. Plummer and Romary (1942, p. 342) have compared the conditions of deposition of the sandstones and clays of the Dakota, which immediately overlies the Kiowa, to conditions of sedimentation existing in the lower Mississippi River delta. In such an environment, shifting stream channels deposited sand, silt, and clay over a wide area slightly above sea level. Deposition barely balanced submergence of the land mass. Such conditions of sedimentation can be postulated for most of the Dakota formation.
That marine Cretaceous beds were deposited over the Dakota formation in the county is indicated by the presence of Graneros and Greenhorn beds a short distance to the north and west. It is estimated that at least 900 feet of Cretaceous beds were removed by erosion following the uplift at the close of the Cretaceous.
Cenozoic Era
Rice County probably was subjected to erosion during most of the Tertiary Period and by late Tertiary it was an area of low relief. Remnants of late Tertiary sediments are found in the western, northwestern, and central parts of the county. Twenty feet of partially cemented sand, silt, and gravel, capped by "Algal" limestone, is the greatest thickness of Tertiary material recorded in the county.
Renewed erosion in early Pleistocene deeply dissected this surface. Deep valleys were carved into Cretaceous and underlying Permian beds. The extent of the topographic relief in early Pleistocene time was as great as 230 feet within 5 miles, as indicated by the difference between the altitude of the top of the Tertiary and the base of the earliest Pleistocene deposits. At least four major changes in the relative effectiveness of the forces of erosion and deposition during the Pleistocene are recorded in the thick unconsolidated deposits mantling the rugged early Pleistocene topography.
History of Drainage
The development of drainage patterns in Rice County during Pleistocene time was controlled by the low base level afforded by the deep channels to the southeast. It was modified by the northward migrations of through-flowing streams from the Rocky Mountains.
At the close of the Tertiary, Rice County was an area of low relief. Before the close of the Nebraskan (glacial) Age, a low base level had been developed in the McPherson channel area to the southeast. Two streams traversing Rice County eroded to depths of about 230 feet below the top of the Tertiary. One channel cuts through only the extreme southwestern corner of the county. The other channel runs through the Chase Channel (Pl. 2, G2a), which enters Rice County at the west in T. 19 S., R. 10 W., just north of Silica and extends southeast, underlying Chase, passes just northeast of Sterling, and leaves the county in T. 21 S., R. 7 W. (Fig. 5). Both channels follow a southeasterly course. These deep channels were partly filled during Nebraskan and Aftonian time with gravel, sand, and silt. The upper part of the silt shows some evidence of prolonged soil development.
Figure 5--Map of Rice County showing the general topography of the Cretaceous and older rocks. Except where Cretaceous and older rocks are exposed at the surface, these contours show the base of the Pleistocene or, where present, the base of the Tertiary deposits.
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Renewed erosion in Kansan time followed approximately the same pattern. More lateral erosion and deposition and less downcutting was produced by Kansan streams in comparison to those of Nebraskan age. A through-flowing stream carrying gravel of the Rocky Mountain type, flowed through the southwestern part of the county. Erosion was again renewed in the Chase Channel, which was still in tributary relationship to the main drainage. Locally derived gravel was deposited in the Chase Channel and granitic gravel was deposited in the southern trunk stream. Smaller tributaries north of the Chase Channel reduced the Cretaceous bedrock to its present level over most of this area (Fig. 5).
The period from late Kansan to the beginning of Wisconsinan was mainly one of silt deposition. Loess, silt, and sandy silt were deposited over most of the area. Volcanic ash was deposited in local low areas above the sand or sandy silt. Records of erosion and channel filling in Illinoian time, if present in Rice County, are not identifiable from present data. Silt of Illinoian age rests on the silt of late Kansan age over most of the county without a recognizable intervening channel stage. Climatic changes during the Illinoian Age may have left no appreciable record in Rice County.
In early Wisconsinan time renewed erosion resulted in the capture of the ancestral Arkansas River through the Chase Channel. At the time of deposition of gravel and sand of early Wisconsinan age, Arkansas River in Rice County reached a point several miles north of its present northernmost position in Kansas. The early Wisconsinan gravel in the Chase Channel marks the northern extremity reached by a major through-flowing stream in Rice County.
In later Wisconsinan time Arkansas River abandoned the Chase Channel and migrated southward, leaving a broad alluvial plain from Lyons to the present position of Arkansas River. Remnants of three small terrace scarps below the early Wisconsinan terrace are present in this area, representing three stages of down cutting and deposition from middle Wisconsinan to Recent time.
The present northern tributaries in Rice County follow roughly the drainage patterns established in Kansan time. Cow Creek flows along the northeastern border of Arkansas River terrace deposits. In its upstream part, it flows at the extreme northern boundary of the old abandoned Chase Channel. Its pattern is an illustration of the northward migration of streams in this area. Throughout its entire course, it is bordered on the south by thick deposits of sand and gravel, and on the north by thick silt deposits filling valleys in the maturely dissected Cretaceous beds. Tributary streams are numerous north and northeast of this creek, but southern and southwestern tributaries are few and poorly developed. The explanation for this condition may lie in the difference between the permeability of the upland silt and the coarse gravel of the terrace deposits. There is very little surface runoff from the sand and gravel of the river terraces. Rain falling on the surface percolates downward and becomes part of the ground-water body. Therefore, development of streams and their consequent dissection is retarded. On the north side of the stream, the unconsolidated silt of the upland offers ideal conditions for erosion. The low permeability of the silt diverts most of the rainfall to surface runoff. The silt and loess is easily removed by downcutting, slope movement, and lateral migration of the resultant gullies and streams.
Northward shifting sand dunes on the old river terraces also act to interrupt and pond tributaries on the south. Examples of this are seen in the dune-interrupted drainage and ponding 3 miles south of Lyons, along Cow Creek south of Bushton, and south of Rattlesnake Creek southwest of Alden, especially in sec. 14, T. 21 S., R. 10 W. (Pl. 11).
A drainage map of the county (Pl. 1) shows the intricate dissection by numerous streams north of Cow Creek and a slight development of tributaries south of the creek. The abrupt northward bend in the creek in sec. 12, T. 19 S., R. 10 W. is evidence of a minor piracy of the stream by one of its own tributaries and demonstrates the general northward migration.
The present Arkansas River has a braided channel. Its channel becomes choked with sand and gravel in times of flood, and in lowerwater stages the river flows through, rather than over, its pervious ohannet. In contrast, the northern tributary streams are actively down cutting the deep, easily eroded Pleistocene fills over which they flow. The northward migration of the ancestral Arkansas River in this area is linked with the deep valleys eroded in early Nebraskan time and the later filling of these valleys with material susceptible to erosion. In recurrent humid cycles the overloaded stream from the Rocky Mountain region was subjected to a series of captures by rapidly downcutting streams to the north.
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Kansas Geological Survey, Geohydrology
Placed on web June 16, 2015; originally published July 1950.
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