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Morton County Geology

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Morton County is in the southwestern corner of Kansas and is a part of the southern High Plains section of the Great Plains province. It is relatively flat and is drained by Cimarron River and its tributaries. The county has a semiarid climate, the average annual precipitation being about 18 inches. Wheat farming is the principal occupation, but row crops are cultivated extensively in the areas of dune sand south of Cimarron River.

The depth to the ground-water table ranges from about 30 feet in the northwestern part of the county to about 225 feet in the southeastern part. The water table slopes eastward at an average rate of about 19 feet to the mile. The maximum slope, which is in the northwestern part of the county, is about 40 feet to the mile. The minimum slope is 7 feet to the mile, in the northeastern corner of the county.

The ground-water reservoir is recharged by flood waters in the ephemeral streams north of Cimarron River, by direct precipitation on the areas of dune sand south of the river, and by precipitation in the county or on the outcrops of water-bearing beds in near-by areas.

Water is discharged from the ground-water reservoir by wells, by seepage into Cimarron River, and by transpiration and evaporation in the Cimarron River valley. There is also a gradual subsurface movement of ground water eastward out of the county.

Most of the wells in this area are drilled, but a few are bored or dug. The water is principally for domestic and stock use but some is used for public, railroad, or irrigation supplies.

The ground water in this area is hard, but it is suitable for most ordinary uses. The waters from the Cockrum sandstone, the Ogallala formation, and the Cheyenne sandstone are similar in composition and hardness. Waters from the alluvium and from the Triassic (?) and Permian redbeds are very hard and are not suitable for domestic use. Much of the water contains fluoride in amounts that may be harmful, particularly the water from the Cockrum sandstone.

There are six divisions of the stratified rocks in Morton County that contain water supplies useful to man. These water-bearing rocks range in age from Permian to Recent. The Permian redbeds yield mineralized water to flowing artesian wells at depths of 550 to 700 feet near Richfield. The water contains considerable calcium and sulfate derived from gypsum associated with the redbeds.

The Triassic (?) redbeds yield water from beds at two horizons. The upper zone of buff sandstone yields moderately hard water to wells in the vicinity of Point Rock on Cimarron River. Flowing artesian wells are obtainable in the lower zone of red sandstone and siltstone near Point Rock, and the water is reported to be highly mineralized. The Triassic (?) redbeds are in places over-lain by the clays and marls of the Morrison (?) formation, which probably yield little or no water to wells in this county.

The next younger formation, the Cheyenne sandstone, yields water to wells in the northwestern part of the county at depths of 172 to 215 feet. The Kiowa shale has a low permeability and probably yields little or no water to wells.

The Cockrum sandstone overlies the Kiowa shale and yields water to most of the wells in the northwestern quarter of the county at depths of 30 to 125 feet.

Most of the county is underlain by undifferentiated silt, sand, and gravel of Pliocene and Pleistocene age. The Ogallala formation (Pliocene), consisting of silt, sand, and gravel, is the principal water bearer in the county and yields water to wells in all but the northwestern part of the county. The depth to water level in the Ogallala ranges from 60 feet in the northern part of the county to 225 feet in the southeastern part of the county. The Ogallala formation lies unconformably on rocks of Permian to Cretaceous age. The Ogallala formation and the overlying undifferentiated Pleistocene deposits are overlain, north of the river, by a thin blanket of loess. South of the river they are covered by dune sand.

In the Cimarron River valley are deposits of alluvium that yield very hard water to shallow stock wells.

Logs of test holes, water wells, and gas wells are given in the report. The data on water wells, on chemical analyses of waters, and on water-table fluctuations are listed in tables. The surface geology of the county, the depths to the water table, and the shape of the water table are shown on maps.

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Kansas Geological Survey, Morton County Geohydrology
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Web version Sept. 2004. Original publication date March 1942.