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Table of Contents

Abstract

Introduction

Geography

Geology

Ground Water

Formations

Well Records

Logs of Test Holes

References

Plates

Geology

Summary of Stratigraphy

The character and groundwater supply of the geologic formations in Ford County are described briefly in the following generalized section (table 1) and in more detail under "Water-bearing formations."

Table 1--Generalized section of the geologic formations of Ford County, Kansas.

System	Series	Subdivision		Thickness (feet)	Character	Water Supply
Quaternary	Pleistocene and Recent	Alluvium and Terrace deposits		0-60	Sand, gravel, and silt, comprising stream deposits in the Arkansas valley and in the valleys of many smaller streams. Coarse gravels occur as terrace deposits bordering the present flood plain of Arkansas River at levels 15 to 25 feet above the flood plai	The alluvium yields large supplies of water to wells in the Arkansas valley and lesser amounts in the smaller stream valleys; supplies many irrigation wells in the Arkansas valley. Some waters from the alluvium are very hard, containing from 238 to 1,413
		unconformable on older formations
		Dune sand		0-70	Fine eolian sand. Except where reopened by recent blowouts, the dunes are well stabilized by vegetation.	Probably does not supply water directly to wells, but constitutes favorable catchment area for ground-water recharge to adjacent and underlying formations.
		unconformable on older formations
		Kingsdown silt		0-135	Predominantly light buff, even-bedded soft silt and clay containing small, scattered lime nodules; contains unstratified loess in its upper part which grades gradually upward into loess of Pleistocene and Recent age. Contains light-colored sand and gravel	Yields little or no water in its upper part, but sand and gravel deposits near the base may furnish some water to wells where the water table lies above them. Most of the Kingsdown silt is dry and relatively impermeable.
disconformity
Tertiary	Middle and upper Pliocene	Ogallala formation	Rexroad member	20-250	Alternating beds of gray to greenish clay, buff-colored sandy silt, and rusty sand and gravel. Gravel contains many large-sized pebbles and water-worn fragments of caliche. Has not been recognized north of Arkansas River. (May contain some beds in upper p	Yields good supplies of water to most of the wells located on the uplands south of Arkansas River, including most of the irrigation wells.
			disconformity
					Gravel, sands, silts, caliche and structureless silt and silty sand with hard and soft layers of sandstone and conglomerate, south of which is cross-bedded and cemented with lime. Gravel and coarse sand are abundant in the basal part, and lime-cemented be	The principal source of water supply in many parts of the county. Yields adequate supplies of water of good quality to domestic, stock, municipal, and industrial wells. Supplies water to many irrigation wells, particularly to deep wells in the Arkansas va
unconformable on older formations
Cretaceous		Greenhorn limestone	Pfeifer shale member	20 +/-	Chalky shale with beds of thin chalky limestone, discoidal concretions, and thin beds of bentonite. "Fencepost" limestone at top.	Very few wells obtain water supplies from the Greenhorn limestone in the county. Only very limited supplies of comparatively hard water may be expected from wells penetrating this formation. In general, the water is hard, ranging in hardness from about 35
			Jetmore chalk member	20 +/-	Alternating beds of chalky shale and chalky limestone, "Shell" limestone at top.
			Hartland shale member	80	Chalky shale with a few thin beds of chalky limestone and bentonite.
			Lincoln limestone member		Yellowish chalky shale with hard, thin-bedded, finely-laminated, crystalline limestone at top and bottom, and a few thin beds of chalky limestone.
		Graneros shale		43-45	Dark bluish-black, fissile, noncalcareous clay shale with numerous thin lenses of sandy shale, sandstone, and interbedded ironstone concretions. Outcrops are strewn with selenite crystals.	Practically barren of water; no wells are known to derive water supplies from this formation in the county. Any water that might be encountered probably would be highly mineralized and very bitter to the taste.
		Dakota formation		56-235	Fine-grained, gray to white to yellow-grained, quartz sandstone with interbedded bluish-gray, silty and sandy shale.	Yields moderate supplies of water of good quality to wells in the northeastern part of the county. Several irrigation wells in the extreme southwestern corner of the county tap the Dakota, but obtain most of their water from the overlying Ogallala formati
		Kiowa shale		44 +	Black to bluish-black to gray to yellowish-gray argillaceous shales with a few thin beds of yellowish or pinkish limestone. Not exposed in county.	Not known to yield water to wells in Ford County.
		Cheyenne sandstone		70 +	Light gray to yellow, fine to coarse-grained, quartz sandstone with interbedded bluish-gray, silty ad sandy shale	Not known to yield water to wells in Ford County.
unconformity

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