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  Finney and Gray county Geohydrology

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Table of Contents

Abstract

Introduction

Geography

Geology

Geologic History

Ground Water

Utilization

Quality of Water

Geologic Formations

Records of Typical Wells

Logs of Test Holes

References

Plates

 

Ground Water, continued

Artesian Conditions

Artesian water is ground water under sufficient pressure to rise above the point at which it is encountered in wells. A well that flows at the land surface is known as a flowing artesian well.

Artesian conditions exist where a water-bearing bed is overlain by an impermeable or relatively impermeable bed that dips from its outcrop to the discharge area (Sayre, 1937, p. 22). Water enters the water-bearing bed at the outcrop and percolates slowly downward to be held in the water-bearing bed by the overlying confining bed. Down the dip from the outcrop area, the water exerts considerable pressure against the confining bed. When a well is drilled through the confining bed into the water-bearing bed the pressure is released and the water rises in the well. If the water is under sufficient pressure, and if the altitude of the land surface is lower than the altitude of the outcrop of the water-bearing bed, the water may rise high enough to flow at the surface. In places where there are lenses or beds of relatively impermeable clay or silt at the level of the water table, the water encountered below such lenses or beds will rise to the level of the surrounding water table, but such water is under normal pressure and is not artesian.

There is only one flowing well (119) in this area to my knowledge. It is on the R.J. Ackley land in the SW 1/4 SW 1/4 sec. 4, T. 23 S., R. 33 W., and is reported to be between 70 and 80 feet deep. Figure 10 illustrates the probable geologic conditions that cause this well to flow. Well A in the illustration is situated on the uplands under normal water-table conditions. Well B, however, is situated in a depression, the surface of which is below the water table. Water encountered in the sands and gravels below the lens of impermeable silt or clay will rise above the land surface to the level of the surrounding water table. Such water is under normal pressure and is not artesian. Well 119 furnishes water to a pond which covers a part of the depression. The level of the water in the pond probably is below the level of the surrounding water table, for the amount of water lost by transpiration and evaporation is greater than the amount of water supplied by the well. If no water were lost through transpiration and evaporation, the water level in the pond should be at the same level as the surrounding water table.

Figure 10--Diagrammatic geologic section across an upland depression showing relationship between a flowing well and and non-flowing well.

flowing well has outlet above water table

Artesian water has been encountered by wells in areas adjacent to the Finney-Gray area. The largest area of flowing wells in the state is in the Meade basin in central Meade County, which adjoins Gray County on the south. There were more than 200 flowing wells in the Meade district in 1939 (Frye, 1942, p. 52). Most of the artesian water in the Meade basin is obtained from Pliocene deposits, but some comes from Pleistocene beds. According to Frye (1942, p. 49):

"... alternate beds of permeable and relatively impermeable material dip downward beneath the floor of the Meade artesian basin. Water entering the permeable strata northwest of this area at an elevation higher than the floor of the basin moves down the dip between the confining layers of relatively impervious material toward the lowest part of the basin, where it is under artesian pressure."
Small flowing wells in southwestern Ford County obtain artesian water from the Rexroad member of the Ogallala formation (Pliocene) and from overlying Pleistocene beds (Waite, 1942, p. 50). Waite (1942, p. 50) also reports a small flowing well in the Arkansas valley, about. 3 miles east of the Gray-Ford County line, which obtains artesian water from the Ogallala formation. The Dakota formation (Cretaceous) supplies artesian water to wells in some areas. Moss (1932, pp. 45, 46) reports that there are several flowing wells from the Dakota formation in Sawlog creek valley in southern Hodgeman County.

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  Kansas Geological Survey, Finney and Gray County Geohydrology
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Web version April 2002. Original publication date Dec. 1944.
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