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Kansas Geological Survey, Open-File Rept. 96-1a
Proposed Management Areas--Page 3 of 16

Other Significant Aquifer/Aquitard Units Influencing the Dakota Aquifer

Over its extent in Kansas, the Dakota Formation is overlain by younger Upper Cretaceous bedrock units and Cenozoic unconsolidated deposits (Table 1, Figure 1). The Upper Cretaceous sequence consists of shale, chalk, and limestone belonging to the Graneros Shale, the Greenhorn Limestone, the Carlile Shale, the Niobrara Chalk, and the Pierre Shale. The total thickness of this sequence generally increases to the west and north in Kansas up to more than 2,400 ft in the northwest corner of the state. These stratigraphic units form the Upper Cretaceous aquitard (Figure 1). In most of southwest and most of south-central Kansas and much of southeastern Colorado, the Upper Cretaceous aquitard has been eroded and the Dakota is overlain by and hydraulically connected to the overlying High Plains aquifer (Figure 1). In the river valleys of the central part of the state the Dakota aquifer is in hydraulic connection with the overlying saturated alluvial deposits which form the alluvial valley aquifers (Figure 1).

Westward dipping Jurassic and Permian rocks directly underlie the Dakota aquifer in Kansas. In southwestern Kansas the Jurassic Morrison Formation consists mostly of sandstone and is a source of fresh water along with the Cheyenne Sandstone. In central Kansas, the Cedar Hills Sandstone is a saltwater-bearing aquifer that is hydraulically connected to the lower Dakota aquifer (Table 1, Figure 1).

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Kansas Geological Survey, Dakota Aquifer Program
Original report available from the Kansas Geological Survey.
Electronic version placed online July 1996
Scientific comments to P. Allen Macfarlane
Web comments to webadmin@kgs.ku.edu