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Kirwin Dam

Photo of Kirwin Dam and Reservoir
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The bedrock in the sediments of Kirwin Dam is the Fort Hays limestone of the Niobrara foundation.  The Fort Hays overlies the Carlile shale, which forms the bedrock under valley section of the Dam.  Both of these formations are of Cretaceous Age.  The overburden in the area consists of reworked chalk covered with a thin layer of silt and sand (loess).  Numerous areas of lithologic color change indicating that the chalk is near the surface substantiate the thinness of the silt-sand layer.  Several seismic spreads were shot in such areas to verify this interpretation.  An example of chalk is revealed by a group of light colored patches about 700 feet south of the channel on the right abutment.

Last updated: Apr 02, 2013