Coolidge sinkhole From the KGS- Coolidge Sink--On December 18, 1926, a hole suddenly appeared in the ground 15 miles south of Coolidge, Hamilton County (NE sec. 22, T. 25 S., R. 43 W.). On July 1, 1930, the sinkhole was reported to be about 60 feet in diameter and 40 feet deep (Bass, 1931). It was circular with a steep and undercut wall; the floor sloped at a low angle toward the center of the depression. Three sets of crevices encircled the structure. By August 8, 1930, the sinkhole had enlarged to a diameter of 104 feet and increased in depth to 68 feet (Bass, 1931). The material in which the sinkhole was formed was homogeneous silt; no stratified rock could be seen in the hole. Smith reported that in 1940 water filled the hole to within 10 feet of the surface and that the wall had slumped so that no overhang was visible. The depression had increased in size to 150 by 200 feet in 1941 and had elongated from its original circular shape, engulfing a nearby country road. It also had filled with water to within 15 feet of the rim (McLaughlin, 1943). Bass attributed the sinkhole to solution and formation of a cavern with subsequent collapse of the roof. He reported that bedrock dips at 5 toward the sinkhole, indicating that the entire area of recent subsidence may be part of a larger and older sinkhole. Landes (1931) studied the area and determined that Graneros Shale was exposed below the rim. From this, Landes decided that the original cavern must have been formed in either salt or gypsum in the Permian section. Smith found that this sinkhole is but one of a linear series and suggested that they occur along a post-Ogallala fault.
Posted on: Fri, 10 Oct 2014 02:53:07 +0000
Trending Topics
Recently Viewed Topics
© 2015