SEISMIC METHODS 



921 



5000 6000 7000 



\.- SEISMIC DEPTH POINT 



Fig. 571. — Profile, Del Norte Dam Site, Dike Section. (Courtesy 

 of U. S. Department of Interior, Bureau of Reclamation.) 



-SHEEP MTN 

 eiOO-f- ANDESITE 



MAIN DAM 



EL. 6039 



" ° CONEJOS FORMATION 

 HARD FLOW BRECCIA OR AGGLOMERATE 1'^^ 

 POSSIBLY ASH BEDS IN LOWER SECTION 



Driver gravel, sands, silts, 



SOME CLAY lenses 



10000 11000 12000 



feet 



13000 14000 

 ^77 = SEISMIC DEPTH POINT 



Fig. 572. — Profile, Del Norte Dam Site, Main Dam. (Courtesy of U. S. Department 

 of Interior, Bureau of Reclamation.) 



Reconnaissance Geophysical Survey of Three Alternate Dam Sites, 

 on the Smoky Hill River, Kansas 



A reconnaissance survey with the seismic refraction method was made 

 by John Baird, of the U.S. Bureau of Reclamation, in November, 1941, 

 covering 3 proposed dam sites on the Smoky Hill River in western Kansas, 

 The geophysical work was strictly of reconnaissance nature, as no drilling 

 was done with which to correlate and verify the seismic determinations of 

 bedrock depth. The exploration made it possible, however, to compare the 

 3 sites at a minimum cost and in a very short time, which is advantageous 

 in the planning stages of river basin development. 



The dam sites investigated were located in Grove and Logan Counties, 

 Kansas, about 23 miles from the town of Oakley. One site lay at Elkader, 

 and was called the Elkader Site. The second site, below Elkader, was 

 known as the Elkader Alternate No. 2 Dam Site. The third site, 7V2 miles 

 downstream from Elkader, was designated as the Pyramids Dam Site. 



Geology. — The general area is part of the typical uplands of west- 

 ern Kansas, having a considerable thickness of Tertiary beds at the surface. 



