20 abstracts! geology 



ficially prospected. The deposits resemble in general character several 

 deposits, low in silver, in neighboring mining districts. G. F. L. 



GEOLOGY. — Reconaissance of oil and gas fields in Wayne and 

 McCreary counties, Kentucky. M. J. Munn. U. S. Geological 

 Survey Bulletin No. 579. Pp. 105. 1914. (Prepared in co- 

 operation with the Kentucky Geological Survey.) 

 The strata which outcrop in Wayne County have a maximum thick- 

 ness ranging between 1200 and 1500 feet. The upper part of the series 

 consists of sandstone, shale, conglomerate, clay, and coal belonging 

 to the Pennsylvania series ("Coal Measures") of the Carboniferous 

 system. These beds are underlain by about 1000 feet of Umestone, 

 shale, and thin sandstone, belonging to the Mississippian series ("sub- 

 Carboniferous"). Pennsylvanian rocks are absent over the northern 

 part of the county and along the principal streams, having been re- 

 moved by erosion. The maximum thickness, probably 400 or 500 

 feet, of Pennsylvanian rocks is found in the high hills along the southern 

 border of the county. The limestones and the red and green shales of 

 the upper part of the Mississippian series are exposed along the valleys 

 and hillsides of the mountainous region, and the limestones of the 

 middle and lower part form the surface of the rolling plain in the north- 

 ern and western portions of the county. These older beds consist of 

 20 to 40 feet of Devonian shale at the top, underlain unconformably 

 by Silurian or Ordovician limestones down to water level. Over 1500 

 feet of rocks, mostly limestones, which are not exposed at the surface, 

 are known to have been pierced by a few deep wells. 



Most of the oil in this district is found in a cherty geode-bearing 

 limestone called by drillers the Beaver Creek "sand." In well records 

 the Bearer Creek "sand" is shown to vary considerably in distance 

 above the top of the Chattanooga ("Black") shale. In many wells 

 it is as much as 60 feet above the Chattanooga shale, but in most 

 places where productive it appears to be only a few feet above that 

 shale, from which it is separated by light-green and blue clay shales. 

 The writer suspects that in many places where the Beaver Creek 

 "sand" is reported by producers to be "high" above the Chattanooga 

 shale, the true Beaver Creek "sand" may be absent, as in the Beaver 

 Creek mill section, and that certain limestones may have been mistaken 

 for it. 



The geologic structure of this region is that of a broad, compara- 

 tively shallow trough in which occur many minor anticlines and syn- 



