REVIEWS 329 



In the west production of gypsum is not very great, but a number of 

 states, especially Oklahoma, Wyoming, Utah, Nevada, California, 

 and New Mex'co have large reserves. The Wyoming deposits are 

 found in the Embar (Permian), Chugwater (Permian or Triassic), and 

 Spearfish (Triassic) formations. The deposits are in the Red Beds. 



In California the most promising deposits are south of San Francisco 

 Bay, associated with Tertiary and Pleistocene formations. The most 

 valuable are of the gypsite variety. Many of them lie on the side of 

 knobs or ridges. The deposits are due to the ground water being 

 drawn to the surface and evaporating, leaving behind its load of gypsum 

 acquired from the underlying rocks. There are two other forms of 

 deposits in the California districts, intermittent lake deposits and inter- 

 bedded deposits. 



In New Mexico there are large deposits of gypsum which have been 



developed but little. They occur as bedded deposits in the Manzana 



group of the Pennsylvanian and in the Wingate Sandstone of the Jurassic. 



In the top of the latter there is a bed 100 feet thick. Gypsum also 



occurs as surface crusts due to evaporation at the surface, and as dunes, 



the material being derived from such crusts. The dunes are in the 



Tulurosa Desert and cover an area of 270 square miles. The gypsum 



from the dunes is used to a slight extent. -r- -r^ r> 



F. P. S. 



Geology of Webster County and a Portion of Mingo District, Randolph 



County, South of Valley Fork of Elk River. By David B, 



Beger. West Virginia Geological Survey, 1920. Pp. 682, 



pis. 35, figs. 24, maps 2. 



Webster County lies in the Cumberland Plateau, the westernmost 



division of the Appalachian province. The topography is characterized 



by deep valleys cut into an old peneplain, the relief varying from 500 to 



1,000 feet. The structure is a gently southeastward dipping monocline 



with some minor folds. The stratigraphic range includes beds of the 



Upper Mississippian and Pennsylvanian. The Allegheny, and the 



Kanawha and New River groups of the Pottsville, form the greater part 



of the surface outcrops, the Monongahela having been entirely stripped 



off and the Conemaugh mostly. Mississippian formations, represented 



by the Mauch Chunk shales, of continental origin, and the Green Brier 



limestone, outcrop only in some of the deeper valleys of the county and 



in the included portion of Randolph County. The latter is remarkable 



for its profusion of marine forms. Devonian beds are known only from 



deep-well records. • 



