REVIEWS B25 
Geology and Water Resources of the Southern Half of the Black Hills 
and Adjoining Regions in South Dakota and Wyoming. By 
N. H. Darton. From the Twenty-first Annual Report of 
U. S. Geological Survey, Part IV. c 
In his report on the geology of the southern half of the Black 
Hills, Mr. Darton has given us not only a revision and elaboration of 
the facts previously known about that interesting region, but has added 
many which are new and important. The formations which he recog- 
nizes in the area are included in the following section: 
Pleistocene - - + River gravels and alluvium. 
Tertiary - - - + Oligocene—White River beds (unconformity). 
( Laramie. 
Fox Hills. 
Pierre shales. 
Niobrara chalk. 
Carlysle. 
Inoceramus limestone. 
Graneros shale. 
Dakota sandstone. 
Fuson. 
Minnewaste limestone. 
Lakota sandstone (unconformity). 
Beulah shales. 
Upper Cretaceous” - 
Benton 
Lower Cretaceous - 
Jurassic - - - Unkpapa sandstone. 
Sundance (unconformity). 
Triassic (?) = - Spearfish Red Beds. 
pees Minnekahta limestone. 
ermian - - - 
Opeche. 
Minnelusa. 
Pahasapa limestone. 
Englewood limestone (unconformity). 
Upper Carboniferous - 
Lower Carboniferous - 
Deadwood sandstone and conglomerate. 
Crystalline schists and granites. 
Cambrian - - - 
Algonkian - - - 
ea Oe 
Many of these names are new, and the significance of a few of the 
older ones has been altered, owing to the better information which the 
author has gathered regarding fossils and uncomformities. 
Although the report deals not only with the geologic history of the 
Black Hills, but with structure, hydrography, and resources of the 
region as well, a résumé of the first topic only is here given. 
Too little is known of the pre-Cambrian condition of the Black 
Hills to permit a discussion of it at present. The rocks of that age 
are a complex system of granites and schists which will require careful 
