REVIEWS 7?i7 



work. To science the able discussions of causes and effects, of climatic 



relations to geology, geography, and agriculture, of water-supply, etc., 



are the most attractive features. The pages devoted to underground 



water resources are specially strong. The only regret is that the paper 



is not finished. 



George D. Hubbard. 



Charleston, III. 



The Bauxite Deposits of Arkansas. By Charles Willard Hayes, 

 U. S. Geological Survey, Twenty-first Annual Report, Part 

 III, pp. 435-472. Maps and plates. 



Commercial deposits of bauxite have been known in Arkansas 

 since 1890, when they were first discovered by the State Geological 

 Survey. The present report by Dr. Hayes represents, however, the 

 first detailed systematic study of these deposits, and its appearance 

 when developments are just beginning in the area, makes it a very 

 timely one. 



Preliminary to the description of the Arkansas deposits proper, 

 the report opens with a brief summary of the "distribution of bauxite 

 deposits in the United States." The Arkansas deposits are limited 

 to a small area twenty miles long and five or six miles wide, lying 

 south and southwest of Little Rock, in the adjacent parts of Pulaski 

 and Saline counties. The most important deposits of the state are 

 grouped into two districts, with less important isolated ones between. 

 The general geologic and physiographic relations of the region are 

 recounted in some detail, derived largely, as the author says, from the 

 state survey reports. Three distinct groups of rocks are made out, 

 namely, the Paleozoic sediments in the northwest, the Tertiary and 

 recent sediments on the southeast, and areas of intrusive igneous 

 rocks in the two bauxite districts. The Paleozoic rocks are similarly 

 folded and closely resemble those of the Alabama-Georgia-Tennessee 

 area of the southern Appalachians. The region was probably several 

 times reduced to a nearly featureless plain, and sometime after the 

 folding, probably, during Cretaceous, the igneous rocks were, accord- 

 ing to Williams, intruded. Beginning with the Cretaceous, the region 

 was several times invaded by the sea and Tertiary sediments still form 

 a considerable part of the area. 



In the detailed description of the deposits, the two districts are 



