REVIEWS 331 



author finds that while agriculture is the leading source of wealth, 

 mineral industries are gradually gaining in importance. In 1916, 

 Illinois ranked behind Pennsylvania and West Virginia only, in the total 

 value of mineral production. It ranks first in the country in the pro- 

 duction of fluorspar, sand and gravel, and tripoli, third in brick and tile, 

 and coal, and fourth in petroleum, limestone, and clay products. An 

 extensive bibliography is included. 



Part III, ''Clay Deposits Near Mountain Glen, Union County, 

 Illinois," by Stuart St. Clair, describes the occurrence of a deposit of 

 clay believed to be superior to the foreign product for the manufacture 

 of graphite crucibles and glass pots. It is a bedded deposit, underlain 

 by sand, and overlain by sand, gravel, and in some places by an iron- 

 cemented conglomerate, the whole being covered by loess to varying 

 depths. The base never has been determined by drilling. The sedi- 

 mentary origin is evident. The area where it is was part of a great 

 Cretaceous-Tertiary embayment. The existence of this deposit has 

 been known for many years, but its development was delayed until the 

 cutting-off of the importation of German refractory clays by the war. 

 Four clay pits are now being worked. 



Part IV, "The Structure of the La Salle Anticline," by Gilbert H. 

 Cady. The La Salle Anticline is an asymmetric fold, extending south 

 from La Salle to the oil fields of Crawford and Lawrence counties. It is 

 bordered on either side by synclinal troughs, that on the east forming the 

 northern part of the Indiana coal basin, and that on the west forming the 

 larger and main portion of the Illinois coal fields. There are numerous 

 minor structures. The stratigraphic section includes beds from the St. 

 Peter sandstone through the Pennsylvanian. Several unconformities 

 are described. These are at the base of the Chester and the Pennsylvan- 

 ian, between the St. Peter sandstone and Platteville dolomite, between 

 the Lower Magnesian limestone and the St. Peter sandstone, and several 

 within the Pennsylvanian. The author suggests that there may be 

 some possible relation between the anticline and the distribution of the 

 areas of dolomization in the Platteville formation. 



Two structural contour maps of the area are given. The key beds 

 used in mapping were the top of the St. Peter sandstone and No. 2 

 coal of the Pennsylvanian. a p MrF 



The White River Badlands. By Cleophus C. O'Harra. South 

 Dakota School of Mines, Bull. No. 13. Rapid City, 1920. 



This is a useful volume on the badlands of South Dakota. It out- 

 lines the development of knowledge concerning the region, its geology, 



