370 abstracts: geology 



oils being consistently lower from year to year in esters to which the 

 characteristic aroma is largely due. The geographical source of hops 

 seems to be indicated by the ester content of the oils. A review of the 

 chemical investigations of the aromatic constituents of hops by other 

 investigators completes the paper. F. R. 



GEOLOGY. — Geology and geography of a portion of Lincoln County, 

 Wyoming. A. R. Schultz. U. S. Geological Survey Bulletin 543. 

 Pp. 141, with maps, sections, and views. 1914. 



Geological formations that outcrop in this area range in age from the 

 Cambrian to the Quaternary. The beds are closely folded and in places 

 overturned. The beds that strike in a north-south direction are exposed 

 in parallel belts throughout the field. Three coal groups have been 

 recognized, ranging in age from Cretaceous to Eocene, and one phosphate 

 group of Carboniferous age. 



Tht main disturbances giving rise to the structural features occurred 

 near the close of the Cretaceous, although minor movements have taken 

 place since the deposition of the Eocene beds. Besides the numerous 

 parallel folds and synclines that trend in a north-south direction, the beds 

 have been broken by two parallel thrust faults that lie from 6 to 15 miles 

 apart in an east-west direction and have been traced for a distance of 

 approximately 100 miles in the western part of Wyoming. Along these 

 faults the Carboniferous and Cambrian beds on the west come in con- 

 tact with beds of Colorado and Montana age on the east. 



The economic deposits of greatest importance are the coals. They 

 occur in the Frontier, Adaville, and Evanston formations and belong to 

 beds that are of Colorado, Montana-Laramie, and Eocene age, respec- 

 tively. The Frontier coal, a high-grade bituminous coal that does not 

 slack on exposure to air, has a heat value of from 12,000 to 14,000 B.t.u. 

 The Adaville and Evanston coals are subbituminous and break down 

 readily on exposure to air. The heat value is considerably less than that 

 of the Frontier coal and ranges from 10,000 to 12,000 B.t.u. The phos- 

 phate deposits occur throughout the area near the top of the Carbon- 

 iferous beds. Gold placers have been worked along Snake River and its 

 tributaries, but on account of the fineness of the gold the placer workings 

 have not been very successful. It requires from 1,000 to 1,200 colors 

 to make a cent value. The richest pay streaks in the gold-bearing sand 

 and gravel lie near bedrock and run from 9 cents to $3.00 per cubic- 

 yard, while some of the material is comparatively barren. 



A. R. S. 



