454 abstracts: geology 



The structure of the Uinta upUft, considered as a whole, is com- 

 paratively simple. On closer study, however, the long, narrow, flat- 

 topped east-west fold which is here called the Uinta anticline is found 

 to be much more complex and to consist of numerous secondary anti- 

 clines and synclines, some parallel to the main axis and others at right 

 angles to it. There are also numerous low cross folds along the flanks 

 of the major fold, expressed in undulations, local sags, and irregularities 

 along both sides of the range. The anticlinal fold is further compli- 

 cated by many normal faults and some thrust faults, both parallel and 

 transverse to the strike of the beds. The major structural feature of 

 the Uinta Mountains, however, consists of a huge east- west anticlinal 

 arch approximately 100 miles long, and from 35 to 50 miles in width. 

 This huge arch, which consists of rocks ranging in age from pre-Cam- 

 brian to Tertiary, separates the Green River Basin on the north from 

 the Uinta Basin on the south. 



The distribution of the phosphate beds and the Park City formation, 

 which contains them and which is equivalent to the Phosphoria forma- 

 tion and the upper part of the Wells formation of eastern Idaho in the 

 Bear Lake region, is shown by a map. 



The analyses show considerable variation, but they indicate the pres- 

 ence of some high-grade rock that carries approximately the equivalent 

 of 70 per cent of tricalcium phosphate. 



No detailed work upon which to base a reliable estimate of tonnage 

 has been done in this field. It is apparent, however, from the recon- 

 naissance examination that a large amount of phosphate is present. 



R. W. Stone. 



GEOLOGY. — The gold placers of the Tolovana district, Alaska. J. B. 



Mertie, Jr. U. S. Geol. Survey Bull. 662-D. Pp. 221-277, 



with maps and illustrations. 1917. 

 The Tolovana district lies in the northwestern part of the Fairbanks 

 quadrangle, in the headwater region of Tolovana River and Hess 

 Creek. The report describes the gold placers of Livengood Creek and 

 near-by streams and the geology and mineral resources of the surrounding 

 territory, designated the Tolovana district. Much emphasis is placed 

 on topographic anomalies in the form of extensive changes in drainage, 

 and on Quaternary deposits and their history, all of which is intimately 

 related to the distribution of the gold. The origin of the gold in its 

 bedrock sources in the vicinity of Livengood Creek is related to the 

 intrusion of siliceous igneous rocks, with the subsequent escape of min- 

 eralizing solutions therefrom. 



