522 abstracts: geology 



GEOLOGY. — Preliminary report on the chromite of Kenai Peninsula, 

 Alaska. A. C. Gill. U. S. Geol. Survey Bull. 712-D. Pp. 

 31 (99-129), pis. 3. 1919. 



The chromite deposits of Kenai Peninsula are situated at two locali- 

 ties near the southwest end of the peninsula. One of these, the Claim 

 Point property near the coast, is the only producer of chrome ore in 

 Alaska, and furnished about 1000 tons yearly in 191 7 and 191 8. The 

 chromite occurs in masses of dunite, which are surrounded by beds 

 of more or less metamorphosed clastic rocks, chiefly slates and gray- 

 wackes. The outstanding peculiarity of the Kenai Peninsula chromite 

 bodies is their continuity for considerable distances in the shape of 

 bands or layers, as contrasted with the "pockety" character exhibited 

 by such ores at most localities. Estimates of exportable ore are: 

 Port Chatham (at coast), above tide level, 32,300 tons; below tide 

 level, 12,600 tons; Red Mountain (interior) 195,600 tons. 



J. D. Sears. 



GEOLOGY.— P/ace-r mining in the Tolovana District, Alaska. R. M. 

 OvERBECK. U. S. Geol. vSurvey Bull. 712-F. Pp. 8 (177-184). 

 1920. 



Mining in the Tolovana district in 1918 was practically restricted 

 to the gold placer deposits in the vicinity of Livengood, north of Fair- 

 banks. Other minerals occurring in the district, not yet known in 

 sufficient quantity to be of economic importance, are chromite, scheelite, 

 stibnite, and possibly platinum. The value of the output of placer 

 gold in the Tolovana district in 1918 was about $875,000, compared 

 with $1,160,000 in 1917. This is about 15 per cent of the total placer 

 gold production of Alaska in 19 18, and gives the Tolovana district 

 second place. The deposits of Livengood Creek and its branches are 

 described, of which most are buried or bench placers. The paper is 

 supplementary to a report on "The Gold Placers of the Tolovana Dis- 

 trict" by J. B. Mertie, Jr. (U. S. Geol. Survey Bull. 662: 221-277, 

 1917). J. D. Sears. 



GEOLOGY. — The Upton-Thornton oil field, Wyoming. E. T. Han- 

 cock. U. S. Geol. Survey Bull. 716-B. Pp. 18 (17-34), pi. i, 

 fig. I. 1920. 



The report deals with an area on the southwest flank of the Black 



