December 19, 1902.] 



SCIENCE. 



985 



and titano magnetite is somewhat unusual; 

 Professor Vogt, in fact, declares that it is 

 not known to occur (Z. f. Prakt. Oeol., 1900, 

 p. 292) in the diilerentiated ores. The black 

 mineral immediately adjoining the olivines 

 contained, upon qualitative test, a large 

 amount of titanium. 



This locality has been described by Mr. 

 Arnold Hague in Vol. II. of the ' Reports of 

 the Survey of the 40th Parallel,' pp. 12-16, 

 but the county rock as described by him is a 

 reddish granite, an analysis of which is given. 

 Evidently the points where Mr. Hague saw the 

 deposit were not the same as the locality here 

 described, for the dike, as noted, extends over 

 a considerable distance. The only granitic 

 rock observed at the place described was a 

 small, dike-like mass of fine-grained biotite- 

 granite on the north side of the canyon, nearly 

 opposite the smaller dike of iron ore. 



A review of the available facts relating to 

 this interesting locality, which merits further 

 investigation, is to be found in J. F. Kemp's 

 ' Brief Review of the Titaniferous Magne- 

 tites ' in School of Mines Quarterly, Vol. 

 XX., No. 4, 1899. 



The analysis of the titano-magnetite by J. 

 P. Carson (F. V. Hayden, U. S. Geol. Surv. 

 Terr., 1870, p. 14) gives the following result: 



SiO. 76 



TiO, 23.49 



ALO3 3.98 



Cr.O, 2.4.5 



FeA 45.03 



FeO 17.96 



MnO 1.38 



MgO 1.5G 



CaO 1.16 



P.Os Tr. 



S 1.44 



ZnO 47 



99.78 

 Fe 45.49 %' 



Noteworthy is the large percentage of sul- 

 phur, indicating the presence of sulphides, 

 none of which was, however, observed in the 

 specimens. Further, the notable percentage 

 of zinc, a metal very unusual in the titano- 

 magnetites. There is also an unusually large 

 amount of Cr.O.. present. 



Mr. Alfred H. Brooks presented a paper 

 entitled 'A Reconnaissance in the Mt. Mc- 

 Kinley Region, Alaska,' which was the pre- 

 liminary announcement of the results of an 

 exploration made during the past season. 



Alaska is divisible into the same four geo- 

 graphic provinces as those of western Canada 

 and the United States, which are the Pacific 

 Mountain System, the Central Plateau Re- 

 gion, the Rocky Mountain System, and the 

 Arctic Plain Region. The area investigated 

 lay in the first of these two provinces. 



The Pacific Mountain System is made up 

 of a number of distinct ranges, of which the 

 rugged Alaskan lies farthest inland and is the 

 highest, embracing Mt. McKinley, the highest 

 peak on the continent. It extends in a north- 

 easterly and easterly direction from the vicin- 

 ity of Lake Clarke to the Tanana River, sep- 

 arating the Cook Inlet drainage on the south 

 from the Kuskokwim and Yukon waters on 

 the north. The crest line of the range lies 

 near its western and northern side, where th& 

 mountains fall off abruptly to a gravel-covered 

 plateau which slopes down to the Kuskokwim 

 lowland. The southern slope of the range- 

 also rises rather abruptly from the Sushitna 

 Valley lowland. 



A journey of some eight hundred miles was 

 made on foot, while a pack train of twenty- 

 horses was employed to transport the provi- 

 sions and equipment of a party of seven men. 

 The expedition left Tyonok, Cook Inlet, on 

 June 1, and, taking a northerly course, reached 

 the mouth of the Keechatna a month later; 

 then turning westward, crossed the Alaskan 

 Range by an unmapped pass to Kuskokwim 

 waters. Thence the route northeastward, 

 along the western base of the great Alaskan' 

 Range, was traversed to the Cantwell River. 

 An exploration of the headwaters of the left 

 fork of the Cantwell was made and then the 

 party turned northward across the Tanana and 

 reached the Yukon at Rampart on Septem- 

 ber 15. 



The continuous instrumental survey of the- 

 whole route forms a connecting link between 

 a number of reconnaissance surveys which- 

 had been made in previous years by the Geo- 

 logical Survey. Much interesting and val- 



