204 C. K. VAN HISE — PRE-CAMBRIAN OF THE BLACK HILLS. 



area by the Rocky Mountain division of the United States < reological Survey 

 under the direction of Major Powell. This work was entrusted to Messrs. 

 Henry N< wton and Walter P. Jenney— Newtou as geologist and Jenney as 

 mining expert. Newton's death occurred before Ids report was ready for 

 the printer, and it was edited by Mr. G. K.Gilbert. The large monograph* 

 which appeared as the result of Newton and Jenney's field-work contains, 

 besides their reports, chapters by Whitfield. Caswell, Gray, and Tuttle upon 

 their respectn From the time of its appearance this work has 



ii the great authority on Black Hills geology, and of it- excellenci 

 which are due alike to the ability of Newton and the skill and insight "I' the 

 editor, all later geological visit »rs to the Black Hills have spoken. 



Work in this region subsequ ml to that of Newton and Jenney has been 

 in the nature of various brief visits by different geologists for particular 

 objects. Devereux f speaks of the geology of the Black Hills in connection 

 with the origin of certain gold ores. EmmonsJ gives a brief geological 

 Bketch of the region in the Tenth Census reports. Blake, § in Mineral 

 Resources of the United States, makes a u-w remarks on its geology. The 

 most important articles from a geological point of view, however, which have 



appeared due,' Newton and Jenney'.- m igraph are by Crosby and Car. 



I„iiter.* Their field-work was done together, and their articles have many 

 point- in common. 



Scope of Paper. 



The present paper is based upon a visit to the Black Hills during the 



.-mi -r of 1889. Like those who have preceded me, since the time of 



Newton and Jenney, my object was specific rather than geueralin its nature. 

 In the field-work I had tic assi tance of Professor C. W. Hall. I am also 

 indebted to IV >f - >rs I'. R. Carpenter and William I*. Headden, and Mr. 

 Tii' Kuntz ai, all of the Dakota Sch 10I of Mines, for important informa- 



tion as to localities and roads, while Professor Headden kindly made an 

 i 1 1 -, » the relations of the Cambrian sandstone and the granite 



in the vicinity of Hayward. No attempt was ma le to study the formations 

 of the Hill- or t» revise the .• inclusions that had been before reached, with 

 the exception of the pre < lambriaa rocks. Tl ailed A.rchean core, using 



the term of Newton, was traversed from north to south and east to west. 



i is. By Henrj 



' reu \ : 

 of the United 



W. l'. : ' I, pp 



HUt.. Vol \ \ II ' 



i 



i| of Min ' 



Mill lllu, Hoffra in. i---. pp, 171. 



