20 THE OKYSTAL FALLS IROiST-BEARING DISTRICT. 



Letters, the same article being published the following year in the American 

 Journal. The iron-bearing series of this district was in this article referred 

 to the Upper Marquette (Upper Huronian). 



1893. 



Wright, 0. E. Report of State geologist from May 1, 1885, to June 1, 1888, in 

 Rept. of tlie State Board of Geol. Survey of Michigau, 1893, pp. 33-44. 



State geologist, Charles E. Wright, in a report for the seasons from 1885 



to 1888, inclusi^-e, merely mentions the general strike of the rocks of the 



district, and makes no attempt to determine their age nor to unravel the 



structure. 



Wadsworth, M. E. Sketch of the geology of the iron, gold, and copper dis- 

 tricts of Jlichigau. In Rept. of State Board of Geol. Survey for years 1891-92, 1893, 

 pp. 75-186. 



Dr. M. E. Wadsworth, who on Mr. Wright's death succeeded him as State 

 geologist of Michigan, mentions the occurrence of carbonaceous slates, of 

 granite and melaphyre, and of conglomerate near Crystal Falls, but does not 

 enter into a discussion of the relations of any of these rocks. Dr. Wads- 

 worth agrees with the correlation of Professor Van Hise, and places the 

 Crystal Falls ore dejDOsits in the Upper Marquette series (Wadsworth's 

 Holyoke formation) (pp. 117, 132), but the evidence for so doing is not 

 given in the report. He also is the first to recognize the volcanic nature of 

 the rocks in the vicinity of Crystal Falls (p. 134). 



1S9-5. 



RoMiNGER, C. Geol. rept. on the Upper Peninsula of Michigan. Geol. Survey 

 bf Michigan, Yol. V, Part. 1, 1895, pp. 1-164. 



In his report of work done on the Upper Peninsula of Michigau from 



1881 to 1884, published in 1895, he follows the same plan, referring the 



various rocks exposed by mining operations to his different groups.-' 



Clements, J. Morgan. The volcanics of the Michigamme district of Michigan. 

 Jour, of Geol., Vol. Ill, 1895, pp. 801-822.2 



In a preliminnry article on this district, by the writer, published in 

 1895, the volcanic character of the rocks which cover a large area of the 

 Crystal Falls district was emphasized, and in a sketch map in the same 



' Geol. Survey of Micliigan, Vol. IV, 1881, p. 8. 



^ After the publication of this article, the name Michigamme haviug been applied to a formation, 

 it was deemed advisable, in order to avoid confusion, to change the name of the district to the Crystal 

 Falls district. 



