12 THE CRYSTAL PALLS IRON-BEARING DISTRICT. 



of the Marquette district have now been ascertained/ it is hoped, by means- 

 of the determination of the succession in the intermediate Crystal Falls 

 district, that the Menominee rocks may be closely correlated with those of 

 the Marquette district. 



The accurate delimitation of the iron-bearing or coal-bearing forma- 

 tions, or any other formations containing valuable mineral products, is of 

 inestimable value to miners and investors. In the iron districts of Michigan 

 alone innumerable test pits have been sunk in areas of solid granite, and at 

 great distances outside of the possible iron formations, thus wasting large 

 sums of money. Although the investigations carried on in the Crystal Falls 

 district, the results of which are here recorded, do not enable us to point out 

 definitely the places where the prospector will find iron deposits, they have 

 enabled us to delimit in a broad way the various formations, and wan-ant 

 the statement that iron deposits may occur in certain areas and that the 

 prospector will assuredly not find iron deposits in certain others. 



The opportunity of studying the Crystal Falls district was given me 

 tlu'ough Prof C. R. Van Hise. In the prosecution of the field studies and 

 in the preparation of the report I have availed myself of his advice and 

 suggestions, which have been generously offered and which have been 

 found of greatest value. To him I am most deeply indebted. 



The report is based not only on my own field work, but also on the 

 field work done by a number of other geologists, whose notebooks have 

 been placed at my disposal. The names of these geologists may be found on 

 page 22. Among them, the notes of Mr. W. N. Merriam and Dr. W. S. 

 Bayley have been found especially valuable. Mr. Merriam, assisted by Dr. 

 Bayley, spent a season in doing very detailed work on the area shown on the 

 sketch map at the bottom of PI. Ill, between Crystal Falls and Mansfield, 

 and from this point northwest to some distance beyond Amasa. The mag- 

 netic lines represented in this part were traced by Mr. Merriam, and the 

 geology in general is the same that he outlined on his final field map 



I wish to thank Mr. C. K. Leith, who has been of the greatest clerical 

 assistance, and Mr. E. C. Bebb, by whom the maps were drawn; also Mr. 



' The Marquette iron-beariDg district of Michigan (preliminary), by C. R. Van Hise and W. S. 

 Bayley; with a chapter on the Republic Trough, by H. L. Smyth: Fifteenth Ann. Rept. U. S. Geol. 

 Survey, 1895, pp. 477-650. Ibid, (tinal), Mon. U. S. Geol. Survey, Vol. XXVIII, 1897. 



