INTRODUCTION. ,31 



Cole, gave invaluable aid. In 1899 the company began a cai-eful geologic 

 survey of its lands, which was made in far greater detail than was 

 possible by the United States Greological Survey under existing conditions. 

 This private survey was carried out by Mr. W. N. Merriam, assisted in 

 1900 by Mr. Oscar Rohn. All of the material resulting from this survey 

 has been placed at the disposal of the wi-iter and his collaborators; a great 

 deal has been used in compiling the maps published herewith, and it has 

 added very materially to their completeness. Moreover, Mr. Merriam has 

 taken pains to make drawings, some of which are reproduced in this report 

 (credited to him), and otherwise to render assistance. To the company 

 which he represents, and to him es^^ecially, the United States geologists are 

 deeply indebted. The writer wishes also to acknowledge here the great 

 assistance rendered by Mr. E. R. Maurer and Mr. C. F. Graff, who have 

 prepared the drawings from which the maps and plates are made, and by 

 Mr. F. B. Van Horn, his efficient stenographer. 



SCOPE OF THE PAPER. 



The attempt has been made to make this report a complete epitome of 

 our knowledge of the Vermilion district. At the same time many details 

 have necessarily been omitLed, althoug'h in most cases these concern the 

 formations of the district that are not of economic value and are not likely 

 to become important. These details, without adding to the general results, 

 would have very much increased the bulk of the volume. Moreover, it 

 was feared that they would obscure important facts and thus defeat the 

 object of the monograph. 



The report is intended primarily to give to mining men and to present 

 and prospective owners of property in the district information concerning 

 the distribution of the important iron-bearing forinations and their relations 

 to the other rocks associated with them. The text gives a full description 

 of these formations. 



The atlas of maps and the plates in the volume are for the purpose of 

 aiding in an understanding of the textual descriptions. Actually observed 

 exposures of the rocks of the district could not be indicated in all cases on 

 the maps because their scale is too small. Large-scaled maps of certain 

 portions of the district that contain the important iron-bearing formation 

 in its best development, and in which areas any industrial developments 



