18 LETTER OF TRANSMITTAL. 



part of the work has been a general supervision of the survey. This 

 has involved frequent trips into the district, made in order to assist in 

 solving the general structural problems. 



In our work on the Vermilion district we have had the willing help of 

 the officers in charge of the mines, and we are very greatly indebted to 

 them for their assistance. In this connection we would especially mention 

 Mr. D. H. Bacon, who formerly was president of the Minnesota Iron Com- 

 pany, and Mr. T. F. Cole, now president and general manager of the 

 Minnesota Iron Company. 



Very respectfully, C. R. Van Hise, 



Geologist in Charge. 

 Hon. Charles D. Walcott, 



Director of United States Geological Survey. 



