PLATE LXXII. 



SWAN LAKE PLATE OF THE MESABI IRON RANGE, 1899. U. S. GRANT. 



The strike of the most elevated part of the country represented by this plate is 

 occupied by the granite of the Giant's range. So far as known it is of a general 

 light color, or reddish gray, but a dark, hornblendic rock, one of the phases of the 

 Archean, is said to occur in sec. 25, T. 57-23. The Animikie, so far as known, con- 

 sists of only the quartzyte and taconyte members. In a drill-hole made in the north- 

 eastern part of sec. 1, T. 56-23, the taconyte was found to be 231 feet in thickness, 

 containing seams and bands of lean ore. Under the taconyte was quartzyte, which 

 was penetrated four and a half feet. 



The iron ore of the Mesabi Chief mine was one of the first bodies of ore discov- 

 ered within the area of this plate, situated S. W. sec. 23, T. 57-22. N. H. w. 





