114 THE VERMILION IRON-BEARING DISTRICT. 



is the result of a more intense metamorphism, carried even to fusion of 

 some strata. These conchxsions result particularly from the study of a 

 section from Tower northward through Vermilion Lake, and of an area on 

 the west side of Outlet Bay, in the corners of sees. 13, 14, 21, and 32, T. 

 63 N., R. 1 7 W., and along the shore for one-half mile westward. 



It is evident that the Stuntz conglomerate on the south shore of Ver- 

 milion Lake is a true water-deposited conglomerate of the same formation 

 as the slates and graywackes of the district, the conglomerate grading 

 into the quartzite and graywacke, and this into argillaceous slate. Further- 

 more, as supposed by Van Hise, the conglomerate lies unconformably on 

 the iron-bearing formation, and contains very numerous fragments of 

 jaspilite. The position of this unconformity, whether at the base of the 

 Taconic or lower, is not ascertained. 



1S98. 



Grant, U. S. Sketch of the geology of the eastern end of the Mesabi iron 

 range in Minnesota: Engineers' Year Book, Univ. of Minn., 1S9S, pp. 49-62; 

 with sketch map. 



Grant sketches the geology of the eastern end of the Mesabi iron range 

 in Minnesota, including T. 64 N., Rs. 3 and 4 W., and parts of Rs. 2 and 

 5 W., with some adjacent portions of Ontario. The rocks can be separated 

 into three divisions. The chief one of these is the Animikie series, contain- 

 ing the iron-bearing rocks of the Mesabi range. Older than the Animikie 

 is a series of granites, greenstone both massive and schistose, conglomerates, 

 slates, and other clastic rocks, called the ]3re-Animikie. Younger than the 

 Animikie are some diabase sills and the Grreat gabbro mass of northeastern 

 Minnesota. 



Of the pre- Animikie rocks, the greenstones and clastic rocks have been 

 called Keewatin.- As the greenstones are usually associated with the 

 Mesabi iron-bearing rocks, these alone of the Keewatin rocks are described. 

 They lie to the north of the iron-bearing rocks in T. 65 N , R. 5 W., and 

 extend eastward to the center of T. 65 N., R. 4 W., where they disappear 

 under the Animikie strata. In general, the greenstones are at present 

 diorites; originally some were certainly diabases, others were of the nature 

 of andesites, and a large part were diorites or possibly gabbros. At places, 

 especially along the east side of sec. 27, T. 65 N., R. 5 W., the greenstones 



