RESUME OF LITERATURE. 79 



interstratified with carbonaceous shaly layers in places, which were more 

 or less highly ferriferous; (2) that by a process of silicification these car- 

 bonate-bearing layers were transformed into the various kinds of ferruginous 

 rocks now met with ; (3) that the iron thus removed from the rock at the 

 time of silicificatiou passed into solution in the percolating waters, was 

 redeposited in various places, and thus formed the ore bodies and bauds of 

 pure oxide of iron; (4) that in other places, instead of leaching out, the 

 iron has united with the silicifyhig waters to form the silicates uow found, 

 such as actinolite; (5) that the silicifying process went on partly before the 

 folding, partly afterward, and to the latter period belong probably the 

 larger bodies of crystalline ore. 



Willis, Bailey. Report of a trip on the Upper Mississippi and to Vermilion 

 Lake: Tenth Census Report, Vol. XV, 1886, pp. 457^67. 



Willis, in 1886, describes the rocks and the structure of a small part 

 of the Vermilion district. The area surveyed lies along the south shore of 

 Vermilion Lake, in T. 62 N., R. 15 W., and comprises about 8 square miles. 

 One mouth was devoted to the study of this, and although for the greater 

 part of the time work was done on snowshoes, many details were carefully 

 noted. Traverses were made one- eighth of a mile apart, and observations 

 for magnetic variation and dip were taken. 



The prominent topographic features are described as approximately 

 east and west trending anticlinal ridges of hard jasper, separated by syn- 

 clinal valleys, in which lie the younger and softer rocks. The north main 

 ridge or group of ridges is known as the Vermilion range. Southwest of 

 this, and separated from it by a valley three-fourths of a mile wide, extends 

 the Two Rivers range. Southeast of the Vermilion range lies Chester 

 Peak (this is now known as Jasper Peak), the west end of the third ridge. 

 The iron-bearing series has a dip of between 85° and 90°. The succession 

 from the base upwards is as follows: (1) Light-green, thinly laminated, 

 chloritic schist. (2) White, gray, brown, and bright-red jasper, inter- 

 stratified with layers of hard blue specular ore, which also occurs in ore 

 bodies of considerable superficial extent, running across the bedding; 

 thickness 200 to 600 feet or more. (3) Chloritic schist, similar to 1; original 

 thickness probably about 150 feet. (4) Quartzite, dark gray, white, or 

 black, of saccharoidal texture, containing grains of magnetite which 

 make it a readily recognized magnetic formation; probable thickness 200 



