No. 2.] SPENCER — COPPER-BEARING ROCKS. 65 



bility of the existence of some sponges in Michipicoten Island. 

 I know of no other evidences of life during this period, unless 

 the carbonaceous matter in the Lower Group of the Series on 

 the North Shore points in this direction. Consequently it is 

 stratigraphy and lithology that must disclose the venerable age 

 of these interesting deposits. 



Pumpelly has recently shown that the Cupriferous and Huron- 

 ian Series appear to be conformable, both in dip and strike, for a 

 distance of 30 miles from the Montreal River, on the borders of 

 Wisconsin, to Lake Gogebic — dipping northward at angles of 

 from 50 to 70 degrees. This is the only known exposure of 

 their junction on the South Shore. On the North Shore, Bell 

 has ascertained that the Nipigon Series is unconformable to the 

 Huronian in some places, while in others it rests on the upturn- 

 ed edges of the Laurentian. Again the great horizontal trap 

 overflows, which c ip so m my hills north of Lake Superior, are 

 lancomformable to the other beds of the series. These capping 

 trap beds are not present on the South Shore. 



The western side of the range, forming the backbone of Ke- 

 weenaw Peninsula, is overlaid by sandstones similar to those of 

 the Cupriferous Series and apparently conformable to it. East- 

 ward of this range the shores of Like Superior are skirted by a 

 narrow belt of red sandstones and shale>, dipping according to 

 Pumpelly at angles varying from 5 to 15 degrees towards the lake 

 basin. Over these red sandstones, the country east of the mineral 

 ranges is covered with light colored sandstones, ofteu friable, 

 which are deposited horizontally, and are supposed to belong to 

 the Potsdam Period. They contain no fossils themselves, but 

 are overlaid b} T ether rocks, containing a few organic remains, 

 which have been referred to the Calciferousor Chazy Formation; 

 and these are overlaid by the fossififerous Trenton deposits. 

 The sandstones, on the east side of Keweenaw Point, overlie the 

 Huronian deposits, and in many places contain pebbles of that 

 series. It is not known if the Cupriferous rocks any where in- 

 tervene between the sandstoues and the materials belonging to 

 the Huronian Age ; but the western border of the sandstones 

 abut against the upturned edges of the copper- bearing range, 

 which dip away from them at angles varying from 40 y to 60 Q . 

 By some it has been urged that the line or junction, between the 

 igneous and sedimentary formations, represents the plane of a 

 gigantic tUult, in which case there has been a down-throw whose 



