66 THE CANADIAN NATURALIST. [Vol. viiL 



veriicn] depth would equal three miles or more. Near Houirhton, 

 there are some isolated pitches of sandstone, which overlie beds of 

 melaphyre,and contain numerous pebbles both of melaphyre and of 

 Cupriferous Conglomerate, consequently showing their subsequent 



origin. As pointed cut by the Geologic 1 Survey, the Copper- 

 Bearing Rocks were greatly sculptured before the deposition of 

 the s nd-tones; as there are pi ces where the old hills were de- 

 nuded leaving cliffs £00 feet high, having formed the old shore 

 line, along which the Potsdam (?) deposits were b ing m ide. 



The lithologic 1 characters of the Cupriferous Rocks resemble 

 those of the Permian and Tria-sic Periods. As shown by De~ 

 lesse, Naumann, Macf.rlane, Bell and others, no rocks of similar 

 lithological stiucture occur in any other part of the known world 

 belonging to an older period than the Carboniferous or the Per- 

 mian A»es. Now, if the Huronian Formation hid been thrown 

 into its present position, or nearly so, before the deposition of the 

 Cupriferous Series, and the horizontal sandstones east of the 

 range did not bi ar evidences of a subsequent origin, (although 

 only in a few small isolated pitches are they known to overlie 

 directly the Copper- Bearing Formation), then there would be 

 no stratigniphical grounds whatever for the determination of 

 the a<_ie of the rocks under consideration, and we could only 

 look to their lithological structure as a means of solving this 

 interesting question. Again, M cfarlane points out the trachytic 

 character of some of the rocks of this series which are situated 

 on Michipicoten Inlands, and this resemblance to modern vol- 

 canic products, which are not known to exist elsewhere in the 

 Nipigon Series, might point to a comparatively recent d its. 



But. the most recent investigations on the South Shore, m.ide 

 by Pumpelly and Brooks, go to shew that the Huronian Series, 

 in part, had not been uplifted to any extent before the deposi- 

 tion of the Nipigon or Copper- Bearing Rocks, as the two forma- 

 tions are conform ble, and tilted together at higli angles, while afc 

 no great distance from their junction, the Huronian is also con- 

 torted aid oveil .id by the horizontal Potsdam (?) sandstones. 

 As we have seen the range v»as sculptured before the deposition 

 of the sandstones, and the m >re recent origin of the latter rocks 

 appears to be addition illy confirmed by the isolated pitches near 

 Houghton containing Cupriferous pebbles. 



If the ancient Mineral Range on Keweenaw Peninsula were 

 not an old shore l.ne (of which there are numerous iudicutions), 



