i6 The American Gcolot^ist. J"^-^'- ''^**^- 
jT^ranite boss. At many ])oints, as at Iron lake. Dog river, Dore 
river, Wawa lake, it contains pel)])les from the very characteris- 
tic iron formation which fixes its age as Upper Unronian. 
Within this conglomerate belt is a roughly oval area of 
granitoid gneiss, nineteen miles bv twenty-eight. This has al- 
ways been mapped as Laurentian because of the striking- litho- 
logical resemblance to the Ottawa gneiss. However, it is in 
undoubted eruptive relations with the conglomerate along the 
shore of Superior,'^ for example a few miles west of the 
Dore. A mile and a half up the Magpie, a boss of granite is in 
eruptive contact with the conglomerate, and although it may 
not be of the same age as the larger boss three miles to the 
northwest, it probably is. In the opposite direction a succes- 
sion of granite-gneiss bosses intrusive in the schists are found, 
for six miles, after which the granitoid gneiss occitrs without 
interruption for over a hundred miles. 
North of the mouth of Dog river and along ("atfish creek 
search along the contact will probablv show it to be an eruptive 
one. Nowhere has the granite gneiss been found in actual con- 
tact with the iron formation, but no search was made for it. 
It might be found on the north shore of Kabenung lake. On 
Paint lake an intrusive granite-gneiss boss cuts the iron forma- 
tion, and this is very probably of the same age as the similar 
eruptive rocks, two miles to the north and three to the south. 
The contacts of the granite gneiss with the green schists 
are much more numerous and in all cases the schists are the 
older. Eruptive in all the foregoing are numerous dikes of 
diabase which seem to be of Keweenawan age. Other dikes, 
restricted to the green schists, are of course older. 
If the facts here given are correct, the geological succes- 
sion is different on the north shore of Superior from that de-- 
termined on the south. There the larger areas of granite 
etc. are placed in the basement complex, later than the green 
schists but earlier than the lowest iron-bearing formation. 
Here a large area of granite-gneiss, nineteen miles l)y twenty- 
eight, is in eruptive contact with a conglomerate carrying very 
characteristic pebbles of the Lower Huroniau formation. Is 
this area of the same age as those usually designated Lauren- 
tian in Canada ? I think so, and for these reasons : — 
*See also Coleman, Bur. of Mines, Ontario, riii, p. 1<)6. 
