CANADA 



345 



In tlie Eeport of Progress from 1863 to 18GG (pp. 127-129), Mr. 

 Thomas Macfarlanc describes the contact of some supposed Ilurouian 

 with Laurentiau rocks as follows : — 



" Tlie manner in which these Huronian rocks adjoin tliose of the Laurentian 

 series may be observed on the north shore between Michipicoten Harbour and 

 Idand. I paid aonic attention to tliat point of junction which lies to the west 

 of Eagle River, the precipitous dill's to the east of which, consist principally of 

 diabase schist and greenstone slate. A few miles to the west of these cliffs, 

 and at a point bearing N. 29° 5° E., from the east end of Michipicoten Ishmd, 

 the Laurentian granite is penetrated by enormous dykes of dense basaltic 

 greenstone (having the ]:)eculiar doleritic glitter when fractured) which contain 

 fragments of granite. This greenstone is also seen in large masses, which can 

 scarcely be called dykes, overlying the granite, and enclosing huge masses of 

 that rock, one of which I observed to be cut by a small vein of the greenstone. 

 From this point to Eagle River, those two rocks alternately occupy the space 

 along the shore, seldom in such a manner as to shew any regular superposition 

 of the greenstone on the granite, but almost always more or less in contact 

 ■with each other. The greenstone, however, becomes more frequent towards 

 the east, and at Eagle River it has almost replaced the granite, and assumed a 

 lighter colour, and an irregular schistose structure. The strike of these schists 

 is at places quite inconstant ; they wind in all directions, and what appear 

 at first sight to be quartz veins, accompany their contortions. On closer in- 

 spection, however, of the largest of these, they are seen to be of granite, but 

 -whether twisted fragments of that rock, or really veins of it, is at first glance 

 very uncertain. Observed su])erficially they have the appearance of veins, 

 but they do not preserve a straight course, and bend with the windings of the 

 enclosing schist. They often thin out to a small point and disappear, and, a 

 few feet or inches further on in the direction of the strike, reappear and con- 

 tinue for a short distance. Sometimes a vein thins out at both ends, and forms 

 a piece of granitic material of a lenticular shape, always lying parallel with the 

 stratific^ition. Although they are seldom or never angular, they can scarcely 

 be regarded otherwise than as fragments whose shape has been modified by 



contact with the greenstone There would seem to be only two ways of 



explaining the phenomena above described. Either the granite forms veins, 

 penetrating the schistose greenstones, in which case the latter are the older 

 rocks ; or it is in the form of contorted fragments, in M^hich case the inclosing 

 rocks may be of eruptive origin. The latter supposition seems to be most in 

 harmony with the facts stated, and with what is known as to the relative ages 

 of the Laurentian and Huronian rocks. I may here remark that in Foster and 

 Whitney's Lake Superior Report (Part II., pp. 44 and 45) analogous phenomena 

 are described, but the exactly opposite conclusion is arrived at, viz.: that the 

 granite is in veins, and forms the newer rock. Similar relations are observed at 

 other points of junction on the north shore, and the peculiar breccia, described 

 among the greenstones above mentioned, occurs at no great distance from one 



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