THE LOWER HURONIAN. 305 



jaspers, then these slates are accounted for, as they occur in conglomerates 

 younger than and containing- fragments of the jasper. In a similar way 

 the cong'lomerate or breccia pebbles observed can be accounted for. It 

 should be noted, however, in connection with the explanation of the source 

 of these pebbles, that we do not know Avhether they are true conglomerates 

 or merely friction breccias, or pseudo-conglomerates. In the greenstone 

 south of Moose Lake there were numerous small zones which had been so 

 extremely fractured and then after the fracturing had been so sheared that 

 in many cases friction breccias have been produced which closely resemble 

 normal conglomerates and from which it would be perfectly possible to 

 derive the pebbles seen in the overlying conglomerates were the breccias 

 produced before the sediments were formed. 



Relations to the cjramte of Saganaga Lake. — In the northeastern part of 

 the district the Ogishke conglomerate is very close to the granite of 

 Saganaga Lake and in several places contacts between these two rocks 

 have been found and their relationships thereby made perfectly clear. In 

 several places a great bowlder conglomerate has been found immediately 

 overlying the granite of Saganaga Lake and consisting- essentially of frag- 

 ments of this granite. Detailed description has already been given of the 

 field relations of the granite of Saganaga Lake to this conglomerate under 

 the description of the granite (p. 271), and it was there shown that the idea 

 held by Lawson that the granite of Saganaga Lake was intrusive in the 

 conglomerate was untenable," hence it will not be necessary to repeat this 

 description here. From the evidence it is perfectly clear that the Ogishke 

 conglomerate is younger than the granite of Sag-anaga Lake. 



RELATIONS TO LOWER HUKONIAN. 



Relations to the Giants Range, Snowbank, and Cacaquabic granites, and 

 various dikes of granite and granite-porphyry. — In the western portion of 

 the Vermilion district there is found a conglomerate — correlated with the 

 Ogishke conglomerate — which is in contact with the Giants Range granite, 

 and has been penetrated by dikes from this granite. In the vicinity of 

 Snowbank Lake a similar conglomerate practicalh' suiTounds the area 

 underlain by the Snowbank granite, and in a great number of cases it has 

 been found to have been penetrated by dikes from this granite. A portion 

 of the area underlain by the Cacaquabic granite is likewise surrounded by 



«Lake Superior stratigraphy, by A. C. Lawson: Am. Geologist, Vol. Ill, 1889, pp. 320-327. 

 MON XLV— 03 20 



