ARCHEAN GRANITES. 271 



Farther east and north on the shores of Cache Bay of Saganaga Lake 

 the relations between the granite and these sediments are shown still more 

 conclusively, if that be possible, than at the localities above referred to. 

 On the southwest side of Cache Bay, at a number of excellent exposures, 

 the granite of Saganaga Lake is overlain to the west by a beautiful typical 

 coarse basal conglomerate. This conglomerate is made up almost solely 

 of bowlders of all sizes, derived directly from the immediately adjacent 

 granite of Saganaga Lake. The matrix between these larger fragments is 

 the finer detrital material derived from the same source. 



The unconformable relations of the sediments known as the Ogishke 

 conglomerate and the Knife Lake slates, here classed as Lower Huroniau, 

 to the granite of Saganaga Lake and the Ely greenstones of this eastern por- 

 tion of the district are clearly shown by the above-stated field occurrences. 



On West Gull Lake exposures are not nearly so good nor so extensive 

 as on Saganaga Lake. Nevertheless, from a study of this area correct con- 

 clusions concerning the relations of the rocks were reached, and the later 

 study of the Saganaga Lake area merely served to emphasize their accu- 

 racy. The areal distribution of the rocks within a small part of the 

 district on the west shore of West Gull Lake is shown on the accompany- 

 ing map, fig. 17. Starting in at the granite outcrop between the two 

 meander corners at a point about one-fourth of a mile north of the southeast 

 corner of sec. 7, T. 65 N., R. 5 W., we find that the granite along the shore 

 shows its normal characters and is cut by several dikes of basic rock. As 

 we follow the exposure inland, however, the granite is found to become 

 more and more schistose, and finally we notice that this schistose rotten rock 

 is made up of small granitic fragments, with the finer granitic debris for 

 cement. Its fragmental character is most clearly shown by an occasional 

 very small fragment of jasper. In examining this exposure one can say, 

 when the extremes are seen, "Here is a granite, and here is a clastic derived 

 from the granite ; " but no sharp line of demarcation between them can be 

 drawn, for, indeed, there is no such sharp line. On the contrary, there is 

 an imperceptible gradation from the one to the other through the interme- 

 diate schistose material which probably represents the disintegrated portion 

 of the granite which was not removed by erosion. In several other places, 

 where the granite and sedimentaries come nearly together, they are sepa- 

 rated by a narrow area usually marked by a small topographic depression 



