ON THE LAKE SUPERIOR REGION ioi 



it is also entirely possible that the relations are due to faulting or to 

 both unconformity and faulting. 



Four miles east of Thessalon on several islands off the coast is a 

 great conglomerate, mapped by Logan and Murray as gray quartzite. 

 This conglomerate was found to rest unconformably upon the granite, 

 the actual contact being observed upon one island opposite the north- 

 west quarter of Sec. 12 of the Township of Thessalon. The frag- 

 ments in the conglomerate are well rounded and are largely granite, 

 but there are also numerous pebbles and bowlders of greenstone and 

 green schist. On several islands adjacent to the conglomerate the 

 massive granite includes many fragments of greenstone and green 

 schist, showing the granite to be intrusive into a greenstone formation. 

 Thus in the complex against which the conglomerate rests we have a 

 source both for the granite and greenstone pebbles and bowlders. 

 To the northwest the conglomerate grades up by interstratification 

 into a quartzite. About a quarter of a mile west of the conglomerate, 

 near the north end of a point, the quartzite is found to become a fine 

 conglomerate, and to rest against greenstone which is cut by a large 

 granite dike. The greenstone shows ellipsoidal parting. The 

 granite dike strikes toward the conglomerate and the quartzite, but 

 it dies out into a depression showing no rock, which continues to 

 the quartzite some fifty or sixty feet distant. The quartzite and 

 conglomerate strike directly across this depression, showing con- 

 tinuous exposures, and are not cut by granite. The relations here 

 are believed by certain members of the party to show clearly that 

 the quartzite and conglomerate rest unconformably upon the green- 

 stone, but other members felt that this conclusion is not certain. 

 The conglomerate and gray quartzite are cut by greenstone dikes. 

 Similar rocks also cut the Thessalon series referred to below. 



The rocks called green chloritic schist by Logan (3c) will here be 

 called the Thessalon series. This series consists of ellipsoidal green- 

 stones, amygdaloids, agglomerates, and massive greenstones. No 

 undoubted sediments were observed in the series. The relations 

 of the Thessalon series to the granite were observed southeast of Little 

 Rapids, and it was found that the granite cuts the greenstone series 

 in an intricate fashion. The belt of gray quartzite, mapped as 

 extending inland for a number of miles between the Thessalon series 



