12 A. P. COLEMAN 



mentary rocks of the Grenville and Hastings series of southern 

 and eastern Ontario and Quebec. These were studied long ago 

 and were originally included in the Lauren tian; though now the 

 term Laurentian is confined to the eruptive granites and gneisses 

 which penetrate them and rise from beneath them. 



The nearest Grenville rocks to the Keewatin sediments described 

 above begin about 150 miles south of the Larder Lake region in 

 the township of Loring, just south of Lake Nipissing, where gra- 

 phitic schist occurs. Between this and Parry Sound crystalline 

 limestone and gray garnetiferous schists and gneisses are widely 

 found and were compared by myself in 1900 with the western 

 Couchiching. 1 There are also green schists in the region suggest- 

 ing western Keewatin schist of eiuptive origin. 



In eastern Ontario the Grenville and Hastings series often 

 greatly resemble the Keewatin, including banded silica and iron 

 ore, slate, quartzite, and fine-grained gray sedimentary gneiss con- 

 taining graphite. There are, however, some marked differences. 

 Limestones are rare in the western Keewatin but make the most 

 prominent rock in the Grenville and Hastings series, even reaching 

 a thickness of more than 50,000 feet, according to Adams; while 

 volcanic rocks play a larger part in the west than in the east. Just 

 how the eastern Archaean is related to the western is still a matter 

 of discussion, Adams thinking that the Grenville and Hastings 

 series are both probably the equivalent of the western Huronian, 

 while Miller believes that the Hastings series represents the Huro- 

 nian, and the Grenville series the Keewatin. 



From my own observations it may be said that a considerable 

 part of the Grenville rocks are closely like the western Keewatin. 

 If they were found in the Upper Lakes region they would certainly 

 be classed on lithological grounds as Keewatin ; and the two series 

 of rocks are also related in the same way to the Laurentian batho- 

 liths. In the east as well as in the west these great eruptive masses 

 are later than the overlying rocks and have pushed up through 

 them, often nipping them in as synclines. In neither case has the 

 foundation on which these earliest sediments were laid down been 

 preserved. 



z Btir. Mines (1900), 169; also 182. 



