GEOLOGY OF STEEPROCK LAKE. 9 



very modern look, being scarcely at all crystalline in appearance, 

 having cherty layers in grey limestone at some points and black, 

 very carbonaceous beds at others. One almost expects to discover 

 fossils in them, but none have been found.' He makes no dissent 

 from the ninefold subdivision of the series proposed by Smyth, and 

 accepts the latter's interpretation of the structure. 



Ifclnnes,' in 1899, accepts Smyth's ninefold subdivision of the 

 Steeprock series, and classifies the j-ocks of the series with the 

 Keewatin as forming the upper division of the latter; although 

 they are believed to be of later age than the great bulk of the Kee- 

 watin strata. 



In 1911, Van Hise and Leith' give a summary statement of the 

 geology of Steeprock lake, in which the Steeprock series is 

 correlated with the lower Huronian, and is said to rest unconform- 

 ably upon the Laurentian and Keewatin. But the series is said to 

 be principally exposed on the south and west shores of the lake, 

 where, as a matter of fact, the rocks are nearly all Keewatin, so that 

 it is evident that the areal disU-ibution of the series given by Smyth 

 is accepted, the unconformity upon the Keewatin being inferred 

 from the presence of Keewatin pebbles in the basal conglomerate. 

 Smyth's ninefold subdivision of the series is quoted; but ' Some of 

 the greenstones and greenstone schists included by Smyth in the 

 lower Huronian are regarded by the authors as, at least in part, 

 Keewatin.' 



During the past summer I took occasion to spend a few days 

 at Steeprock lake for the purpose of acquainting myself with some 

 of the features described by Smjrth, and for my guidance I had a 

 copy of his paper, and the map that accompanies it. As a result of 

 my visit, I am happily able to confirm the most important part of 

 his conclusions, particularly as to the existence of the series as a 

 distinct member of the Archssan, and its unconformable relation to 

 a granite-gneiss of the basement complex. On the other hand, the 

 observations that I made, while by no means exhausting the field, 

 compel me to place an interpretation upon the stratigraphy and 

 structure quite different from that of Smyth, and enable me to 

 clear up the question of the relation of the series to the Keewatin, 



p. 1-17. 



^Geological Survey, Canada, Ann. Report, Vol. X, Pt. H. 



2 The Geology of the Lake Superior Region, U.S.G.S. Mon. LII, 1911, 



