CLIMATE AND PHYSICAL CONDITIONS OF KEEWATIN Ii 



tions also graphitic slate, rusty weathering dolomite, and a coarse 

 fragmental series accompanying typical iron range rocks. He 

 suggests that the fragmental rocks may imply a break in the Kee- 

 watin, and quotes Miller and Brock as favoring this view. 1 



Morley E. Wilson briefly describes similar rocks from the 

 Temiscaming region to the south as follows: "On the north shore 

 of Larder Lake there is a belt — nearly a mile wide — of interbanded 

 phyllites, slates, and graywackes, which parallels the lake shore 

 for several miles. These rocks have a nearly vertical attitude; 

 a uniform northeasterly strike ; are in places graphitic ; and locally 

 contain small quantities of iron ore formation." 2 



From the citations given above it will be seen that sedimentary 

 rocks like the Couchiching or the Grenville series are widely spread 

 in the Keewatin of Ontario. They often cover large areas and in 

 many places equal or surpass the eruptives in extent. It is true 

 that there are large gaps where no ordinary Keewatin sediments 

 are known to exist, but doubtless many small areas remain undis- 

 covered because unlooked for. A few years ago no one could have 

 foretold that the iron formation would be found in almost every 

 Keewatin area in Ontario, but we now know that this is the case. 



The Keewatin sediments can no longer be overlooked as neg- 

 ligible in any account of the Canadian Archaean. In reality 

 these sedimentary rocks are the true Keewatin, and the accom- 

 panying eruptives and ash rocks must be considered less impor- 

 tant, in a sense accidental, members of the series. 



The Keewatin of the states near Lake Superior seems from the 

 published accounts to contain a much smaller proportion of sedi- 

 mentary materials than of volcanics; which no doubt accounts 

 for the prevalent opinion among American geologists that the Kee- 

 watin, or the older part of the basal complex, consists essentially 

 of eruptive rocks. 



RELATIONS OF THE KEEWATIN TO THE GRENVILLE SERIES 



Having shown that the Keewatin contains sedimentary rocks 

 of every kind, some of them having a wide extent and a great 

 thickness, it is natural to compare them with the ancient sedi- 



l Bur. Mines (1909), 275-78. 2 Smn. Rep., Geol. Stir. (1909), 175. 



