68 H. C. COOKE 



by the earlier explorers, Richardson, Bell, Low, McOuat, and others. 

 The results of this work, which was all of a reconnaissance nature, 

 were published by the Geological Survey of Canada in 1903 as a 

 map entitled "A Geological Map of the Basin of the Nottaway 

 River," on a scale of ten miles to one inch. On this map, which 

 has been out of print for some years, the rocks were subdivided 

 into ''Laurentian" and "Huronian." The former group included 

 gneisses, granites, diorites and diabases; the latter schists, arkose, 

 quartzite, etc. 



The work done by M. E. Wilson, J. A. Bancroft, T. L. Tanton, 

 and the writer has since the issue of the above-mentioned map 

 resulted in a more precise mapping of the rocks of the region accord- 

 ing to their age relations. These geologists have refrained from 

 attempting the correlation of the formations described by them 

 with formations outside the limits of the region and have used local 

 names. It follows that there is at present no literature dealing with 

 the correlation of this area with others. This paper is the first to 

 deal with this problem, which is of a twofold nature. The first 

 part, which can be dealt with with some degree of certainty, is the 

 correlation of patches of formations of similar relationships within 

 the region itself; the second part, on which the evidence is much 

 more scanty, is the problem of correlating these formations with 

 others beyond the limits of the region. In the latter regard there 

 is some recent literature that has a direct bearing on the problems 

 of this region. 



The age relations of the Cobalt series of sediments have been 

 recently established by W. H. Collins. He has traced these sedi- 

 ments from the Cobalt district to the original Huronian area on the 

 north shore of Lake Huron and shown that there they overlie 

 unconformably the Bruce series, which appears to be identical with 

 the Lower Huronian of the Marquette district. As a tongue of 

 the Cobalt series projects into the southwest corner of the northern 

 Quebec area, where it overlies the older rocks with great unconform- 

 ity, this determination of Collins is of the utmost importance in 

 fixing the age of these older rocks. 



Certain ancient sediments in Ontario have been described in 

 recent years by Coleman, Miller, Colhns, and others, under the local 



