178 REVIEWS 



EPARCHEAN INTERVAL 



Laurentian = Fundamental gneiss, etc. 

 (Eruptive unconformity) 



f Upper Huronian 1 



. , I or Huronian proper 



Archean i | (Unconformity) I = Grenvile and 



Huronian \ r s cn ; stose pvroclastics [ Hastings series 



Lower Huronian j i- 



rr . < and eruptives 



or Keewatin ^ , , . , • 



[ [_ Coutcmchmg J 



A. B. Willmott. "The Contact of the Archean and Post-Archean in the Region 

 of the Great Lakes." Journal of Geology, Vol. XII (1904), pp. 40-42. 

 Willmott finds a step-like regularity in the contact of the Archean (pre-Cambrian 

 of the U. S. Geological Survey) and the post-Archean rocks in the region of the Great 

 Lakes, and believes it to be explained by a dislocation in the Archean before the deposi- 

 tion of the post-Archean sediments. 



A. P. Coleman. "The Northern Nickel Range." Report of the Ontario Bureau 

 of Mines, Part I (1904), pp. 192-224. With geological map. 

 Coleman describes and maps the northern nickel range of the Sudbury district of 

 Ontario. It constitutes the northern upturned edge of a synclinal of eruptive rocks 

 resting on Laurentian granites and gneisses, and including within it a little-disturbed 

 basin of Cambrian or Upper Huronian sediments and tuffs. The contact with the 

 rocks both above and below are eruptive. The eruptive grades from acid in its inner 

 margin to basic in its outer or lower margin. The nickel is concentrated or upper 

 in its basic edge. 



A. P. Low. "Report on an Exploration of the East Coast of Hudson Bay." 

 Annual Report of the Geological Survey of Canada, Vol. XIII (New Ser., 1900), 

 Part D. With geological map. 



Low describes and maps the geology of the east coast of Hudson Bay. With the 

 exception of the rocks which form the chains of islands along shore between Portland 

 promontory and Cape Jones, and also a narrow margin on part of the coast in the 

 same region, they have all been cut by granite which has not only intimately penetrated 

 them, but by its heat and pressure has so changed them to crystalline schists and gneisses 

 that only in a few places can any trace of an original sedimentary origin be found. 

 The unaltered sedimentary rocks with their associated sheets of trap and diabase bear 

 a remarkably close resemblance not only to the so-called Cambrian rocks of other parts 

 of the Labrador peninsula, but also to the iron-bearing rocks of the southern shores of 

 Lake Superior and the Animikie and Nipigon rocks to the north of Lake Superior. 

 In all likelihood they are of pre-Cambrian age and, in the opinion of the writer, are 

 the oldest known sedimentary rocks of Canada. Notwithstanding this opinion, they 

 will continue to be classed as Cambrian in order to correspond with the areas of similar 

 rocks of Labrador which have already been so classed. The series comprises from 

 the base up: Coarse arkose, banded arkose, sandstone and graywacke, chert, impreg- 

 nated with oxide of iron and red jasper, cherty carbonate, carbonaceous shales, sand- 

 stone. Included in this series are sheets or laccolites of dark-green trap. This rock 

 also flowed out to the surface. The basement rock from which this series is derived 

 has not been recognized in the region under discussion. 



