REVIEWS 415 



attempt is made to correlate the Grenville sediments south of the belt of 

 igneous rocks, with the Pontiac series north of this belt, although the 

 three possible theoretical relationships are given. 



Chapter VI deals with "Special Problems of the Timiskaming 

 Region," a brief summary of the literature together with evidences and 

 conclusions reached from a detailed study of this particular area. Con- 

 clusions are given concerning such problems as the ''Origin of Pillow Struc- 

 ture," "Origin of Ferruginous Dolomite, " "Origin of Banded Gneisses," 

 "Origin of the Cobalt Series"; a general discussion of the "Clay Belt 

 of Northern Ontario and Quebec," and the "Origin, Extent, and Dura- 

 tion of Lake Barlow and Lake O jib way." 



In chapter VII the gold, silver, and molybdenite prospects of the area 

 are described. When this report was written none of these prospects 

 was developed to the state of producing mines. The great mantle of 

 post-Glacial lake clays which cover a large part of the county makes 

 prospecting difficult. 



In a brief review of this Memoir it is impossible to give an adequate 

 summary of the many important problems of pre-Cambrian geology 

 discussed. This Memoir will be found useful to anyone interested in 

 the problems of pre-Cambrian geology of Quebec and Ontario. 



J. F. W. 



The Paleozoic Rocks of the Canton Quadrangle. By G. H. Chad wick. 

 New York State Museum Bulletin, Nos. 217, 218. Albany, 

 N.Y., 1919. Pp. 60, pis. 12, figs. 3, maps i. 

 Across the northern third of this quandrangle the Paleozoic rocks 

 form the country rock, while in the southern two-thirds they outcrop as 

 outhers among the pre-Cambrian rocks. These Paleozoic rocks are 

 tipper Cambrian and Early Ordovician in age. A section from the base 

 up is as follows: Potsdam sandstone and conglomerate (Cambrian) 

 0-150 feet, followed by a possible unconformity, then deposition of 

 white sandstone 100 ( ?) feet, Theresa dolomite and sandstone 50 feet, 

 and Heuvelton white sandstone 10-25 feet in thickness, all of which are 

 Saratogan or Ozarkian in age. The Heuvelton is followed by a dis- 

 conformity and after this period of erosion the Ordovician (Beekmantown) 

 represented by the Bucks Bridge mixed beds of dolomite and sandstone 

 50-75 feet in thickness, followed by an unconformity and above this 

 unconformity the basal 30 feet of the Ogdensburg dolomite. These 

 various formations are described in detail. The Heuvelton and all beds 

 above it are fossiliferous, but the fossils are poorly preserved. 



