REVIEWS 
The Geology of the Lake Superior Region. By CHARLES RICHARD 
VaN Hise and CHARLES KENNETH LEITH. United States 
Geological Survey, Monograph LII. Pp. 641; Figs. 76; Pls. 40. 
All geologists interested in pre-Cambrian geology will view with 
pleasure the appearance of this monograph. While the work is to a 
considerable extent a compilation of all other important publications on 
this region it contains much which is new and a great deal of information, 
especially on the origin of the iron ores, which here appears in print for 
the first time. The geography, general geology, bibliography, and his- 
tory of the economic development of the region are discussed in a general 
way. These discussions are followed by detailed descriptions of the 
geology of the various ore-bearing districts, the geological series, the 
glacial geology, the origin of the ores of iron and copper, a genetic classi- 
fication of the iron ores of the world, and finally by a summary of the 
geological history of the region with special mention of the unconformities 
separating the different series. 
The region covers an area of approximately 181,000 square miles of 
which the copper and the ten great iron-bearing districts combined make 
less than 3 per cent of the total. The relief varies from a maximum 
elevation of 2,230 feet above sea-level in Minnesota to a minimum of 376 
feet below sea-level in the basin of Lake Superior. 
In the section on physical geography, edited by Lawrence Martin, it 
is concluded from a discussion of the peneplaination of the area that the 
region was base-leveled in pre-Cambrian time. While the subject is 
treated from nearly all standpoints and the matter presented is good the 
reader feels that although such a statement as, “ Earlier possible pene- 
plain levels—in the Huronian for example—would have been warped or 
folded by pre-Algonkian deformation,’ appearing on p. 88, must be 
assigned to an oversight or a typographical error, great difficulty is 
experienced in distinguishing between statements which refer to the 
present peneplain and those which refer to the plain which was doubtless 
formed in the early Algonkian. Observations are made regarding the 
origin of the Lake Superior basin and the conclusion reached that it is 
largely due to graben faulting and glacial erosion. 
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