Remews — Dr. Dawson's Canadian Geology. 39 



and his remarks on geological mapping will be found useful features 

 in tlie volume. 



Dr. David Page has been before us many years as a teacher, and 

 he has lately been appointed Professor of Geology in the College 

 of Physical Science at Newcastle-on-Tyne. This little Outline fulfils 

 its intention as a simple guide to a general knowledge of geology. 

 The illustrations are good, and there is an absence of detail in the 

 text, in this as well as in the other work, which will, we hope, 

 stimulate the reader to inquire further into the varied and inter- 

 esting history of the Earth's Crust. 



IV. — Notes on the Post-Pliocene Geology of Canada. By J. 

 W. Dawson, LL.D., F.R.S., F.G.S., Principal of McGill 

 University, Montreal.^ 



SINCE 1855, Principal Dawson has carried on a continuous and 

 elaborate investigation of the Drift Deposit in Canada, the 

 results of which have been given to the world from time to time 

 through the medium of the " Canadian Naturalist." In all these 

 years, during which so much light has been thrown from almost 

 every side on Glacial theories. Dr. Dawson has seen no cause 

 to abandon his early conclusions on the subject, and his later 

 observations have only strengthened him in his opinions. It is 

 not surprising therefore that, his thoughts having ripened into 

 convictions, he should now wish to bring together the numerous 

 facts which have led him to consider as indisputable his explanation 

 of the glaciation of the North American continent. This he has done 

 in the important memoir before us, which is a storehouse of materials 

 not to be passed over by glacialists of every denomination, whether 

 land, marine, or a combination of both. 



There is no mistaking Dr. Dawson's colours ; he is a staunch 

 marine glacialist, who fears not to speak lightly of the " glacier 

 theory of Agassiz and others," which, according to him, " may be 

 said to have grown, till, like the imaginary glaciers themselves, it 

 overspread the earth." He smiles at the great ice-mantle imagined 

 by " stubborn land-glacialists," which " was even transferred to 

 Brazil, and employed to excavate the valley of the Amazon. But 

 this," he adds, " was its last feat, and it has recently been melting 

 away under the warmth of discussion, until it is now but a shadow 

 of its former self." 



As we have before hinted in these pages. Dr. Dawson differs con- 

 siderably from Dr. Newberry in his interpretation of the glacial 

 phenomena of North America. The views of both these authorities 

 will be best understood perhaps if we reproduce the excellent little 

 table given by Dr. Dawson (see page 40) : 



It will be seen that Dr. Dawson regards the Erie Clay (although 

 devoid of fossils) as the equivalent of the Boulder-clay and of the 

 Leda Clay of Canada. 



1 Eeprinted from the " Canadian Naturalist," new series, vol. vi., Montreal, 1872. 



