254 The American Naturalist. 
RECENT LITERATURE. 
The Canadian Ice Age.'—This volume, an octavo of 300 pages, a 
is a compilation of observations bearing upon the history of the north- 
ern half of the North American Continent during the Ice Agere | 
corded by Sir Wm. Dawson since 1855. The generalizations are not - 
extended beyond the Canadian border, but the author’s conclusions 
deny the possibility of large accumulations of land ice on an inter- 
` ior continental plain, south as well as north of the Canadian boundary. 
In fact, at that time, according to the author, there was no interior : 
plain. An ideal map of Canada during the Plistocene Age, shows - 
the northern half of the continent to consist of three large mountain- : 
ous islands, the Cordilleran, the Laurentide, and the Ap ace 
with Greenland to the north, surrounded by ice ladened seas and a 
straights, These islands were the gathering-grounds of the snow and ee 
ice that, in the form of glaciers and icebergs, were such es 
agents in modifying the topography of the continent. ee 
ment on these islands appeared to be outward in all directions from & 
central axis or plateau, analagous to what is taking place in Greenman 
at the present day. The “Terminal Moraine” of the glacialists repre 
sents the shore line of ‘the ice-ladened sea where floe-ice and bergt 
grounded with their burden of boulders and other débris. An oe 
in the levels of the so-called terminal moraine are due tod r a 
elevation. The author gives a résumé of the the present knowl | 
the glacial movements during the Plistocene period, as show? K: 
striae, and the conditions under which the Boulder-drift of Canada wa 
deposited as proofs of the above theory. mane 
The succession of deposits is treated of at length, and the we 
summarized in tables of succession and correlation. In an ase ay 
order the strata are (1) a lower boulder clay or till resting on ert | 
striated rock surface, representing shallow water deposit; $ ee 
clay, the greater part of which, from the evidence of its! 
was laid down in water from 20 to 100 fathoms deep; 
boulders. 
In regard to the striae, the 
statement as to the agents producing them: 
1 The Canadian Ice Age. Being Notes on the Plistocene Geology of Cal 
(8) surfs 
author makes the following gene a 
. and H R 
especial reference to the Life of the Period and its Climatal coe o 
the specimens in the Museum. By Sir J. Wm. Dawson. Montreal, 
The ice moye 
fossil contents 
