Review of Recent Oeologieal Literature. 107 
ciers on the Pacific coast, A inontli with the Muir glacier, Glaciers of 
Greenland, Ghicicrs in other parts of the world, Si^rns of glaciation. 
Boundary of the ^hiciated area in North America, Depth of ice during 
the glacial period, Terminal moraines, Glacial erosion and transpor- 
tation, Drumiins, Preglacial drainage. Drainage of the glacial period, 
Karnes, Glacial dams, lakes and water-falls. The loess, Fliglit of plants 
and aninmls during the glacial period, The cause of the ghicial period. 
The date of the glacial i)eriod Man and the glacial perio.l, with an ap- 
pendix by Warren Upham on Prol)able causes of glaciation, and 
another giving the recent observations of Mr. R. Chalmers On the gla- 
ciation of eastern Canada. The work lias 14.'> figures, maps and other il- 
lustrations, many of them new, and many from photographic views re- 
produced in "half-tone." It is faultlessly printed on heavy smooth 
paper, thus exhibiting at once in the text and in the prints of photo- 
illustrations, a creditable specimen of American publication. 
It would be impracticable to give here a digest of this book. Suflice it 
to say that the author contrives, after a simple introduction of the 
reader to a glacier, to lead him through an easy successionof steps toa 
conception of the ice-age, its signs, its results, its date, its cause, &c., 
and by a wonderful panorama of illustration, accompanied by a pan- 
oramic textual description, to give him not only an adequate concep- 
ion, but a conviction of the verity of the ice-age. To the author the 
relation of the ice age to man, and the date of his existence on the 
earth, has given zest to all his labor, and naturally the chapters wljich 
relate to the antiquity of man are specially full and complete. 
Geologists in America will welcome this excursion of the theologian 
into actual science, for they are yet prone to believe that truth to the 
mind of a theologian is as convincing as to the mind of a scientist, and 
they only wish that with a similar candor, and thoroughness all theol- 
ogians would investigate the conclusions of geology before condemning 
them. 
Specifically, while the author agrees with the majority of geologists 
in nearly all points, there are a few divergences of opinion, viz: Prof. 
Wright is disposed to regard the entire phenomena of the ice-age as 
referable to one period instead of two or more, but supposes that the ice- 
margin advanced again, and perhaps twice or thrice, after the recession 
began, the "inter-glacial" epochs being no longer perhaps than one or 
two centuries. 
As to the cause of the glacial period. Prof. Wright leaves it an open 
question. He qualifiedly rejects the eccentricity theory of Mr. Croll 
but alludes favorably to local elevation of large areas in North America 
particularly in the Mississippi valley, the Canadian highlands and the 
New England coast, though hardly allowing this to be sufficient to 
produce a glacial period. The chief obstacle to the acceptance of 
CroH's eccentricity theory is the accumulating evidence of the recent- 
ness of the last glacial epoch, though this does not interfere with Mr. 
CroU's resort to precession of the equinoxes to account for general gla- 
