REVIEWS. 
The Glacial Lake Agassiz. By WarreN UpHam. Monograph 
of the United States Geological Survey, Washington, D.C., 
1895. 
This opus magnum of one of our most active and worthy glacialists 
has fallen between the two horns of a dilemma common enough in 
the experience of the busy editor who hesitates between the hasty 
sketch which alone time permits him to prepare and the careful review 
which he knows he ought to prepare in due respect for the merits of 
the work. ‘The choice of the latter which best suits the stress of the 
hour too often proves but a renewal of the dilemma with added inten- 
sity when he next recurs to the subject, and so the struggle goes on 
until the alternative narrows to an inadequate notice or an unworthy 
negligence of a work of merit. 
This monograph of more than 650 pages, amply illustrated by 
maps and diagrams, represents several years of very industrious study 
of the surficial phenomena of the basin of the Red River of the north 
and adjacent territory, begun under the auspices of the Minnesota 
Survey and finished under those of the United States Survey with the 
co6peration of the Canadian Survey. 
The treatment is systematic and detailed. Beginning with a gen- 
eral introduction it passes to the topography of the basin which is 
minutely described, after which the underlying formations embracing 
the Archean, the two Silurians, and the Cretaceous, are discussed at 
some length. The glacial period and its drift deposits are treated 
with still more fullness because of their immediate relations to the 
history of Lake Aggasiz. This is introduced by a review of the 
glacial period in North America, and a comprehensive sketch of 
the continental ice-sheet which is illustrated by an excellent map 
showing not only the general distribution of North American Pleisto- 
cene glaciation as known at the time of its preparation, but also the 
directions of movement in various parts of the great area. Greenland 
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