988 The American Naturalist. [December, 
vastly longer, having comprised, perhaps, between two and 
four million years, of which the Pliocene period would be a 
sixth or eighth part, thus exceeding the whole of the ensuing 
era of great epeirogenic movements and resulting glaciation. 
DivisroNs OF QUATERNARY TIME. 
The following table of the several divisions, periods and 
epochs of Quaternary time, as reviewed in this paper, is 
arranged in the descending stratigraphic order of their geo- 
logic formations. 
f Recent or Present epoch. 
Terrace epoc 
f Glacial d d hamplain epoch. 
Taie peto Glacial epoch. 
| Lafayette period f Epoch of great elevation and erosion. 
1 Lafayette epoch. 
Psychozoie division | Recent period { 
Pleistocene division 
ee eee 
