Perry.] 54 [February 28, 
thus as being for some such reason distinguished from, and superior 
to, other similar periods of time. 
As to the nomenclature adopted by Professor Dana for the desig- 
nation of the divisions of the Post-Tertiary, a few words may not 
be out of place. The first term, “ Glacial,” ++o such as admit that 
the agency of ice was predominant during the period under consid- 
eration must seem comparatively free from objection. It being con- 
venient, as well as characteristic, we may adopt it with advantage. 
The second, or “Champlain,” is preoccupied, it having been 
employed by the New York geologists as descriptive of a series of 
formations lying along the border of Lake Champlain, at the time of 
its adoption generally supposed, and now well known for the most 
part to answer to the original Cambrian, or Lower Silurian of Eng- 
land and Wales. To the third term, “Terrace,” some are likely to 
take exception, since the terraces are the result of several different 
processes, and really belong to successive stages of action. On the 
whole, however, it isa good name, and may be adopted with advan- 
tage. Meanwhile a careful study of the monuments of the time thus 
designated, and so of the agencies operative during its continuance, 
in portions of New England which were not subject at least to the 
action of the sea, and which are favorable to the discrimination of 
differences, has suggested several minor divisions, and the employ- 
ment of the word in a sense more restricted than that implied in Mr. 
Dana’s “ Terrace epoch.” ‘The recognition of these smaller sections 
of geologic time is of moment, insomuch as they are calculated to 
show more distinctly the steps of progress characteristic of the 
period. Their recognition is also of importance, since, if they be 
investigated in detail, they are able to throw light on preceding 
periods, which, as more remote, cannot be, in most instances, studied 
in all their minutie to so great advantage. 
The relation of this classification to that of Sir Charles Lyell, 
should receive a moment’s notice, especially as the latter is famil- 
iarly known, and has been widely adopted, in this country. Mr. 
Lyell’s divisions are, (1) Plistocene ( == Newer Pliocene), (2) Post- 
Pliocene, and (3) Recent. His Plistocene includes the Drift or 
Glacial deposit, and the superimposed stratified beds; it thus an- 
swers exactly, or very nearly, to the Glacial and Champlain of Prof. 
Dana. Accordingly the last-named writer has only one period, 
1 This term as applied to the time in question, was first used by Professor 
Agassiz in 1840. See his paper, ‘“‘On the Ice Period.” 
