CHAPTER II. 
GLACIAL DRIFT. 
PE usin has been already made to the former existence of an 
immense thickness of ice over the whole of New Hampshire, as 
well as the entire northern portion of our continent. This ice-sheet is 
supposed to have been the natural accumulation of frozen moisture from 
the atmosphere, requiring thousands of years’ time for its gathering 
together. Like the similar glacial masses upon both poles of the earth, 
this one must have been slowly moving towards the equator, especially 
near the melting edge. A formal proof of our statement is unnecessary, . 
since the phenomena presented to us universally over the state speak for 
themselves ; and it will be difficult for any one to read an account of the 
striation and embossment of the ledges, about to be described, without 
believing in the existence of this sheet. As the subject is one of great 
interest, and sound generalizations can be drawn only from observations 
taken in every part of the state, much attention has been devoted to the 
collection of facts during the whole time of our survey. Such of these 
as are especially important will be named: hundreds of them will not 
be mentioned. Many facts belong to a class, and we need therefore 
describe with particularity only one example of them. Should the want 
of time and space prevent a full discussion of the causes inducing the 
cold climate, the method of transportation, the chronological date of the 
period, and other related topics, the reader will find an excellent sum- 
mary of conclusions of this nature in the preceding chapter. Treatises 
VOL. Ill. 23 
