Geology and Natural History. 223 
the geology of New Hampshire. The occurrence in Allin it 
New England of Upper Silurian fossils within a few miles of the 
White Mountains, which it has made known, is a fact of the high- 
coveries are enough of themselves to prove the survey a success 
as far as geological science is concerned ; for r they are destined to 
give great aid toward dubateolliiiy the ms points in New Eng- 
land geolo 
poly the facts chia pias xe? me a shi ter on “the "pha 
lan 
eine an Eastern Vermont during Hi several ages, four of 
which are made pagar one Gd an or Primordial, and 
one Helderberg. We only remark that the author does not seem 
to have sufticiently appreciated the fact that in a region which is 
metamorphic throughout, the immense amount of denudation that 
has taken place in past time throws great doubt over all attempts 
to mark out over it outlines of the dry land of successive pre- 
Silurian ages by the bpd ig Shane distribution and positions 
of the different kinds of r 
Some other opinions in reso Hitchcock’s part of the vol- 
ume appear to us to need re 
After sete of the “ exeouniels abundant Laurentian sg 
tion” (p. 508), he observes, with regard to the origin of beds 
iron pyrites and copper fees be his “ eae rocks,” that 
“ For the fortastion en require Se a sul soe 
case of 
im 7 
could in all cases be fgets from one of n= Azo 
very lo: 
~ time which elapsed during the sold m 2,000° C, to 200° 
M. Jour. Sct.—Tuirp Seriss, Vor. IX, No. 51.—Maron, 1875, 
15 
