Hitchcock.] 304 [March 5, 
tained a number of rarities, and was the result of several 
years’ labor in Europe. The thanks of the Section were 
voted for the gift. 
March 5, 1873. 
The President in the chair. Thirty-three members present. 
Prof. Charles H. Hitchcock spoke of his views of the 
Classification of the Rocks of New Hampshire. 
There are five great formations in this State, each of which is capa- 
ble of considerable subdivision. In the present state of knowledge 
we must use only local names for the subdivisions, and employ the 
appellations for the larger groups with considerable hesitation. Min- 
eral structure, while important, can never carry the weight of paleon- 
tological evidence. Commencing with the lowest, the following are 
- the groups. 
I. Laurentian? A. Porphyritic gneiss. B. Bethlehem gneiss. 
C. White Mountain or andalusite gneiss. D. Breccia of Franconia. 
Il. Labradorian. A. Common granite of the White Mountains. 
B. Spotted granite. C. Ossipyte. D. Dark compact labradorite. 
KE. Dark compact orthoclase. F. Red compact orthoclase. G. Reddish 
crystalline orthoclase. H. Syenites of Exeter and Tripyramid. 
Ill. Huronian. Talcose and auriferous conglomerates. Green 
schists. Whitish schists. Feldspar and tale. 
IV. Mostly Cambrian (?) A. Mica schists of Rockingham County. 
B. Merrimac group. C. Cods group. D. Clay slates. E. Green 
eranite. IF. Mt. Mote conglomerates. 
V. Paleozoic. A. Helderberg limestone. B. Clay slates. 
In order properly to understand the relative relations of these 
eroups, the Labradorian series should be first discussed. This group 
is developed most erfectly between Franconia and the Maine line 
against Conway. The several members constitute one horizontal se- 
ries of formations, the lowest resting upon the upturned edges of all 
the parts of Group I. The area may be compared to that of an iso- 
lated sea. Upon the rocky floor there seems to have been first an 
overflow of a reddish, rather coarse granite. Neither of these rocks 
