No, 161.] 
113 
cient volcanic action; not that there are volcanic craters, but the 
phenomena of dykes and the character of the mineral matter, both 
as it exists in the rocks and imbedded minerals, belong to those of 
a volcanic district. Another phenomenon, which, if established, 
goes still farther to support this view^, is, that earthquakes are yet 
of frequent occurrence in this neighborhood. This is the prevail- 
ing opinion among a class of inhabitants who have resided here 
for many years. We do not wish to commit ourselves on this 
point until farther inquiries are made, for tliere is a great liability 
to deception in this region, from concussions of the earth by falling 
rocks and slides — still there is ground to believe in the prevalent 
opinion, that earthquakes do yet occur in this region. 
The other primitive rocks of the northern counties are gneiss, 
hornblende and granular limestone. The talcose and mica slates 
rarely occur, and when they do, are quite limited in extent. — ■ 
The absence of these slates, and the great preponderance of horn- 
blende and granular limestone, give to this region some peculiar 
characters. There are none of the coarser granite in veins and 
beds, as in the primitive parts of New-England. There is a dif- 
ference also in the simple minerals, so that a slight examination 
suffices to enable us to point out their localities. 
As it is not so much our intention or business now to give a 
mineralogical description of these rocks, as to relate their mode 
of occurrence and their geographical extent, we shall proceed at 
once to speak of their respective relations. 
We take gneiss, hornblende and granular limestone together, 
and say of them generally, that we found them to form alter- 
nating strata, with a dip to the west and southwest, but in the 
more northern parts the dip changes towards the northwest. The 
value of the dip, in degrees, varies from 40° to 80°. The mean 
line of bearing of these rocks is northeast and southwest. Com- 
mencing an exploration of these strata at the eastern edge of the 
sandstone in Theresa, near the falls, and proceeding east, we 
should pass over the out-cropping edges of these rocks, until we 
come into the neighborhood of Keene, near Whiteface, in Essex 
county. We have then obtained the anticlinal ridge. The valleys, 
as well as the ridges, through the whole r^ute from Theresa to 
the anticlinal ridge, are primitive, and their dip is westerly. It is 
however worthy of remark, that on this sectional line gneiss often 
loses its essential character, and becomes strictly granite; that is, 
lAssem. No. 161.] 15 
