342 J. B. Perry on the Geology of Vermont. 
It may be remarked, in a preliminary way, that traces of 
metamorphic action are by no means so often met with i 
these rocks, as the hypothesis implies. That some portions of 
these beds have undergone changes, under the agency of heat 
both dry and moist, in connection with pressure, galvanism, 
and the like, is undoubtedly the fact. But these instances of 
metamorphism are local, and by no means such as to obscure 
the character of the whole series of rocks, or utterly destroy 
the fossil remains. 2 
With this preliminary remark we may proceed to examine 
the thickness of these formations, ‘3 
Doing this, we shall be able to see how they correspond, in 
the Talcoid Slates with Quartzites and Conglomerates to be, 
according to President Hitchcock, 1,200 feet in thickness. It 
should be added that the pebbles which go to make up the 
Conglomerate consist of Gneiss, of Schist, and fragments of 
other rocks, which, perhaps, belong to a pre-sedimentary age. 
The thickness of the Stockbridge Limestone may be well esti- 
mated in Danby Mountain, more recently known as Mount 
Eolus. These calcareous beds, varying little in that locality 
from a horizontal position, are overlaid by Lower Taconic 
Slate, and so situated as to preclude all probability of repett- 
tion. The thickness of this single mass of limestone is be- 
tween 1,900 and 2,000 feet. The overlying Talcoid Slate may 
be better seen in a single mass, and its amount more correctly 
estimated, in Berkshire county, Massachusetts, than in Ver 
monf. Graylock is made up of immense beds of this slate, 
overlying the Stockbridge Limestone, and having the success- 
ive layers only slightly inclined. Their entire thickness 8 
2,000 feet. We thus have more than 5,000 feet of rocks 
exhibited in Swanton in great force. They dip from 30° 1?- 
et toward the east, show no indications of any repetitions 
t 
as less than 10,000 to 15,000 feet in thickness 
ony y this series of rocks in various 
hat this est- 
ther words, 
ing to the Lower Taconic, as overlying its W 
a a a i 
th f . 
2 "pwr Aching succeeding the Swanton Group, and a8 
