J. D, Dana—Age of the Green Mountains. 199 
sion as to the probability in the case. The Crinoidal limestone 
at Bernardston is overlaid by quartzyte and fine grained mica 
schist which, since they cover a Lower Helderberg limestone 
stratum,may be metamorphic strata of the Oriskany group, 
or the lower beds of the Upper Helderberg. The similar beds 
of quartzyte and mica schist, with conformable beds of am- 
phibolyte, staurolitic mica schist, and quartzytic gneiss and 
syenyte, representing the same formation, exten 
Connecticut valley. At Littleton, 120 miles to the north, east 
of the Connecticut River, occur beds of limestone containing 
fossil corals and Brachiopods of the Upper Helderberg; and 
on the northern borders of Vermont occur corals of the same 
age at Owl’s Head,’on the borders of Lake Memphrema- 
gog. These Lower and Upper Helderberg beds were made, 
as their positions and limits show, in an arm of the sea, which 
reached from the St. Lawrence region down what is now the 
Connecticut valley, and they seem to indicate, in connection 
with other facts, that the valley was defined at an epoch not 
long preceding the Lower Helderberg, or at that of the making 
of the Green Mountains. 
V. Tue Maenirupe oF An InpivinvaL amMone Mounrarns. 
A 
ual of folded rocks. It is hence natural, in the case o 
Mountain-individual along western New England, to look for 
a breadth at least equal to that of the region which the Green 
Mountains topographically cover. The Green Mountain 
region isa northern portion of the Appalachian system and 
these views make it simply a portion in which the mountain- 
making occurred at an earlier epoch, having been hastened, as 
