STRATIGRAPHY AND STRUCTURE CASTLETON AREA VERMONT

We are therefore faced with the unwelcome necessity of looking for
the root zone in or east of the Connecticut Valley region. A satisfactory
correlation between the New Hampshire and Vermont stratigraphy
across the Connecticut Valley may bring to light evidence on the Taconic
roots. If the Taconic rocks originated in the Connecticut Valley region,
the net slip along the thrust must be at least 50 or 60 miles. Although
Alpine geologists may view with complacency such displacements, the
tendency in New England has been either to deny that the Taconic
sequence is allochthonous or to deny that it has roots.
It should not be forgotten in a discussion of the main Taconic klippe
that the depositional basin must have been at least 100 miles long and,
in some places, 40 miles wide. An eastern root zone must therefore show
a discontinuity along a distance of at least 100 miles. If the slate sequence
south of the St. Lawrence River and certain rocks lying on the Martinsburg
shale of Pennsylvania (Kay, 1941; Stose, 1946) are integral parts
of the Taconic sequence, we must infer a basin extending at least from
Maryland to the Gaspe Peninsula and located parallel to but east of the
basin in which the Appalachian Valley carbonate sediments were deposited.
Kay (1937, p. 290) has called this eastern basin the Magog
Trough and the western basin the Champlain Trough. We need not infer
a barrier between the two basins, however.
MINOR FEATURES
Cleavage
The dominant foliation in all the argillaceous rocks of the Castleton
area is an axial plane cleavage inclined 15-75 degrees east. The cleavage
of the Taconic Range has a generally lower dip than that of the slate
belt to the west. This foliation is usually similar to or coincident with
the bedding of the argillaceous rocks. Such relations may be proved in
large quarries, where the cleavage is parallel to the axial planes of the
folds. It is a flow cleavage due to the parallel orientation of component
mineral particles, chiefly the micas, and the cleavage planes are assumed
to be perpendicular to the least strain axis of the strain ellipsoid. The
inclination of the cleavage is attributed to a couple, a superficial westward-directed
force together with a retarding drag beneath. Probably
the foliation was originally developed at steeper angles and was overturned
westward with continued application of orogenic stress.
Fracture cleavage is in places present together with flow cleavage
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