STRATIGRAPHY AND STRUCTURE CASTLETON AREA VERMONT

Thickness and age: The Orwell in Ira is not less than 30 feet thick and
may be thicker. Probably the absence of Orwell elsewhere in the Castleton
quadrangle is a result of erosion following the deposition of the
Orwell. The exposures at Ira may be explained as anticlinal uplifts in
the rocks of the Valley sequence that were truncated by the Taconic
overthnist. As much as 100 feet of Orwell may be found north of the
Castleton area (Cady, 1945, p. 556).
Many gastropods that appear to be Maclurites logani (Salter) are
well displayed 20 feet east of the lime quarry in the Orwell limestone.
This fossil is reported by Cady from the Orwell north of the Castleton
area. Cady assigned most of the Orwell to the lowest Trenton Rockland
stage, although it may contain beds of Lowville and Chaumont age,
i.e., Black River.
Whpple Marble
Name: The name Whipple marble is proposed to include the dark
blue-gray marble that is best exposed in a band about 2.5 miles long
extending northward along the east side of the West Rutland valley
from a point about 2 miles north of West Rutland. The northern part
of the West Rutland valley is labeled "Whipple Hollow" on the new
Proctor topographic sheet. Several inactive quarries in the type area
testify to extensive exploitation of this marble. Bain's True Blue marble
(1938, p. 10) is part of the Whipple but apparently does not include the
entire Whipple (Plate I).
Distribution: In addition to the type area the Whipple marble crops
out above the eastern West Rutland quarries and about 1 mile south of
West Rutland. Probable Whipple is associated with Orwell limestone
1.25 miles N. 50 W. of Ira Village. A narrow band of Whipple extends
from the southern boundary of the quadrangle 2 miles southwest of
Chippenhook northward to the Otter Creek Valley near Center Rutland.
A more or less parallel band of Whipple extends from a point slightly
west of Center Rutland southward to pass out of the quadrangle 1 mile
northeast of Chippenhook. A broad band of Whipple marble 3 miles
long extends northwestward from a point about 1 mile west of Florence.
On the eastern slope of Biddie Knob is a large kidney-shaped outcrop of
Whipple.
Description: The Whipple marble is a generally thin-bedded, darkblue-gray
marble containing lenses of black slate and some buff-weather-
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