STRATIGRAPHY AND STRUCTURE CASTLETON AREA VERMONT

2- or 3-inch quartzite layers interbedded with dolomite, and near the
top at least one 5-foot quartzite. This upper member is not easily distinguished
from the lower Danby; on no basis was it possible to map the
Wallingford separately in the field. The Danby formation is therefore
treated as a unit.
Thickness: The Winooski-Danby boundary is placed at the first
appearance of quartzite. In other respects no lithologic break is noted.
The top of the Danby is placed at the lowermost uniform gray dolomite
of the Clarendon Springs. Between these limits the Danby regularly has
a thickness of approximately 700 feet in this area. Westward at White-
11, New York, probable Danby equivalents are approximately 350 feet
ick, and "close to the Adirondacks the thickness may be considerably
s" (Rodgers, 1937, p. 1575).
Age: The Theresa formation at Whitehall, New York, considered
(Cady, 1945, p. 536) to represent the Wallingford member, is basal
Franconian (Rodgers, 1937, p. 1575). The upper Danby is therefore
Franconian, and the lower part, equivalent to the Potsdam sandstone.
is presumably Dreshach."
Clarendon Springs Dolomite
Name: The gray dolomite lying between sandy dolomite and white
marble was named by Keith (1932, p. 397) from exposures at Clarendon
Surings, Vermont.
Distribution: The Clarendon Springs dolomite crops out in two large
V-shaped patterns, one opening northward and the other southward.
The eastern limbs of the V's are incomplete because of faulting. The apex
of the northern V is in the Otter Creek lowland 1.5 miles northwest of
Center Rutland. From this point the Clarendon Springs dolomite extends
northwestward through Proctor to the northern border of the quadrangle
and northeastward toward the crest of Pine Hill. The southern V-shaped
outcrop has its apex on the western slope of Boardman Hill. From there
the rock crops out in a narrow band trending southward to the boundary
of the Pawlet quadrangle and in another band trending southeastward
and ending 3/ mile west of Flat Rock.
Description: The Clarendon Springs dolomite is a distinctive lithologic
unit made up of uniform, massive, iron-gray dolomite that weathers
light-gray or white. In thin section it is composed of a tough aggregate
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