STRATIGRAPHY AND STRUCTURE CASTLETON AREA VERMONT

Walcott (1888, p. 235) discovered Olenellus in the Cheshire (juartzite
and showed that the Cheshire is Lower Cambrian. Wolff (1891) proved
that Cambrian was thrust over Ordovician on Pine Hill in the Castleton
area.
The first comprehensive geologic investigation of the Castleton quadrangle
was undertaken by T. Nelson Dale, who published reports on the
slate belt of New York and Vermont (1899) and on Bird Mountain in
Ira (1900). For many years Dale worked in the northern Taconic area
and produced a series of reports of the highest excellence. He recognized
that the slates of the slate belt are of Cambrian and Ordovician age and
form a sequence of the same age as the Stockbridge limestone. He thought
that the Berkshire schist of the Taconic Range is late Ordovician and
that it lies stratigraphically above both the rocks of the slate belt on
the west and the carbonate rocks of the Vermont Valley on the east.
Dale's stratigraphic divisions were adopted and renamed in the Saratoga
Springs area (Cushing and Ruedemann, 1914), and these units are used
in the present study.
Keith noted the truncation of the limestone formations south of
Brandon (fig. 1) by slates surrounding the Taconic mass and concluded
(1913) that all the slate was overthrust on the carbonate rocks. Under
Keith's direction Swinnerton (1922) mapped the northwestern part of
the Castleton quadrangle. Keith's map of the north end of the Tacon
Range (1933) was rejected in toto by Kaiser (1945), who reverted t
Dale's stratigraphic divisions but accepted the Taconic overthrust an
the Lower Cambrian age of the Berkshire schist. Larrabee (1939-1940
followed Dale in the southwestern part of the Castleton area. Bait
(1931, 1934, 1938) made a careful study of the marble belt, although
his map was not published. He rejected the Taconic overthrust hypothesis
(1938, p. 14), stating that the Canajoharie slate lies unconformably
beneath the Berkshire schist. Cadv (1945) mapped much of the Champlain
Valley, and his stratigraphic succession in the carbonate rocks is
followed in this report.
Regional Physiography
The Green Mountain Range extends in a northerly direction through
central Vermont from the Massachusetts to the Canadian border. West
of the Range is a parallel lowland, the Champlain Valley, which in the
northern two-thirds of the state stretches westward to the Adirondack
Mountains. The Champlain Valley is interrupted south of Brandon by
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