Mansion_rev8.qxd - National Park Service

In addition to glaciers, the geology
of the Mansion grounds has been
shaped by the on-going force of
water erosion, transport, and deposition.
Streams and rivers have
eroded glacial till to expose
bedrock in places, while also
depositing cobbles and other sediment
from till farther upstream.
The Ottauquechee River has been
the most powerful source of such
processes and has created a floodplain
(flat land adjacent to a river),
which is (or has been) subject to
periodic flooding. The changing
volume and course of the river
over thousands of years has eroded adjoining banks of glacial
till and glacial lake-bottom sediments, and has created
features known as terraces, which record successive floodplain
levels. The Mansion is on what is probably the
uppermost floodplain terrace, with Elm Street following
the terrace edge.
On the boundary between the floodplain and adjoining
uplands, the native soils of the Mansion grounds are
characterized by two types. On the hill west of the
Mansion are the Vershire and Vershire-Dummerston
complex series derived from the glacial till. These soils
tend to be thin, coarse, loamy, and slightly acidic. Being the
uppermost floodplain terrace, the native soils along the
Mansion terrace bordering Elm Street consist of the
Windsor series derived from sandy glacial outwash. These
soils tend to be very deep, excessively drained, and acidic. 7
THE PRIMEVAL FOREST
The glacier that shaped the topography and set down
much of the soils of the Vermont Piedmont scraped away
virtually all forms of life from the region for thousands of
years. As the glacier finally retreated, the climate warmed
and seeds and nuts were carried in from the south by wind
and animals; the forests that had been forced south began
slowly to return. By about 10,000 years ago, a beech-maple
forest had taken hold on mid-elevation, cool, moist regions
such as that found around Woodstock. 8 This forest was
dominated by sugar maple and beech, with lesser numbers
of basswood, American elm, white ash, yellow birch,
Eastern hop-hornbeam, red maple, and hemlock. A
drought and a warm period in the Vermont Piedmont
about 6,000 years ago allowed an oak-chestnut forest to
take over, a forest that is today (minus the chestnuts) more
typical of southern New England and the Hudson Valley.
With the return of colder conditions roughly 4,500 years
ago, the beech-maple forest regained dominance, although
remnant oak-chestnut stands often survived on warmer,
well-drained acidic sites, such as on the hillside to the west
of the Mansion. White pine stands were also common in
the region on well-drained glacial and alluvial soils, such as
on the Ottauquechee River floodplain. 9 As recorded in the
late nineteenth century, early European settlers found such
mixed forest conditions in Woodstock:
Wherever the eye turned to survey the prospect,
there appeared an unbroken forest, stretching far
and wide till it was lost in the distance. Every valley
PRE-1789
Figure 1.3: Bedrock formations in the vicinity of the Mansion grounds.
Detail, P.H. Chang et al., “Geologic Map and Structure Sections of the
Woodstock Quadrangle, Vermont (Montpelier: Vermont Geological Survey,
c.1965), annotated by SUNY ESF. “DSs” designates Standing Pond volcanics;
“DSws” and “DSw” designate the Waits River formation.
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