Geology is the study of the history of the earth as recorded in its
rocks. This study explains why certain types of rocks and minerals occur
at one place and not another, why the forms of the land differ from one
region to another, and why particular animal and plant remains are
sometimes preserved as fossils in certain kinds of rocks. The
professional geologist makes these studies his business; the amateur
finds these studies a fascinating hobby; but the uninitiated person
misses much of the pleasure of travel. Anyone who notices the difference
between rocks or terrains and wonders “why?”, has a potential for
geology. Many fall into this class and it is for them that this booklet
has been written. It is hoped that with its aid, the traveler or
vacationer may come to know something about the geology of Groton State
Forest. The author is confident that those who come into the habit of
observing nature and the world around them will find more meaning in
life itself. In any case, those traveling with children may find answers
to some of their questions about minerals, rocks and mountains.
Groton State Forest is not a geologist’s paradise—as compared to
Yellowstone Park or the Grand Canyon—but it does contain interesting
rocks and land forms which can be explained geologically. In keeping
with the calm, subdued and mature atmosphere of the Vermont countryside,
the geology is unobtrusive. There are few jutting cliffs or bare rock
exposures; all is mantled with vegetation. If this vegetation could be
stripped away—admittedly, a postulation that would destroy the
wilderness and charm that belongs to Groton—boulders and gravelly
glacial deposits would be seen to fill the valleys. If in turn these
boulders and the soil could be stripped away, a continuous floor of rock
would be exposed. This would be a geologist’s paradise—square miles of
bare rock would be available for study. However, lacking the magic wand
to perform this feat, we must be satisfied to glean what information we
can from the existing rock exposures.
To use a pun, it can be said that almost all the rocks found at Groton
State Forest can be taken for granite. As well as has been determined,
all the underlying rock is _granite_[1] and most of the boulders
deposited by glaciers of the last ice age are the same type of granite.
To avoid confusion in describing these rocks, the discussion has been
divided into two parts: the first deals with the granite of the bedrock,
and the second deals with the glaciation of the area and the deposits
resulting from it. A third section describes the geology in some of the
nearby areas.