Cover: Looking southward along GrotonPond from near Stillwater Brook.
By
ROBERT A. CHRISTMAN
DEPARTMENT OF FORESTS AND PARKS
Perry H. Merrill, Director
VERMONT DEVELOPMENT COMMISSION
VERMONT GEOLOGICAL SURVEY
Charles G. Doll, State Geologist
1956
By
ROBERT A. CHRISTMAN
Geology is the study of the history of the earth as recorded in itsrocks. This study explains why certain types of rocks and minerals occurat one place and not another, why the forms of the land differ from oneregion to another, and why particular animal and plant remains aresometimes preserved as fossils in certain kinds of rocks. The professionalgeologist makes these studies his business; the amateur finds these studiesa fascinating hobby; but the uninitiated person misses much of thepleasure of travel. Anyone who notices the difference between rocks orterrains and wonders “why?”, has a potential for geology. Many fall intothis class and it is for them that this booklet has been written. It ishoped that with its aid, the traveler or vacationer may come to knowsomething about the geology of Groton State Forest. The author is confidentthat those who come into the habit of observing nature and theworld around them will find more meaning in life itself. In any case,those traveling with children may find answers to some of their questionsabout minerals, rocks and mountains.
Groton State Forest is not a geologist’s paradise—as compared toYellowstone Park or the Grand Canyon—but it does contain interestingrocks and land forms which can be explained geologically. In keepingwith the calm, subdued and mature atmosphere of the Vermont countryside,the geology is unobtrusive. There are few jutting cliffs or bare rockexposures; all is mantled with vegetation. If this vegetation could bestripped away—admittedly, a postulation that would destroy thewilderness and charm that belongs to Groton—boulders and gravellyglacial deposits would be seen to fill the valleys. If in turn these bouldersand the soil could be stripped away, a continuous floor of rock would beexposed. This would be a geologist’s paradise—square miles of bare rockwould be available for study. However, lacking the magic wand to performthis feat, we must be satisfied to glean what information we canfrom the existing rock exposures.
To use a pun, it can be said that almost all the rocks found at GrotonState Forest can be taken for granite. As well as has been determined,4all the underlying rock is granite[1] and most of the boulders deposited byglaciers of the last ice age are the same type of granite. To avoid confusionin describing these rocks, the discussion has been divided into twoparts: the first deals with the granite of the bedrock, and the seconddeals with the glaciation of the area and the deposits resulting from it. Athird section describes the geology in some of the nearby areas.