Frozen in Time: A Glacial Legacy at GMF
Long before 1909, when Frederic C. Walcott and Starling W. Childs acquired the 400 acres of barren land around Tobey Pond, which would become Great Mountain Forest, other forces were at work that would shape the land in ways far more dramatic than any human intervention. Some 15,500 years ago, advancing and melting glaciers created land formations—including kettles, erratics, roche moutonnées, and glacial polish—which are visible in the forest today.
Tobey Pond, The Finest of Kettles?
Tobey Pond is an example of a kettle, formed when vast chunks of ice were buried under sediment. The melting ice left a depression in the earth, and because the water table was high enough, a pond was formed. Nearby, where the water level was marginal, a kettle bog was born. With its black spruce (likely the southernmost stand in New England), Tobey Bog is proof of this glacial activity. Where the water table is low, a land depression formed on the forest floor, as seen in the white-pine-filled depressions of the old Norfolk Downs golf course, now part of GMF.
Erratics
A hike through GMF invariably brings you to a glacial erratic. These sizable boulders are solitary reminders of the force of glacial ice, moving boulders far from home and depositing them in a new locale, often great distances away. One storied example of a GMF erratic is Meetinghouse Rock off Meekertown Road. This rock became the civic centerpiece for the town meetings held by the residents of Meekertown in the late 1700s. Here, at the house-shaped boulder, residents debated and decided on issues of their common interest. Another glacial erratic that visitors can see up close is located on Crossover Trail.
Roche Moutonnée
Despite the French moniker, roche moutonnées (sheep rock) are common in the Northeast. In GMF, several sites fall into this glacial category, most notably Wapato Lookout and a lookout off of a Crossover Trail spur.
Roche moutonnées formed in GMF when thick glacial ice from the north moved over hilly or mountainous landscapes. Rocks and debris trapped in the glacier scour the north-facing side of the rock. Often, striations in the rock provide evidence of the glacier’s path.
As the glacier descends on the other side of the peak, the force and friction of the ice begin to “pluck” rock fragments and chip away at the surface. This chipping away at the rock’s surface creates a rocky cliff or depression where water can accumulate to form a tarn or small lake. Both Wapato Pond and Crissey Pond are tarns resulting from glacial activity. Over time, Wapato Pond evolved into a wetland. However, in the 1930s, the creation of a dam allowed the pond to reassert itself to what we see today.
Glacial Polish
Glacial polish, evident on the balds of both Matterhorn and Stoneman Summit, results from a glacier scouring the bedrock clean, leaving striations in the rock behind. These striations point to the path and trajectory of the glacier. Matterhorn Summit is accessible via trail spur off Sam Yankee Trail. The Iron Trail reaches Stoneman Summit.
More information about GMF’s glacial and geologic history can be found in our May 2023 newsletter article Deep Time Under GMF and in A Fieldbook: Great Mountain Forest. Download the GMF Points of Interest Map and related descriptions from our website to explore GMF’s geologic and glacial history from its trails.
