How the Ice Cut This Notch — a stop on Vermont Route 100.
Look at the shape of this notch as we come through it: steep walls, a narrow floor, and a distinct U-shape rather than a V. That shape is a signature, and the thing that carved it was ice.
A river cuts a V — a narrow slot with sloping sides. A GLACIER cuts a U, because it doesn't cut down through one line, it grinds the whole valley floor and both walls at once. During the last ice age, a sheet a mile thick sat over all of Vermont, and where it funnelled through gaps in the Green Mountains it deepened and straightened them into exactly what you're driving through.
The ice left other calling cards you can spot. Erratics — boulders sitting in odd places, often a different rock from the ledge beneath them, dropped where the ice melted. Scratches and grooves on exposed bedrock, all running the same direction, gouged by stones frozen into the base of the glacier. And the till, the unsorted jumble of clay and sand and rock that makes up most Vermont soil — which is why every field here has a stone wall around it, because the ice left the stones and the farmers had to put them somewhere.
It all happened, geologically speaking, five minutes ago. The ice left maybe twelve thousand years back. These mountains have barely had time to change since.