Lake Hitchcock

Anything flat in our watershed was likely lake bottom: fields, airports, brickyards and more.

Nov 08, 2025

Here’s this week’s jigsaw: Glacial Lakes and the Champlain Sea

The map above makes the best jigsaw puzzle, but this map is better for exploring: interactive, with towns, roads, and other features labeled. You can zoom into your neighborhood to see if you were part of Lake Hitchcock some 12,000 years ago. Bible literalists will quibble.

The example below covers the Hartford-to-Lebanon area. The high water mark for Lake Hitchcock is figured to be 720 feet above sea level.

A 1935 article in the Dartmouth Alumni Magazine has a nice piece mentions a handy landmark to note when imagining being underwater:

”The water line at an elevation of 657 feet would have stood 112 feet above the center of the campus so that only that part of the Baker Library tower above the middle of the clock face and the uppermost twelve feet of stonework on the College Tower would have projected above the water.”

A short summary of Lake Hitchcock

During the height of the last glacial advance, the Laurentide Ice Sheet covered Vermont and the surrounding region with ice up to a mile thick for tens of thousands of years.

About 15,000 years ago, as the Laurentide Ice Sheet began its retreat northward, meltwaters collecting behind a terminal moraine dammed the Connecticut River Valley. From Rocky Hill, CT to beyond St. Johnsbury, and extended north and west as far as Woodstock, West Fairlee and Brookfield.

This created a long, narrow glacial lake now called Lake Hitchcock. At its greatest extent it stretched from what is now northern Vermont down into Connecticut (~200–320 miles) and existed in its major form for about 3,000 to 4,000 years. The lake held silt and clay layers (varves) in annual deposit rhythms that scientists today still study for clues about deglaciation. When the dam‑moraine eroded or breached, the lake drained in stages, leaving behind the fertile valley floor, the modern river corridor, and geological evidence everywhere.

The video below is great for showing examples from present-day Connecticut River Valley: