I’m publishing a post on Glacial Lake Vermont each day for 5 straight days. These posts are part of a larger Natural History series on the evidence left behind by the glaciers.

The Evidence: Islands and lack of fossils

Looking east to the Green Mountains over Pease Mtn and Mt Philo, with water at a depth of 620′.

Islands in the deep
Only a few of our Champlain Valley hills (mountains?) would have stood above the surface of Lake Vermont. As long as the ice dam to the north was still there, the lake drained to the south at about 620′. We would expect any hill or mountain in the Champlain Valley above this elevation to be free of lake sediments. And, not surprisingly they are! So instead of varved sediments blanketing Snake Mountain or Mt Philo or Cobble Hill in Colchester we find till or exposed bedrock. To simulate the lake elevation to get a sense of what Vermont looked like you can use Google Earth (this always works to simulate flooding at whatever elevation you want to simulate)

  1. Open Google Earth desktop version (it’s free)
  2. Zoom in to somewhere in the Champlain Valley and create a polygon outlining your area of interest
  3. Set the Area Opacity under the Style/Color tab to 80%
  4. Click on the “Altitude” tab in the Properties window
  5. Set altitude to 188m (about 620ft) and Absolute.
  6. You’ll have to use a smaller polygon as larger polygons don’t follow the curve of the earth and will distort the map.

You can then use the Web Soil Survey and see how well this matches up with soil types.

Lack of fossils
As mentioned above, Glacial Lake Vermont was not a hospitable environment for life. Cold temperatures and heavy sediment load made photosynthesis nearly impossible for aquatic plants. Detritivores might find a living eating organic material washed into the lake from surrounding hillsides, and there are worm burrows retained in some sediments, but otherwise the lake sediments are remarkable devoid of fossils.

Evidence of Glacial Lake Vermont

Digging all this natural history content?

Become a monthly supporter on Patreon.

Be sure to check the archives for back issues.
And shoot me an email if you have an idea for a future blog post, newsletter issue, or podcast episode!

Subscribe to the Newsletter