The soils of much of South Burlington have a high clay content. These Clay soils were deposited in the standing water of Glacial Lake Vermont 12,000 years ago. Click to view larger image.clays were deposited during two periods when the area was covered by water. In the wake of the retreating ice sheet, Glacial Lake Vermont was formed from the melting water. The ice sheet formed a dam to the north, and the shores of the lake rose to over 600 feet in elevation, covering all of South Burlington.
Streams running off of the surface of the glacier as well as from the surrounding mountains carried sediments down into the lake. The airport is built on the place where the Winooski River deposited sands into the Champlain Sea. These clays help improve the fertility of South Burlington’s soils by increasing the cation exchange capacity, allowing the soil to hold more nutrients and make them available for uptake by plants and soil organisms.