At this point, debris that has accumulated by plucking and abrasion, has been pushed by the front edge of the ice, is driven no further and instead is deposited in an unsorted pile of sediment.
As temperatures increase, glaciers begin to retreat faster, causing more glacial till to be deposited in the form of terminal moraines.
Most of what is now Canada and northern portions of the United States were covered in ice sheets or mountain driven glaciers during the last stage of the Pleistocene Epoch.
The positioning of the lake resulted from not only subsidence, but also the terminal moraine providing the foundation for the wall that holds the water in place.
These are produced during glacial recession when boulders or blocks of ice are left in place as the glacier recedes from the newly deposited terminal moraine.
The terminal moraine is the furthest point of disturbed sediment, which is formed into a long mound outlining the front edge of the glacier.
This mound typically consists of a large quantity of rocks and boulders along with sediment, and can combine to reach a height of multiple meters.
Immediately beyond the terminal moraine is the glacial outwash plain, covered in a layer of sediment, with braided streams formed from the meltwater.
According to geologist George Frederick Wright some of the most prominent examples of terminal moraines on Long Island are "the most remarkable in the world".