How did glaciers affect the landscape of the US?
Glaciers are huge, slowly moving bodies of ice. The are like big bulldozers and push, capture, and entrain anything in its way. When rocks are dragged at the base of a glacier, they scrape the underlying bedrock. This creates scratches called striations and can be used to determine the direction the ice was flowing. Glaciers also create moraines which are elongated ridges of unsorted rock debris that slides off the ice, either at the front end (terminal moraine) or alongside valley walls (lateral moraines). These moraines help identify the extent that the ice advanced and can help determine periods of glacial stagnation. There are also eskers, which are ridges of sorted material that formed under the ice from flowing meltwater in ice tunnels. when glaciers stagnate in place, blocks of ice become isolated and eventually form kettle lakes. The sculpting of landscapes from glacial activity ultimately creates U shaped valleys that are deeper and wider than the stream valley that was there previously.
Glaciers are really cool!