A glacier is a large ice cap that moves down the sides of a mountain, spreading out in all directions. Most glaciers are small and form on the sides of high mountains. These are called valley glaciers. They move down valleys that have already been cut by rivers. These ice flows will cut the river valleys into a U-shaped valley that can be seen after the glacier melts.

Receding glaciers leave piles of rock on their edges called medial moraines. Moraines are exposed as major landforms that identify where the glaciers once were. Terminal moraines are mounds where a glacier stopped and began to recede. 

Glaciers leave a variety of geologic formations behind long after the ice has melted. Drumlins are low, oval mounds of compacted boulder clay molded by the glacier. Eskers are ridges of gravel and other sediments deposited by glacier meltwater. Kettle lakes are depressions left from huge ice blocks that calved (or broke) off the front of the glacier and became embedded. After the blocks melt, the depressions often fill with water and become lakes. Kames are steep-sided mounds of sand and gravel deposited by the melting glacier ice.