Glaciers can sometimes crush and compact a boulder until it is deposited by the glacier as glacial till. Other times, glaciers pick up boulders in their paths and displace them far from their original site of origin.
Rocks and boulders that were displaced by a glacier and deposited after the glacier melted are called glacial erratics. These are quite common and are sometimes used by scientists to help determine a glacier's path. The immense force of glaciers allows them to transport and deposit enormous boulders. The world's largest boulder, which was transported by a glacier, is named "Big Rock" and weighs 16,500 tons.