As a glacier moves across the land, it loosens and picks up rocks in its pathway. These rocks, embedded at the glacier’s base, scrape the underlying bedrock to form striations. To see how this happens, make your own mini-glacier. Cover the bottom of a small plastic container with sand, fill the container with water, then freeze until solid. Remove your glacier from its container and hold it between gloved fingers. With the sand-side down, rub the ice over a piece of soap. What happens to the surface of the soap?