But when millions of snowflakes are packed together and start to move as a sheet of ice, it creates a glacier one of the biggest Earth movers. They are found on tall mountains or as giant sheets of ice in the polar regions. Glaciers are made as layer after layer of snowflakes build up. The air is squeezed out of the crystals, causing dense blue crystals of ice. The weight of the ice causes crystals to glide over one another, pushing the glacier outward.
Glaciers also move by sliding along on meltwater that forms under the ice.
Activities Make a mini-glacier. You ll need a metal cookie sheet, an empty yogurt container, ice cubes, waxed paper, and a cup of sand. Rub an ice cube over the cookie sheet to make it wet and then stick a piece of waxed paper onto the cookie sheet. Hold a fresh ice cube at the top of the cookie sheet. This is your mini-glacier.