What are Glaciers?
Glaciers are the greatest erosional force on the planet! A glacier can erode a entire mountain to dust (over centuries of time)!
Glaciers are "rivers of ice". Glaciers are made from snow. Snow falls in the mountain valleys (Zone of Accumulation) and the snow gets deeper and heavier. The weight from the snow squeezes the snow together to become ice. The ice starts to move downhill very slowly.
As the ice moves over bumps and goes down steep drops it cracks and makes crevasses.
As the glacier moves downhill the bottom and sides of the glacier work like a huge bulldozer scraping and grinding the rock it moves over and pushing the ground up rock (glacial till) in front of it. The lateral moraines are ground up rock that is pushed up along the sides of the moving glacier.
When one glacier runs into another glacier the two glaciers become one glacier. A medial moraine is the black line that shows where one glacier has joined the other The medial moraine is made from the lateral moraines of both glaciers.
If a valley glacier flows all the way down to the ocean is called a tidewater glacier.
If the amount of snow that falls in the Zone of accumulation is greater that the amount of ice that melts in the Zone of wastage the glacier will continue to move forward.
When the glacier front (the toe) moves from land into the ocean the weight of the ice will cause the toe to break-off (calving). The ice the falls into the water are called icebergs.
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