Rocks & Landforms I-7 Notes

Glaciers A large mass of ice on the land surface which moves by flowing under its own weight Forms over a very long period of years whenever there is so much snow in winter that not all of it melts during the summer.

Valley glaciers form in high mountains and flow down valleys like “rivers of ice.”

Ice sheets or ice caps Larger glaciers Form over large areas of land and flow outward from the highest part of the ice mass Can cover almost all of a continent (Antarctica-largest glacier)

Terminus – the front of a glacier

Advance and Retreat of a Glacier Glaciers will advance if snowfall is high and melting is low A glacier will become smaller in volume (retreat), when snowfall is less and melting is greater. The ice of the glacier is always moving toward the terminus even though the terminus is shifting slowly backward.

Glacial Sediment and Landforms

Landforms Glaciers may freeze solid to the bedrock or slide along bedrock eroding the bedrock carrying enormous amounts of material (ranging from clay to gigantic boulders)

Moraine or end moraine Ridge of glacial sediment formed when the terminus of a glacier stays in the same place for a long period (many years)

During the warm season, streams of water are produced by melting of glacier ice and snow. This is called glacial meltwater Meltwater streams carry glacial sand and gravel for long distances before depositing it in river valleys