Erosional Processes Flashcards
What is abrasion?
Rock fragments in the ice grind against the rock over which the ice is moving and wears away the land. (Like rough sandpaper) after it scratches the valley floor it leaves smooth, shiny rocks.
What is plucking?
Plucking is when melt water from a glacier freezes to the base rock and lumps of cracked and broken rock. When the ice advances downhill, rock is plucked from the back wall.
What is freeze-thaw weathering?
This is a type of weathering. When the temperature is above 0 degrees the water starts melting and settles into cracks in the rock and then at night the water freezes and expands by 9%. This puts pressure on the surrounding rock. As it thaws, the pressure is released. As this repeats, rocks break away and comes out of the ground where it is plucked by the glacier.
