Glacial Processes Flashcards
Abrasion
As the ice moves over the valley floor the jagged rocks and stones embedded at the base and sides of the glacier scrape along the valley sides and base. This acts like sandpaper, smoothing the rock below. Where the rocks embedded in the glacier scratch along the surface, striations may be left on the rock surface. Striations are scratch marks on the rock surface and they can help determine the direction of ice movement.
Plucking
As a glacier slowly travels downhill, loose rocks and stones from the valley floor and sides freeze onto the glacier. As the glacier moves down slope by gravity these rocks and stones are then torn away producing a rough, jagged surface. By tearing away huge rocks, the valley sides are left very steep and the base very flat. These rocks then become incorporated into the base and sides of the glacier and will assist with abrasion.
Freeze-Thaw Weathering
A process of erosion that happens in cold areas where ice forms. A crack in a rock can fill with water which then freezes as the temperature drops. As the ice expands, it pushes the crack apart, making it larger. When the temperature rises again, the ice melts, and the water fills the newer parts of the crack. The water freezes again as the temperature falls, and the expansion of the ice causes further expansion to the crack. This process continues until the rock breaks.
