abratsioon

Abratsioon is a term used in geology and geomorphology to describe the process of erosion caused by the grinding and scraping action of rocks and sediment carried by a glacier. As a glacier moves, it picks up and incorporates debris, ranging from fine silt to large boulders. This embedded debris acts like sandpaper, abrading the underlying bedrock and the sides of the valley.

The effect of abrasion is most noticeable on the bedrock surface, where it can polish, groove, and striate the rock. These striations, or scratch marks, are often parallel and indicate the direction of glacial movement. The debris within the glacier also becomes rounded and smoothed through this process. Finer materials, like silt and sand, are pulverized into rock flour, a very fine sediment that can discolor glacial meltwater.

Abrasion is a significant factor in shaping glaciated landscapes. It is responsible for deepening and widening valleys, creating features like cirques (bowl-shaped depressions) and U-shaped valleys. The extent of abrasion depends on the volume and speed of the glacier, as well as the hardness and type of the underlying rock. Rocks that are more resistant to erosion will show less evidence of abrasion compared to softer rock types. This erosional process is a key component of glacial erosion, alongside quarrying or plucking.