Glaciers are powerful agents of erosion. They erode bedrock into distinctive landforms such as striations patterns, drumlins and glacial pavements that stand out among others.
Warm-based glaciers (those without frozen bases), however, see basal sliding as a relatively slow process1,2. Because this happens so slowly, glacial erosion is hard to see firsthand!
The ice is too thick
Glaciers are powerful forces of erosion that sculpt landscapes into unique landforms through erosion and transport of material away, leaving behind corries, aretes, pyramidal peaks, U-shaped valleys, hanging valleys, truncated spurs and ribbon lakes – which you can learn more about using Vaia app’s study sets and science-backed learning modes.
A glacier’s erosion depends on its specific characteristics, like whether or not it is warm- or cold-based ice. Warm-based ice tends to erode through basal slip, which increases with speed of travel; on the other hand, cold-based ice often remains attached to bedrock and thus abrasion is less frequent.
Ice can also act as an erosional agent by plundering rocks that are difficult to erode by scraping against them and scraping over their surfaces, causing abrasion as well as creating various landforms.
The ice is too thin
Glacial erosion happens over long periods, often in remote and inaccessible locations, making it hard for humans to witness it firsthand. Furthermore, due to glaciers’ large size and slow movement patterns, distinguishing their erosional effects from concurrent fluvial erosion may prove challenging.
Glaciers erode bedrock through various methods, such as abrasion and plucking. Abrasion occurs when rock and pebbles embedded in the glacier rub against its bedrock as it passes over it; plucking occurs when frozen ice on top of broken or fractured rock pulls away chunks that had already broken away due to plucking.
Erosion forces combine to produce some incredible landforms! Examples include corries, aretes, pyramidal peaks, U-shaped valleys, cirques and ribbon lakes. Erosion can also cause features like striations moraines or truncated spurs to form.
The ice is too fast
Glacial erosion occurs when glaciers scrape away rock surface layers to erode it and move it from one location to the next, creating various landforms such as valleys, cirques, moraine or ribbed cliffs.
Glacial erosion involves two primary processes, abrasion and plucking. Abrasion occurs when rocks in a glacier rub against each other like using sandpaper on wood and scratch its surface; plucking occurs when these rocks break away from each other under their own weight, like an apple core from being plucked off a branch by hand.
Abrasion occurs most frequently under warm-based glaciers. Colder glaciers tend to remain attached to bedrock and do not produce the same effects; however, there can be exceptions; for instance in areas impacted by tectonic events where rock has softened significantly over time due to being weaker due to normal conditions; additionally abrasion becomes important where there is glacial sediment as this wears away much faster than standard bedrock and creates landforms known as “stoss-and-lee topography”.
The ice is too slow
Like rivers, glaciers can also erode the land they travel over through abrasion and plucking.
Abrasion occurs when rock fragments inside a glacier rub against rocks underneath it, scraping away bits of rock and creating striations that gives us insight into which direction the glacier was moving at the time when these striations lines were cut. Think of rubbing paper against wood surfaces: this won’t do much, while using sandpaper would cause considerable erosion.
Plumping refers to pressure melting at the base of a glacier, where ice forms around loose or weak sections of bedrock, pulling them away and carrying them along its surface by its movement – eventually reaching moraines or streams for deposit or transport downstream. This type of erosion is harder to measure and compare than fluvial rates of erosion.