Glacial erosion — a process in which rocks are picked up and transported — produces distinct landscape features, such as U-shaped valleys, horns and moraine.
Ice alone isn’t particularly efficient at erosion, but rocks fragments within it erode away at the rock below in various ways, producing spectacular landforms such as Germany’s Black Forest’s magnificent cirque stairways.
Freeze-thaw weathering
Freeze-thaw weathering is a mechanical process used to break apart rocks and sediment by repeatedly freezing and thawing, like cold climates or high-altitude regions with fluctuating temperatures near freezing point.
Cracked rocks caused by freeze-thaw weathering form crevices and cracks that attract various types of flora and fauna adapted to survive in harsh or unique environments.
An ELA decrease generally results in an increase in erosion rates (Figure 7a). The magnitude of this effect varies inversely with rock uplift rate; at high uplift rates, its magnitude decreases as glaciers become steeper and less sensitive to changes near ELA.
Plucking
The plucking process occurs when glacial ice comes in contact with rocks. Clasts of rock particles are pulled up by moving ice, grinding together to form long strings of grooves known as glacial striations indicating which direction the glacier moved in.
Glacial ice can also rub against rocks to cause abrasion. Abrasion has the same damaging effect as plucking but at an exponentially faster pace. Furthermore, glacial abrasion erodes the ground beneath glaciers; this process forms features like circular mountain valleys with steep sides or even horn-shaped mountain peaks when many glaciers simultaneously attack one area of a mountain.
Abrasion
Glaciers move through rock and soil surfaces, scraping away at them to form beautiful landforms as they go. Global warming has hastened glacial erosion even more and is leading to faster landform development than before.
Glacial erosion takes two primary forms. Melting and freezing causes rocks to be plucked off their bases and carried by glaciers; this also grinds away at their surfaces, further destabilizing them.
As glaciers erode mountain peaks, they deposit all the rock they remove in piles known as moraines. When multiple cirque glaciers erode a single mountain peak at once, multiple pointed shapes appear forming a pointed mountain ridge known as horns between them and form an abrupt mountain peak that stands alone as its own separate entity – another characteristic feature.
Striations
Glaciers erode rock through a process known as abrasion. Ice rubs against rocks below it like sandpaper, scraping away and grinding away as the glacier moves downhill. As it moves along its route, glacial striations scratches appear on bedrock surfaces in which its path lies; these marks indicate which direction the glacier moved in.
Glaciers also erode through mechanical weathering, loosening rocks from valley walls before depositing them as they melt – this results in unsorted rock debris known as glacial till. Additionally, any outlier rocks from outside their origin are known as glacial erratics that drop as part of this process.
Meltwater
Glacial meltwater produces a range of erosional landforms, divided into mechanical (four types) or chemical processes. Their effectiveness depends on factors like bedrock type, concentration of particles/sediment in flow rate/turbulence level of meltwater.
Mechanical glacifluvial erosion includes quarrying and abrasion. Quarrying refers to glacial flow fracturing and crushing bedrock into fragments that then end up on noncohesive beds.
Glacial abrasion occurs when glacial movement grinds and scratches the rock that it passes over, leaving behind distinctive landforms called “roche moutonnees,” also referred to as sheep rocks, which feature steeper upward slopes than their downward ones.