Glacial erosion occurs when glacial ice erodes bedrock, leaving behind various landforms including faceted clasts, striations lines and glacial pavements.
These features can create mountain valleys known as fjord landscapes. Other notable characteristics are circular hollow basins called cirques and ridge-like summits called aretes; and even convert V-shaped valleys created by rivers into U-shaped valleys.
Corries are amphitheatre-shaped mountainside hollows where snow accumulates year-round, often becoming compacted into ice that compacts into compacted layers that erode away at their surroundings through abrasion and plucking.
When two corries erode back towards each other they form an arete; when three or more corries converge they form pyramidal peaks which have steep sides with pointed mountains at their tips.
As glaciers move across landscapes/mountains, they erode rock to carry it along, which forms various landforms.
One such form is aretes, which are sharp mountain (alpine) formations created when multiple cirques erode against one another and collide. Aretes may take the shape of pyramidal peaks and feature long parallel lines known as striations patterns.
These striations can tell geologists the size and speed of the glacier that passed over them, providing valuable data about its movements.
Glacier-scraped rock can be an extremely powerful agent of erosion. In some instances, glaciers may even fracture or crush bedrock – this process is known as quarrying or plucking.
When two corries collide and erode backwards, they produce an arete ridge; when more than one arete forms together, a pyramidal peak may result.
Glacial erosion can create various landforms such as ribbon lakes, mountain-ridged rocks, and crag and tail formations as well as striations patterns.
U-shaped valleys are created by glaciers. This feature begins as either a V-shaped river valley, or when cirque glaciers extend downhill from an existing river valley.
Glaciers cause valley floors to erode by plucking and abrading, while they concentrate their force downwards to further devastate walls of valleys.
Erosion attacks weaker sections of bedrock more aggressively, leaving linear features such as striations and grooves visible on its surface.
Hanging valleys are subterranean valleys carved by glaciers but too cold or high for their flow to continue; as a result, these valleys remain “hanging” above their main glacial valley.
Glaciers create U-shaped valleys or fjords as they flow, filling them with debris while widening the floors and steepening the walls. Examples include Mt. Washington in New Hampshire’s North Basin and Mt. Katahdin’s and other Baxter Park peaks’ cirques in Maine.
Glacial erosion creates some of the most breathtaking landscapes. These include cirques, troughs, rock basins and fjords – which typically measure one kilometer wide – often taking advantage of weaknesses in bedrock to form staircase lakes (also called “tarns”).
These curved depressions are formed through glacial erosion processes such as plucking, abrasion and segregation of ice sheets. Furthermore, they feature steep cliff-like headwalls.
At first, it may seem hard to believe that something solid could move, but glacier ice proves this theory wrong by flowing and creating amazing landforms along its journey.
Roche Moutonnees are large chunks of rock that feature both smooth sides (known as the stoss side) and rougher, striated sides ( known as lee sides). This type of landform forms when ice erodes harder rocks more rapidly than it erodes softer ones, leading to its formation.
Glaciers erode rocks at different rates depending on the type of rock and its susceptibility to erosion, such as soft rocks which tend to erode more quickly than harder ones.
Plucking refers to the process whereby a glacier erodes soft rocks to carve a deep valley in its path – otherwise known as plucking.
As glaciers retreat, water collects in their wake. This creates long, narrow lakes known as ribbon lakes.
An ice sheet’s movement across bedrock causes it to collect particles of sand, gravel, cobbles and boulders that act like very coarse-grained sandpaper, leaving behind scores or scratches called glacial striations that indicate which direction the ice was flowing.
On the stoss side (facing toward advancing ice) of a bump, normal stresses are high and abrasion takes place, while on the lee side, where stress levels are lower, glacial plucking takes place for quarrying of rock.