Glaciers alter the landscape in many ways; two of the most prevalent are abrasion and plucking.
Erosion leaves behind landforms like aretes, cirques and moraines as a result of glacier activity. Aretes are sharp crests created by glaciers on mountains. Cirques are depressions formed when glaciers carve into mountains by their movement. Finally moraines form inside and on top of glaciers.
Glaciers are powerful forces capable of dramatically changing landscapes through erosion. Erosion comes in various forms and creates distinct landforms such as roche moutonnee and ribbon lakes; it also forms rock basins, troughs and cirques characteristic of glaciated landscapes.
Glaciers commonly employ abrasion as their primary method of erosion. This occurs when glacier rocks drag across each other and bedrock below, the intensity of which depends upon both debris size and hardness of bedrock underneath.
Shape of debris also matters; sharp fragments have the ability to pierce deeper into rocks than ones with rounded points and edges, leaving grooves and striations marks in bedrock like when using sandpaper on wood, providing evidence of which direction the glacier was traveling in.
An immense glacier’s massive amount of ice plowing through the landscape typically results in picking up and carrying along smaller rock fragments called clasts, creating what are known as glacial striations patterns – long scratches that run in the direction of its movement – on rocks in its path.
These scratches are caused by another glacial erosion process known as plucking, and typically results from differences in pressure between bedrock and overlying glacier, usually as a result of differential stresses or changes in basal water pressure5. Plucking usually begins due to differences between pressure between them which could result from differential stresses or fluctuations in basal water pressure fluctuations5.
Glacial erosion creates some amazing landforms. These include ribbon lakes, corries, aretes, roche moutonnees and pyramidal peaks; as well as more distinctive landforms like crag and tail formations or U-shaped valleys and hanging valleys. So next time you head into the mountains keep an eye out for any signs of glacial erosion!
Freeze-thaw weathering breaks rocks into small fragments, which is then dislodged from glacier surfaces by the combination of abrasion and plucking processes, along with freeze-thaw cycling, through freeze-thaw cycles, which creates glaciers – creating debris flows which may carry away rock debris to be carried elsewhere – shaping landscapes while depositing minerals-rich soils.
Glacial erosion is of critical significance as it helps shape mountains and valleys across Earth’s landscape, shaping many landforms as a result. Glacial erosion also plays a part in ecosystem development and nutrient cycling as well as providing valuable insight into its geological history.
Rocks exposed to freeze-thaw weathering often feature long, parallel lines that appear as though scratched. These are known as striations and provide geologists with valuable information about how a glacier moved the rock; additionally, these crevices and cracks provide niches and habitats for various organisms.
Glacial erosion processes are responsible for many of the iconic landforms associated with glaciers, including cirques, troughs, rock basins and fjords, as well as features like roche moutonnees whalebacks and rock drumlins. They occur on decametric and hectometric scales – with larger forms like fjords occurring on kilometric scales.
Glaciers exert enormous forces when they drag over bedrock, leading to massive erosion. When passing over rocks, their passage causes wear-and-tear erosion through both abrasion and plucking; leaving behind long ridges known as “striations lines”.
Icebergs erode by freezing and thawing their bedrock, known as freeze-thaw weathering, leaving behind striations markings or corrie edges in two directions meeting up, producing what is known as an arete, which resembles Switzerland’s Matterhorn in appearance.