Glaciers erode landscapes, leaving beautiful landforms behind them. But under what conditions does glacial erosion take place?
Glaciers erode by “dragging” rocks across bedrock, leaving characteristic markings known as striations on its surface. Another method involves plucking rocks from bedrock – creating nunatuk landforms that differ significantly.
1. The Sun’s Heat
Erosion occurs when rocks and soil break apart into smaller pieces and move downstream, whether due to wind, rainwater or artificial irrigation practices; wind; rainwater (both natural [rain] and artificial irrigation]); or ice erosion – which has the unique capability of creating glacial landforms on Earth’s surface.
Glaciers erode by grinding rocks against bedrock, scraping away surfaces, and creating distinctive landforms through abrasion. This form of erosion is known as abrasion and results in distinctive landforms like faceted clasts, glacial striations grooves and pavements. Glaciers also erode through plucking and freeze-thaw weathering: where melt water finds a crack in a rock and freezes it further expanding it and breaking more rock away while freeze-thaw weathering occurs when melt water seeps into small cracks then freezes off again to produce further cracks which erode further into cracks further thaw creating further cracks that further deepens this form of erosion.
The Sun is the central focus of our Solar System, and its temperatures continue to increase towards its corona, where thermonuclear fusion reactions provide our star with energy for survival. However, its true workings remain unknown.
2. The Ice’s Weight
Glaciers weigh enormously. Under its immense weight, glacier ice grinds rocks and debris against bedrock in what’s known as abrasion (similar to using sandpaper on wooden surfaces), causing erosion by scraping its surface and leaving behind landforms such as striations ridges, glacier police ridges and horns.
Glaciers often erode rocks differently depending on its hardness and softness of the underlying rocks, with soft rocks being more vulnerable. Softer rocks tend to be eroded more intensely by glaciers as their ice can grab onto and “pluck” away more of the rock surface than harder ones can. It also erodes more effectively when freezing around loose and weak sections of bedrock beneath, as this process known as plucking requires pressure melting of glacier ice at its base.
All these processes combine to form the beautiful landscape seen today on glaciated mountaintops. It includes ribbon lakes, mountain crests, aretes, cols, horns and cirques.
3. The Ice’s Shape
Glaceries don’t always erode rock evenly, depending on factors like velocity, volume, concentration of rock debris they carry along and what type of bedrock they travel over; usually softer rocks erode more rapidly than harder ones.
Glacier erosion produces a variety of unique landforms unique to glaciated landscapes. These include faceted clasts (rocks smoothed off from being pulled across by glaciers), striations and grooves, glacial pavements, rock flour and glacial polish – just to name a few!
Salzmann’s lab has achieved remarkable results through glacial erosion. First they used regular ice and then shaken it in a jar using “shear force”, turning into white powder. Next they used X-rays to observe how its molecules had aligned; the resultant material looked similar to Wurtzite; which has oxygen atoms on bonding sites between lattice points with hydrogen atoms filling spaces between lattice points.
4. The Ice’s Temperature
As glaciers advance (moving up the valley during cold seasons) or retreat (falling back down during warm ones), erosion can result. This occurs because their massive weight rubbing against bedrock surfaces produces glacial striations scratches called glacial striations scratches.
Striations form features like rock facets and grooves, while also producing rock flour to milky-looking glacial outflow rivers, as well as glacial pavements where rocks in a glacier are polished smooth by its flow.
Rates of these processes depend on the temperature of basal ice. As melting points or equilibrium line altitude (ELAs) are reached, less erosional power exists at these ELAs to erode bedrock. Therefore, during glacial-interglacial cycles areas with significant erosion migrate towards mountain range centres as climate warms.