Ice is an extremely powerful force, creating some astonishing landforms along its path. Let’s examine some types of glacial erosion and their features as we examine some examples of glacial erosion.
Glacial environments experience two forms of erosion: abrasion and plucking. Abrasion happens when glacier debris scrapes against rocks’ surfaces, gradually polishing and smoothing out their surfaces over time.
Abrasion
Ice is an incredibly powerful force, capable of altering landscapes through erosion processes. Through these erosion processes, glaciers create unique landforms such as corries, aretes, pyramidal peaks, ribbon lakes and moutonnees (rocky mountain ridges), among many others.
But, rates of abrasion and quarrying differ substantially and cannot be explained solely by subglacial friction; this has implications for understanding glacier flow.
Plucking
Plucking, a type of glacial erosion, is especially devastating to large blocks of rock – known as “joint blocks” in bedrock – where valley glaciers freeze to infiltrate cracks or joints within it.
Fluctuating water pressures within cavities and cracks alter the effective ice pressure on the bed, enabling overriding ice to dislodge and plough through this obstruction.
Freeze-thaw weathering
Freeze-thaw weathering refers to the process by which rocks are broken down by cycles of freezing and thawing, releasing minerals and nutrients that allow plants to absorb them directly from the environment.
Landforms like ribbon lakes and pyramidal peaks may result from glacier action. Other striking landforms created by glaciers’ erosion of different areas of rock include aretes and truncated spurs – two features created when two corries eroding back-to-back create aretes while glaciers create interlocking spurs to form steep hills with sharp edges known as aretes and truncated spurs respectively.
Ribbon lakes
Ribbon lakes can be found in glacial valleys. They form when glacier ice flows over soft rock that erodes more readily than harder rocks higher up in the valley, creating long and narrow bodies of water reminiscent of ribbons.
Glacial erosion can produce many distinctive landforms, such as corries, aretes, pyramidal peaks, U-shaped valleys, hanging valleys, truncated spurs and ribbon lakes. Moraine may also form part of these landforms through processes like abrasion and plucking erosion processes.
Aretes
Glacerial erosion processes such as abrasion and plucking can leave distinctive marks in a landscape, known as landforms. Landforms include ribbon lakes, aretes, pyramidal peaks, U-shaped valleys, hanging valleys, truncated spurs, and crag and tail features.
Aretes are narrow ridges of rock that form between adjacent glacial cirques or valleys. They are often found in mountainous regions where there is significant glaciation.
Pyramidal peaks
As glaciers progress through valleys, they erode away at their sides, creating hanging valleys which may then form waterfalls post-glacially.
Where two corries erode back-to-back, it can create aretes – knife-edge ridges. Additionally, this may create pyramidal peaks – steep-sided pointed mountain peaks such as Switzerland’s Matterhorn.
Nunataks are formed when two or more aretes come together at one spot, known as nunataks.
U-shaped valleys
U-shaped valleys (also referred to as glacial valleys or glacial troughs) are characteristic of mountain glaciation. They typically feature steep sides and an even floor surface.
As valley glaciers move downward, they erode the land they pass over, leaving behind distinct features such as fjords and U-shaped valleys as well as ribbon lakes and aretes as they do so – testament to their immense power! These characteristics demonstrate just how amazing glaciers truly are!
Hanging valleys
As glaciers move through landscapes, they form specific landforms such as corries, aretes, pyramidal peaks, U-shaped valleys, hanging valleys, ribbon lakes and truncated spurs.
Hanging valleys are side valleys left ‘hanging’ above their main valley due to more rapid erosion in its main body than on its tributary glacier; often creating spectacular waterfalls in their path.
Truncated spurs
As glaciers move downhill they come into contact with rocks and start to wear away at them through what is known as abrasion.
A glacier acts like an enormous bulldozer, moving and clearing soil while breaking apart interlocking spurs to form shorter ones – effectively truncating them.
This process leaves behind features such as corries, aretes, pyramidal peaks, ribbon lakes and glacial troughs – features that form very distinctive landscapes.
Crag and tails
Crag and Tail Landforms can be found all around the world and consist of two landform elements – a steep rock face (crag) connected by an undulating ridge of unconsolidated material (tail). They’re an example of glacial landforms found all across our planet.
Horned crag-and-tails form when subglacial events come together in a specific sequence: basal melting with frozen patches followed by refreezing of the bed surface. Their unique morphology provides clues as to ice flow patterns.