Glacial erosion occurs when moving glaciers erode the land surface, often producing fascinating landforms as a result.
Glacial erosion often creates U-shaped valleys, hanging valleys, cirques, horns and aretes as its hallmark landforms; other common examples are striations fjords and glacial grooves.
Plucking is a type of erosion caused by glaciation. This phenomenon can be observed throughout the world, particularly on ice sheets formed during previous ice ages.
Plucking occurs when glaciers move down valleys, scraping rocks in these areas with their glacial feet. This causes fractures in the rock structure as well as creating long parallel lines on it that appear as though it has been scratched by something, known as striations patterns.
These striations provide geologists with vital clues as to where an ice sheet is moving, helping them pinpoint its path and the landscape it has left in its wake.
This process also contributes to the formation of rock formations known as moraines, where glaciers have advanced to their maximum reach.
As the ice melts and water pools in this area, plucking can also result in the creation of lakes near where it took place. These are typically located nearby where plucking has taken place.
Glacial plucking is an established practice in both North America and Canada, and can even be observed elsewhere where glaciers have left an imprint on the landscape.
Glacial erosion can also produce other landforms, including tarns and cirques that can be found across Norway, Finland and Sweden.
Landforms created through weathering processes typically involve plucking, abrasion and freeze-thaw weathering processes which are caused by fluctuating water pressure or changes in ice flow.
Water pressure at the bed can play an essential role in this process, as it influences how rocks break away from glaciers. If too much pressure builds up at once, rocks could possibly separate and be carried off by water currents away from its location on the glacier.
Similar to when water pressure is too low, rocks might get trapped by ice and not be expelled from their beds; thus causing plucking to occur only where ice pressure is low and not when high.
Glaciers are powerful erosional machines that move with great force down mountain sides and sculpt new landscapes by means of abrasion, plucking and freeze-thaw weathering.
Abrasion occurs when rocks frozen within the base of a glacier scrape against rocks underneath them like sandpaper, creating visible scratches known as striations in bedrock that remain visible today in glaciated landscapes.
Typically speaking, abrasion is most severe on surfaces that come into direct contact with an ice-covered rock first and last; thus leading to larger scars than smaller scratches on lee surfaces. This occurs due to how they are hit simultaneously when struck.
But abrasion can still be effective on lee surfaces with large boulders present, since glaciers can actually “pluck” these boulders from the earth as they move downhill, leaving behind long scars in bedrock that give a distinctive look to any landscape.
Abrasion can also produce valleys in glacial landscapes due to ice’s circular motion; its movement creates valleys by wearing away terrain in an undulating “U-shape”, leading to further erosion and deepening hollows into bowls known as corries.
Plucking is another type of abrasion, producing various landforms such as hanging valleys, ribbon lakes and truncated spurs. It is especially common on glaciated mountain sides where its effects can form steep-sided valleys known as glacial troughs.
Frost-thaw weathering, another form of glacial erosion, occurs when meltwater seeps into cracks in bedrock, forcing it to crack open when ice freezes over it and form breakaways when frozen again. This process creates landforms such as valleys, peaks and waterfalls not normally found within mountains.
At the height of Britain’s last ice age, glaciers formed that were capable of carving out valleys with tremendous force, leaving behind landforms such as pyramidal peaks, hanging valleys, truncated spurs, corries, and aretes that remain visible today.
Weathering is the gradual degradation of rocks and materials on exposed surfaces, such as coastlines or upland landscapes like scree slopes or blockfields.
Freeze-thaw weathering (also referred to as frost shattering) occurs when water seeps into cracks in rocks, then freezes. As it freezes, its expansion expands by around 9 percent causing enough pressure against cracks for it to burst and shatter them into jagged fragments that break apart the rock itself.
Weathering that leads to snowfall is more prevalent in places that experience cold nighttime temperatures; it occurs less often in warmer climates or Antarctica.
Upland environments often experience intense weathering that causes moraines – armchair-shaped hollowed areas formed from snow and ice accumulation that compresses downhill – to appear. These features create unique landscape features called moraines that stand out in terms of landscape features such as their armchair-shape hollowed features.
As it travels downhill, glaciers tend to pull rocks away from bedrock beneath it as it moves. This causes erosion to take place and often creates large scars on surfaces they traverse.
Water seeps into cracks in the ground and freezes, widening their dimensions while pushing apart soil particles and widening cracks further.
Under freeze-thaw weathering, pressures caused by water expansion can reach 220 MPa – sufficient to fracture certain rock types into fragments composed primarily of granitic material.
There are two primary forms of glacial erosion: abrasion and plucking. Abrasion is the most prominent form, where moving ice scrapes against bedrock below, often leaving behind large scars on its surface called “striations.”
Pluckeding is a more recent form of glacial erosion, occurring when glacial ice moves downhill and dislodges rocks from their foundation, leaving behind jagged surfaces on them that may make moving them difficult or impossible.
Glacial erosion plays a vital role in shaping landscapes, having a huge effect on both people living and working there, as well as on their ecosystem. It’s crucial that people gain an understanding of its various forms, because this could have serious repercussions both environmental and personal.
The line of glacial erosion marks a boundary that delineates between areas where glaciers acted on rocks and those where they did not. This distinction helps establish former upper limits of ice sheets where they have retreated, as well as serving to establish thickness of former ice layers which help reconstruct thermal regimes for rocks covered by them.
Glacial erosion involves many processes. These may include cracking up bedrock, abrading rock debris and being washed away by melt water; in addition, hydrological conditions like how much basal water flows can also influence its course.
Glacial erosion produces several landforms, such as hanging valleys, cirques, aretes and horns. Hanging valleys form when glacial movement pushes through spurs to form valleys oriented in the same direction of glacier movement; cirques are round glacial valleys formed from erosion while aretes are narrow ridges formed between two parallel U-shaped valleys.
Glacial erosional features often include striations grooves carved out into bedrock surfaces by tools frozen within glaciers. While they may start out small and microscopic, striations grooves can grow larger over time until becoming large enough to occupy multiple metres in depth and width.
Other glacial erosional features include scouring, which refers to the breaking apart of rock that has been pushed against mountain sides by glaciers and is commonly seen on mountain slopes that have been affected by glacier erosion worldwide. It can be found on many mountains around the world.
Stoss-and-lee topography is another glacial erosional feature influenced by jointing patterns in bedrock. It can be found both upstream of valleys where minor abrasion takes place and downstream where major quarrying takes place.
glacial erosion creates many unique landforms, including eskers, drumlins and kames. Although some of these features were present during glaciation itself, others emerged once the glaciers receded and receded back.