Glaciers move across landforms, altering and shaping them over time. Which of the following best describes glacial erosion?
By means of abrasion, rocks that contain areas harder than the surrounding rocks form knobs which protrude out from glaciers like horns, protruding out from them like prongs of an anvil.
Glacial erosion refers to the wear-and-tear wear caused by ice erosion. Although ice itself does not do much in terms of erosion, rock fragments embedded within or breaking off of it can have significant corrosive properties that scour away at surfaces leaving behind marks called striations marks on bedrock surfaces they move over.
Abrasion typically occurs when glaciers flow downhill. As they move, glaciers collect rocks from the ground and carry them along until they reach their final destination; this process is known as plucking.
Abrasion can create beautiful landforms such as aretes, horns, moraine and drumlins. Furthermore, it produces cirques, troughs and rock basins – features that can only be seen in areas once covered by glaciers.
Meltwater can find its way under loose rocks in a glacier and disassemble them by ploughing. This process is known as ploughing.
Plucking does not involve stripping away material from the surface of rock but instead plucking out material from deep within it and transporting it away with glacial movement. Plucking erosion tends to concentrate along existing cracks in bedrock, with less effective results on soft or more tightly joined rocks than harder, open joints.
Glacial erosion can produce some amazing landforms. Ribbon lakes form when glaciers erode rocks into the shape of troughs that fill with water before eventually melting away, leaving behind ribbon-shaped lakes. Other formations created by glacial erosion include roches moutonnees – big chunks of rock that feature smooth sides covered in striations caused by abrasion – as well as pyramidal peaks formed when two corries erode back together at the summit of mountains, creating two corries and filling these troughs before eventually melting away, leaving behind ribbon-shaped lakes as their creator.
Freeze-thaw weathering (also referred to as frost shattering) is one of the primary causes of erosion in glaciated areas, producing features such as scree slopes and blockfields from rock surface erosion. Freezing/thawing releases minerals and nutrients from rocks into soil which is then essential for ecosystem processes and plant growth; additionally it also contributes to geological records by breaking down into layers that can be dated later.
Water is the primary agent of weathering, but glaciers can also play a powerful role. Glaciers erode bedrock and sediment layers underneath them to form landforms such as roche moutonnees and crags. Abrasion also occurs, but only when glacier ice has not frozen completely to its base; otherwise it would be similar to rubbing paper without embedded sandpaper over its surface – thus leading to large boulders carried by glaciers that do not result from this form of weathering but rather freeze-thaw weathering effects.
Glaciers moving down mountain sides can erode their surrounding terrain in many different ways. One such method is abrasion, in which bits of rock are dragged across bedrock surfaces and scraped away, leaving gouges, small striations marks or polished surfaces behind. Glacial erosion may also produce geomorphic structures like cirques, moraines or horns.
Rotational slip is another method of glacier erosion that occurs when sediment or rock slump blocks slide along an oil-soaked slip surface and rotate.
Rotational motion creates accumulations at the bottom of a slump and accelerates erosion rates, with freeze-thaw weathering helping this process by weakening debris through expansion and contraction of water within cracks in rocks, thus breaking it up into smaller chunks which are carried downhill by glacial flow.