Glaciers erode landscapes through two primary methods of erosion: plucking and abrasion.
Glacial processes produce visible evidence in glacial landforms like ribbon lakes, troughs and rock basins; however, sometimes understanding their workings is challenging.
It takes time
Glaciers are powerful erosion machines, scraping away rocks in their path with astounding force to form some of Earth’s most distinct landforms such as cirques, ribbon lakes and aretes.
Erosion occurs by two distinct means: plucking and abrasion. Plucking involves the glacier pulling along boulders or sediment clinging to it, scraping away rock underneath them much like sandpaper would; this results in long scratch marks on the rock called glacial striations patterns.
Abrasion can be more of a difficult process, requiring warm-based glacier ice in order to work. When this occurs, melting at its base allows ice particles to rub against bedrock and cause erosion, known as basal slip erosion – which forms most glaciated landscapes over time and produces amazing geomorphic features like ribbon lakes, cirques, aretes and moraine.
It’s moving fast
Glaciers use abrading to erode the bedrock beneath them, similar to how rubbing two rocks against one another might wear away wood surfaces or sandpaper, except with much harder (Moh’s hardness of 2.5) surfaces being rub against.
Glacier erosion creates geomorphic features such as glacial striations, aretes, cirques, kettle lakes, fjords and paternoster lakes – features that stand out in any landscape and make them easy to identify.
Glacial striations are grooves etched into rocks by glaciers as they pass over it, leaving behind various shapes and sizes of grooves that run parallel with their path of travel. Their depth can range anywhere from inches deep up to several feet deep, depending on the strength of the rock in which they’re found. They’re found both continentally and alpine glaciation depending on which way the snowfall flows over a region.
It’s moving slow
Glaciers use two main processes to erode landscapes: abrasion and plucking. Abrasion involves scratching bedrock as they move over it, which can leave shallow depressions that eventually fill with water to become lakes or ponds. Plucking involves pulling away at steep drainage valleys forming U-shapes or Vs and even creating knife-edge features called aretes.
Plucking occurs when glacial ice collides with rocks, and this rubbish-rub-rubbing causes bits of rock from their surfaces to rub off as they rub against each other, similar to when your fingernail rubs against paper. The erosion process resembles how your fingernail rubs against paper when writing or reading an essay.
Glaciers carry rocks of various sizes with them as they move, depositing them at various points far from where the glacier originally collected them – these deposits are known as moraine deposits.
It’s under water
Glacial erosion transforms the landscape in many different ways. From lakeshores to mountain peaks, ice erosion leaves its mark on our earth in various forms that we refer to as “glacial landforms.”
Glacier erosion occurs through two main mechanisms: abrasion and plucking. Abrasion occurs when glaciers move across bedrock and scratch it, wearing away small bits of rock in the process. Glacial erosion also leaves unique patterns known as “striations”, which demonstrate where and in what direction the glacier was moving.
As glaciers erode rocks, they can pick up fragments of rock to transport as it moves, known as plucking. Sometimes this process results in creating unusual mountain peaks known as nunatuks; or sometimes they pluck rocks off of mountains to form bowl-shaped depressions known as cirques; such landforms provide valuable clues as to their movement and behavior in past glacial cycles.