Glacial erosion is a destructive landform process that creates mountain ranges and landscapes. It also alters river valleys to form parabolic cross-sections with steep sidewalls and aretes, or low spots known as canvases.
Gletschers erode rocks via two processes-abrasion and plucking. Abrasion happens when debris embedded in basal ice rubs against rocks surface like belt sander leaving scratches known as striations or grooves on their surfaces.
Movement of ice
Glaciers can erode landscapes in numerous ways, leaving telltale features on their path that can tell scientists exactly which type of glacier occupied that area and its direction of movement. These structures also serve as indicators for where their movement might have led.
Rock debris embedded within glacier ice is highly effective at erosion. It acts as an abrasive against bedrock surfaces, gradually wearing away at them until scars known as striations appear on them. Large blocks may be removed through plucking processes whereby the ice scrapes around and then drags a large rock across its floor, dislodging fragments as it goes.
Glaciers can create circular hollows in the landscape known as corries, as well as depressions in bedrock that feature steep sides on one side while having lower slopes on their opposite side, leaving chatter marks known as crescentic gouges or lunate fractures in their wake.
Glaciers pluck rocks when their ice breaks away large chunks from bedrock, using polishing (when embedded clasts in glacial ice scrape along its surface) and entrainment to pull smaller fragments along. When this occurs, glacial striations marks are left on rocks which provide geologists with valuable insights into the speed and direction of glaciers that caused them.
Glaciologists theorize that glacier’s sliding bases act like belt sanders, grinding away at mountains they cover. This phenomenon is referred to as the “glacial buzzsaw effect”. Glacial erosion plays a significant role in global sediment and biogeochemical cycles as glaciers create vast quantities of sediment that travels down rivers into oceans and eventually reach us as rivers and oceans – understanding these processes can aid our understanding of mountain development as well as climate change impacts.
Glacial abrasion occurs when rock is worn away by glacial ice moving over it, leaving behind long straight scars on bedrock surfaces called “abrasion scars”, also called striations scars or lines of wear on bedrock surfaces, that indicate which direction the glacier was moving in addition to helping identify what type of bedrock type.
Abrasion is essential in creating glacial landforms such as fjords and other deeply incised valleys and cirques which erode headward over long distances, as well as creating glacial lakes.
Glaciers’ abrasive action causes finely ground rock particles, known as rock flour, to settle at their base and deposit at its surface, acting like jewelers’ rouge to smooth and polish rock surfaces, often producing high gloss results.
So as to ensure the continuation of abrasion, this “toolkit” needs to be replenished; this may occur through various means such as being carried upward by glacier flow or washed out via meltwater runoff.
As glaciers move their massive blocks of ice over rock and sediment, they leave behind long scratches known as striations on the rock that tell geologists when that particular area was once covered by glaciers.
Glacial abrasion is widely recognized as one of the primary processes responsible for creating many characteristic glacial landforms, closely tied to both mass balance regime and thermal regime.2
Ice is not strong enough to abrade rocks due to its soft Mohs hardness of 1.5 at 0degC; rather it’s the embedded fragments which cause erosion through plucking and abrasion.
These tools range in size from microscopic crystals to meters-wide structures that span hundreds of meters long. Their shapes may resemble sickles with pointed horns that point either up the glacier or down it; their effects include crescentic gouges, rock flour and shallow grooves called striations marks that often leave behind permanent scars on bedrock surfaces; these features are sometimes known as chatter marks.