Glacial erosion is one of the primary processes responsible for shaping Earth’s surface, producing landforms and landscapes by pluckeding and abrasion erosion forms.
Glaciers’ basal ice is packed with rock fragments, sediment, and debris which rumble against bedrock beneath, grinding away surface areas until there are visible grooves or scratches (known as striations marks ) left on it. This process produces visible grooves or scratches on rocks’ surfaces which leave behind distinctive features known as facets, grooves, or scratches known as striations marks ( known as striations striations striations lines ) on them.
Plucking
Glacier ice scrapes rocks against both the ground and rock surface itself, eroding both. Furthermore, this plowing action leaves long, straight grooves called glacial striations on any given surface that it moves over.
Glaciers produce vast quantities of sediment that enter rivers and oceans from mountain environments. Understanding how these deposits have formed over time is essential to understanding past and future mountain environments.
Wind erosion is one of the primary forces behind Arches National Park scenery; it carries dust and sand from place to place, often creating towering dunes. Wind also polishes rocks to produce its signature desert varnish color – commonly referred to as aeolian erosion; though this process is less powerful than glacial processes, its effects still play an essential part in shaping Earth’s surface.
Abrasion
Glaciers can erode the land they cover through abrasion, creating characteristic glacial landforms such as striations and drumlins.
Plucking and abrasion also take place beneath cold glaciers, although at relatively slower rates and likely limited to places with thin ice. Subglacial measurements show that heterogeneity of sediment leads to spatially variable deformation rates with the relatively stronger parts being the source for drumlin formation.
These processes are largely responsible for changing V-shaped valleys into U-shaped ones, such as Wales’ Nant Ffrancon Valley where narrow sides and deep bottom were created through erosion by abrasion.
Ablation
Ablation refers to processes by which glaciers lose snow and ice through melting, evaporation, calving and other means. Ablation is one of the primary forms of erosion by glaciers and plays an integral part in their flow dynamics.
Glacial erosion is responsible for creating numerous landscape features. These include roche moutonnees and whalebacks – small asymetrically-shaped hills; seracs (pinnacles of rock found in crevasse areas); striations and grooves on rocks; glacial polish (a sheen of fine-grained rock that coats bedrock surfaces); and varve couplets – layers of sediment that accumulate over time within glacial lakes.
Erosion also contributes to larger landforms, including cirques, troughs and rock basins. Due to global warming’s effect on ocean temperatures and sea level rise, erosion rates have significantly accelerated leading to rapid sea level rise affecting coastlines and ocean habitat worldwide.
Cirques
Many iconic landforms can be traced to glacial erosion. These include rock steps, fjords, U-shaped valleys and circular erosion features called cirques. Other evidence of glacial erosion includes faceted clasts, striations grooves glacial pavements rock flour (produced when rocks are abraded) and glacial polish.
Cirques are circular basins created by glaciers on steep mountain slopes. When these basins melt away, they leave behind a bedrock basin occupied by lakes. A moraine, also encasing these basins, surrounds these formations. Key to their creation is a glacier with warm-based ice that allows basal sliding and sediment evacuation while glacier tools (e.g. large boulders) cause grinding against bedrock surfaces that leads to their creation.
U-shaped Valleys
Glaciers eroding valleys can create numerous features such as striations, moraines and U-shaped valleys; as well as cirques and ribbon lakes. U-shaped valleys have steep walls at either end with a flat floor at their bases resembling an inverted “U”. When glaciers erode V shaped river-carved valleys they may also widen and deepen them further, creating new features called hanging valleys above their main valley.
Hanging valleys, also referred to as misfit streams, can often be found in mountainous regions around the world.