Glaciers in the mountains act like nature’s bulldozers, carving and shaping landscapes with incredible force. Their movements create distinct landforms such as corries, aretes and pyramidal peaks while leaving behind features such as striations grooves and glacial polish.
Why is erosion difficult to detect?
Abrasion
As glaciers move across the landscape, they erode it by scraping. This causes landforms such as ribbon lakes, corries, and aretes to form as well as glacial polish lines and striations lines left behind from them.
Glacier ice typically contains bits of rock and sediment. As this ice rubs against bedrock, its erosion rate varies greatly from location to location and is determined by climate factors (for instance, lower temperatures can increase basal sliding rates).
Glaciers are nature’s bulldozers. They can quickly carve out U-shaped valleys and transform entire mountain ranges, even shaping distinct pyramidal peaks known as horns. Glaciers create incredible landscapes using processes including abrasion, plucking and freeze-thaw weathering; leaving fascinating landforms behind that continue to shape our world today. Learn about glacial erosion by reading up on it in our article then go outside and search for its signs!
Plucking
Glaciers are powerful geological forces that sculpt incredible landscapes while shaping Earth’s climate. Glaciers erode rock debris known as clasts by scraping against other rocks and bedrock. This erosion leaves behind some fascinating landforms including faceted clasts, striations lines, grooves and glacial polish.
Plucking is another integral aspect of glacial erosion. This process occurs when rock material within a glacier is pulled along as it slides off, scraping against rocks below like wood with each passing second until finally collapsing completely at its base.
It can create long, thin scratches in the rock beneath. Abrasion also accounts for why certain rocks feature one side smooth from abrasion and another with numerous striations from glacial action; geologists can determine which side was hit by glaciers by studying its striations pattern to reconstruct past environments and understand how glaciers changed over time. Plucking and abrasion create landforms such as U-shaped valleys, cirques and aretes as well.
Polishing
Glaciers often erode bedrock by polishing it with rock particles contained within their ice. Similar to using paper against wood surfaces, little may initially happen but with continued contact the effects can become dramatic!
This process produces the characteristic pattern of parallel scratches known as glacial striations on rock surfaces, known as glacial striations. Glacial striations is subparallel to the direction of ice flow and may extend over many meters of depth and 100s of meters across.
As with many processes in nature, erosion alone cannot account for these striking landforms; preexisting weaknesses in the rock mass also play a part.
Glacial Pavements
Glacier movement causes glacier erosion that creates dramatic landscape features such as striations lines and glacial polish. This erosion is made possible by rock debris embedded within glacier bases rubbing against bedrock surfaces like sandpaper. Abrasion rates depend on both hardness of bedrock material as well as how well fragments fit together over time, similar to pencil lead wearing down over time.
Glacier movement also erodes by plucking, with the ice scraping rocks from the ground before transporting them along its route, producing distinct landforms like corries, aretes, and drumlins as it goes.
Erosion processes have transformed landscapes over thousands of years, shaping cirques and U-shaped valleys as well as moraines and ribbon lakes. Tuolumne Meadows in Yosemite National Park was formed through glacier activity with high steep walls as a result. Nowadays glacial erratics are used in landscaping applications as rip rap on dams or shorelines as rip rap or even for road construction in North Dakota.