What landforms are caused by erosion?

EROSION

Landscapes are under constant attack from wind, rain, ice, searing heat, oceanic waves, and flowing water loaded with rock fragments. These forces gnaw away at even the hardest rocks, in the processes known as erosion and weathering. Over time they can flatten the highest mountain ranges, carrying the rocky debris away as gravel, sand, and silt. This is deposited in the lowlands or in the sea – where, eventually, it may form new rocks.

  • SAND-BLASTING

In deserts, the wind picks up grains of sand and hurls them against bare rock, scouring the surface and widening any cracks. Deep beds of sandstone, like these in North America, may be worn into spectacular wave-like shapes, revealing layers of rock laid down over millions of years.

  • WEATHERED GRANITE

Granite is an extremely hard, crystalline rock, but it can still be broken down by erosion. It is formed deep underground, and when exposed to the air the change of pressure makes the outside layers flake away in a process called exfoliation. It can also be attacked by the acids in rainwater, and scoured by ice.

  • CLIFFS AND STACKS

Waves crashing against coastal cliffs can cut them away at a dramatic rate. The softer rock gives way first, often leaving headlands and isolated stacks of harder rock. These stacks off the Southern coast of Australia near Melbourne are known as the Twelve Apostles.

  • MESAS AND BUTTES

In arid terrain, occasional flash floods cut down through weak points in the rock to form valleys. These get wider and wider, carrying away the softer rock so the harder layers collapse. Eventually all that remains are sheer- sided mesas and smaller buttes, each protected by a cap of hard rock.

  • KARST TERRAIN

Rainwater is slightly acid, and this enables it to dissolve limestone. The result can be a landscape called karst, with heavily weathered bare rock riddled with caves. In tropical areas the rock is often eroded into spectacular pinnacles.

  • RIVER EROSION

Rivers cut V-shaped valleys and steep-sided gorges, especially where fast-flowing water carries a lot of rocky debris. The most dramatic gorges form where the land has been slowly uplifted by titanic earth movements, forcing the river to cut deeper and deeper into the landscape.

  • SLOT CANYON

Sandy water pours off high mesas during rare, but torrential desert rainstorms. It funnels through cracks in the rock at the edges of the mesas, eroding them into deep, winding slot canyons. Unlike valleys, these are often broader at the bottom than at the top.

  • VANISHED GLACIERS

In mountains and in uplands affected by the last ice age, huge glaciers grinding along the courses of former rivers scoured them out to form deep U-shaped valleys. Where the glaciers have melted, the valleys remain, often with small rivers flowing down them.

Picture Credit : Google

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