EROSION

 The granite walls of E1 Capitan in California,USA, have survived millions of years of 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.

WEATHERED

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 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.

RIVER EROSION

Rivers cut V-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 the earth movements, forcing the river to cut deeper and deeper into the landscape.

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 tremains are sheersided  mesas and smaller buttes, each protected by a cup 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