Erosional feature of running water and wind

Running water

Erosional work of a river is done by hydraulic action, abrasion, attrition and solution. Features:

• V-shaped valley: formed by vertical (downward) cutting in the youth stage, in the hills.
• Gorge and canyon: deep, narrow valley in hard rock, e.g. the Kali Gandaki gorge.
• Waterfall and rapids: form where hard rock lies over soft rock; a plunge pool forms at the base.
• Potholes: circular holes drilled in the bed by swirling pebbles.
• River terraces: step-like old floodplain levels left after the river cuts down again.
• Meanders and ox-bow lakes: formed by lateral (side) cutting in the old stage.
• Interlocking spurs: ridges of the valley sides that project alternately into the winding valley of a young river.

Wind

• Deflation hollows (blowouts): wind lifts loose fine particles and lowers the ground, e.g. the Qattara depression.
• Mushroom (pedestal) rocks: wind-blown sand abrades the base of a rock more than its top.
• Yardangs: streamlined ridges of rock parallel to the wind.
• Ventifacts: pebbles with polished, flat faces cut by sand blast.
• Zeugen: tabular ridges of hard rock over softer layers.
• Desert pavement: gravel left after fine particles are blown away.
• Inselbergs: isolated residual hills.