DK - WOW! The Visual Encyclopedia of Everything

◀ 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.

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◀ 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.

Wind erosion has turned

the Coyote Buttes in

Arizona, USA, into a

natural work of art

The granite walls of

El Capitan in California,

USA, have survived millions

of years of erosion

Rock is undercut

by the waves so the

rock above collapses,

leaving a sheer cliff

Horseshoe Bend on

the Colorado River, USA, formed as

the river cut down

through uplifted rock

Moving ice loaded

with rock fragments

would have once filled this Alpine valley

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.

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