First Children Encyclopedia

253

Worn by wind

Strong winds can

lift sand off the

ground and blast it

hard against rocks.

The rock is worn

into strange shapes.

Hills of sand

In deserts, winds blow sand

into hills called dunes. In

some deserts the dunes

stretch for hundreds

of miles, forming a

“sand sea”.

Floods

Heavy rain makes

rivers overflow,

causing floods.

Floods have

enormous power

and can wreck

buildings and

re-shape the land.

New islands

Some volcanoes

are hidden under

the sea. When they

erupt, they can give

birth to whole new

islands, like Surtsey

in Iceland (left).

Surtsey burst out

of the sea in 1963.

Shaping the land

Before flood After flood

Mount Kilauea in Hawaii.