Page 34 - Super Earth Encyclopedia

ROCKY PLANET

Lava erupts from Glacier ice reduces rock
Earth’s crust is made of many types volcanoes and cools to rubble, and grinds
of rock. Some are created from cooling to form volcanic some of it to powder.
igneous rocks.
Rocks attacked by ice,
molten lava or magma, while others are rain, and heat crumble
made of rock fragments that have been and form the soil in
which plants grow.
cemented together. Intense heat and
pressure can change one type of rock
to another. Meanwhile, the processes of
weathering and erosion are continually
breaking up solid rock, creating the
soft sediments that form new rock.

Some magma erupts
from volcanoes as
lava and ash, which
create volcanic cones.
THE ROCK CYCLE

Molten rock that erupts from deep
below the ground is worn away when it Magma often turns
is exposed to the weather. It is turned to solid below ground
sand and clay, which are often swept into to form igneous
the sea. Here they settle in layers that rocks like granite.
gradually harden, forming sedimentary
rock. When buried deep underground, Chemical changes
these rocks can be turned into harder make hot rock melt
rocks by the intense heat and pressure. and form magma
that seeps upwards.

Heat and pressure
transform sedimentary
rocks into harder
metamorphic rocks.

Squeezed and folded by
massive forces, rocks
are pushed up into
FAULTING AND FOLDING mountain ranges.

Where the mobile plates of Earth’s
crust collide, rock layers are squeezed
and folded by the pressure. They can
be turned on end or even upside down. Sedimentary rock buried
deep in the crust is
The rocks can also fracture, so the layers compressed and heated,
slip out of alignment along fault lines. changing its nature. The moving plates
of Earth’s crust
The largest faults form boundaries drag layers of rock
between the mobile plates, and their beneath continents.
movement causes earthquakes.

US_032-033_Rocky_planet.indd 32 01/03/17 3:46 pm