Page 35 - Super Earth Encyclopedia

FOSSILS
Some sedimentary rocks ROCK TYPES
contain the remains of living There are hundreds of different types
things that died long ago. of rock, but they can be grouped into
Most of these fossils three main types—igneous, sedimentary,
preserve bones or shells that and metamorphic. Each type of rock can
allow scientists to trace the
evolution of life. They are be turned into another by the processes
also useful for dating rocks, involved in the rock cycle.
since any rocks that contain GRANITE
the same fossils must have
been formed at the same time.

BASALT

Basalt is the most
common igneous rock on
Rain is slightly acidic in nature, the planet. It forms much
and dissolves some of the minerals of Earth’s ocean floor.
that hold rocks together. IGNEOUS ROCK
When molten magma or lava cools and turns solid,
it creates igneous rocks such as granite or basalt.
Rivers carve valleys through These are made of interlocking crystals, making them
the landscape, turning rock to very hard. They form large masses instead of layers.
smaller and smaller particles. SANDSTONE

Sand, silt, and clay particles Sandstone varies in
carried by flowing river colour from white
water are swept into the to yellow and red.
sea and carried far offshore.

LIMESTONE

Skeletons of microscopic
sea life settle on the seabed
and build up deep layers.

SEDIMENTARY ROCK
Over millions of years, soft sediments like sand or mud
are cemented together by dissolved minerals, creating
sedimentary rocks. They can be hard or soft, but always
form layers that may be folded by Earth’s forces.
MARBLE

SCHIST

UNIQUE EARTH

METAMORPHIC ROCK
Heat and pressure can change a rock’s nature in a
process called metamorphism. A soft sedimentary rock
may be transformed to hard schist, which still shows its
Soft sediments on the Compacted sediments original layers, while baked limestone turns to marble.
seabed are gradually eventually turn to hard
buried and compacted. sedimentary rock.
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