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Sedimentary Rock
Formation:• Layers of sediment are deposited at the
bottom of seas and lakes. • Over millions of years, the layers get
compressed by the layers above. • The salts that are present in the layers of
sediment start to crystallize out as the water is squeezed out. These salts help to cement the particles together.
Sedimentary Rock
Identification:• Layers of sediment, easily scraped, and
often crumble easily• Often contain fossils which are fragments
of animals or plants preserved within the rock. Only sedimentary rocks contain fossils.
Metamorphic Rock
Formation:• Earth movements can push all types of
rock deeper into the Earth. • These rocks are then subjected to
massive temperatures and pressures causing the crystalline structure and texture to change.
• They do not become liquid, but become molten.
Metamorphic Rock
Identification:• Hard rocks• Foliated bands of fused minerals• Crystalline structure with fused edges• Movement of the Earth’s lithospheric
plates cause the heating and squeezing conditions that form metamorphic rocks
Igneous Rock
Formation:• Molten rock cools and becomes solid.• Some igneous rocks form when magma
below the surface slowly cools and hardens.
• Some igneous rocks form when lava erupted from a volcano quickly cools.
Igneous Rock
Identification: • Igneous rocks contain minerals randomly
arranged in crystals. • If the rock has small crystals, this means
that it had rapidly cooled.• If the rock has large crystals, it means that
it cooled slowly deep down within the crust without ever reaching the surface.