Sedimentary
Rocks
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.
Common Sedimentary Rock
Sandstone
Common Sedimentary Rock
Limestone
Metamorphic
Rocks
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:
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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.
Common Metamorphic Rock
Slate
Common Metamorphic Rock
Gneiss
Igneous
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 (magma
that has reached the surface of the Earth)
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.
Common Igneous Rocks
Granite
Common Igneous Rock
Basalt