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Rocks and
The Rock Cycle
• Rock is a solid material made up of
one or more minerals or other
substances, including the remains of
once-living things.
Types of Rocks
1) Igneous Rock
2) Sedimentary Rock
3) Metamorphic Rock
Igneous Rock
Igneous rock forms when
magma or lava cools and
hardens.
Igneous Intrusive Rocks are
formed from magma beneath the
surface.
gabbo
granite
pegmatite
diorite
Igneous Extrusive Rocks are
formed from lava on the surface
andesite
pumice
scoria
obsidian
Sedimentary Rock
Sedimentary rock forms when particles of rock
and other materials are pressed and stuck
together
 Erosion moves sediment from place to place
on Earth’s surface.
 Sediment is laid down in a process called
deposition.
 Slowly thick layers of sediment build up and
the weight of the layers above presses down
on the layers below. The process is call
compaction, squeezes the layers of sediment
together.
 Another process, called cementation, glues
the sediment together.
Three major types of
sedimentary rocks
1. Clastic rocks are pieces of rocks
that have been pressed and stuck
together.
siltstone
conglomerate
2. Organic rock are formed from the
remains of plants and animals.
limestone
coal
3. Chemical Rock areformed when
dissolved minerals come out of solutions
and form crystals.
iron ore
rock salt
Metamorphic Rock


Heat and great pressure deep beneath
Earth’s surface can change rock to
metamorphic rock
Sometimes heat from a volcano causes
nearby rock to become metamorphic
rock
Metamorphic Rocks
granite becomes gneiss
sandstone becomes quartzite
The Rock Cycle


Forces inside Earth and the surface
produce a rock cycle that builds,
destroys, and changes the rocks in
the crust.
The rock cycle is a series of processes on
and beneath Earth’s surface that slowly
change rocks from one kind to another.
Igneous, sedimentary, and metamorphic
rocks change continuously through the
rock cycle