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The Rock Cycle
How can this be a cycle?
• What rock forms when magma cools?
– igneous rock
• How is sedimentary rock formed?
– pressure and cementing of sediment
• What happens to rock when it melts?
– It’s magma
What are igneous rocks?
Rocks formed from magma
that’s cooled.
How are granite and basalt related?
They are both igneous rocks !
Continental crust =
mostly granite
(large crystals
formed underground).

Oceanic crust =
mostly basalt 
(small crystals
formed at the surface).
Where do sedimentary rocks come from?
They’re formed by layers
(sediments) that are the pieces of other rocks,
that are (stuck or glued) cemented
by minerals that were
left behind by water (deposited).
How are sand, sandstone, and
conglomerate connected?
Sand comes from weathering & erosion.
Wind,
water,
or ice
cause pieces of rock
to break off of larger rocks…
…sandstone and conglomerates; they’re all
sedimentary rocks that were cemented
together with the pieces of other rocks.
What are metamorphic rocks?
Rocks formed when existing rocks are
changed by heat and pressure.
Heat and Pressure
Sedimentary
Metamorphic
(limestone)
(marble)
How are shale and slate connected?
The sedimentary rock, shale is changed into
the metamorphic rock, slate by heat and
pressure.
shale
slate
What are the 3 classes of rock?
Petrologists classify rocks by how they form.
1. ________
Igneous - melted rocks (minerals)
that have cooled
2. Sedimentary
___________ - pieces of minerals, rock,
and living things that compacted together
3. Metamorphic
__________ - any rock that is changed
by heat and pressure (not fully melted)
The Rock Cycle
Concept and Challenges – What are rocks?
1. Rocks are minerals cemented together
2. There are three classes of rock:
Igneous: formed from cooling magma
Metamorphic: igneous, sedimentary, or
metamorphic rock changed by
heat/pressure
Sedimentary: formed from sand (broken
down rock) cemented together.
3. As you go deeper in the Earth, the
temperature increases or gets hotter.
4. Igneous rocks are made from magma. As
magma cools it forms igneous rocks.
5. The three main minerals that make up granite are
quartz, feldspar, and mica
6. Obsidian does not have crystals because it is lava that
cooled too quickly
7. Sediments are small parts of rock that are carried and
deposited by water, wind, or ice
8. Acid reacts with calcium, and because the sedimentary
rocks from the White Cliffs of Dover have calcium
carbonate (CaCO3), the acid would react.
9. Clastic rocks are made up of smaller rocks that
are nonliving, but nonclastic rocks are made up
of dissolved minerals or dead plants and animals.
10. Metamorphic rocks are formed by rocks that are
changed by heat and pressure.
11. You can make bread from water, flour, salt, and yeast.
First, you mix the ingredients. Then, you bake the
mixture in an oven.
12. The minerals in the rocks melt and recrystallize into
minerals that form bands.
SEDIMENT
Weathering,
Cementing
Weathering
Weathering
ggg
SEDIMENTARY
ROCK
Heat and
Pressure
Heat and
Pressure
IGNEOUS ROCK
METAMORPHIC
ROCK
Melting
Melting
MAGMA
Melting and Cooling
The Rock Cycle
Do you know…
1. What is the connection between shale
and slate?
2. What is the connection between granite
and basalt?
3. What is the connection between obsidian
and pumice?
4. What is the connection between sand,
sandstone and conglomerate?
Shale and Slate
The sedimentary rock shale is changed into the
metamorphic rock slate by heat and pressure.
Granite and Basalt
They are both igneous rocks. Granite makes up
most of the continental crust and basalt makes
up oceanic crust.
Obsidian and Pumice
They are both igneous rocks formed by the quick
cooling of lava. Obsidian is from lava that
flowed and pumice was violently ejected from a
volcano.
Sand, Sandstone and Conglomerate
The sand is sediment that has formed into the
sedimentary rocks sandstone and conglomerate.