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ROCKS
Rock Vocabulary
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Sediment
Rock cycle
Weathering
Stratification
Igneous rock
Sedimentary rock
Metamorphic rock
Cementation
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Porphyritic texture
Intrusive igneous rock
Extrusive igneous rock
Conglomerate
Fossil
Ripple mark (look in
chapter in sedimentary
rock section)
What is a rock?
What is a rock?
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Maybe made of entirely one mineral or several
minerals.
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May contain organic matter (composed of living
material, usually carbon based)
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Rocks containing different combinations of the
same minerals are different.
Forms of the same mineral
Example: Carbon may be found as a
lump of coal or as a diamond. Quite
different!
COAL
DIAMOND
Types of Rocks
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What are the three classes of rocks?
Types of Rocks
What are the three classes of rocks?
1. Igneous Rocks
2. Sedimentary Rocks
3. Metamorphic Rocks
Igneous Rocks
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Name comes from the Latin word “ignis” meaning from fire.
Formed when super hot magma or lava cools.
There are seven different classes based on chemical
composition of the igneous rock.
Types of Igneous Rocks
As magma moves quickly
from the super hot
conditions of the Earth
to the much cooler
surface and becomes
lava, it solidifies quickly
 This rock is called
extrusive igneous rock
 Fine-grained rocks.
Ex. basalt and rhyolite
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david-amador.com
geology.com
Types of Igneous Rocks
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Intrusive igneous rock forms
when pockets of magma are
trapped below the earth’s
surface and cool slowly
The magma cools much
slower and therefore forms
larger crystals.
Larger crystals give these
rocks a rough texture
Ex. granite
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Mount Rushmore is carved
from granite in the Black
Hills of South Dakota.
Mount Rushmore is carved from granite in the Black
Hills of South Dakota.
Igneous Rock
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The best known igneous
rock is granite.
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It is composed almost
entirely of feldspar and
quartz
Sedimentary Rocks
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All sedimentary rocks are made of materials called
sediments deposited by a particular force or process.
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Those sediments become cemented or compacted
together, over time forming a solid rock
Types of Sediments
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Tiny grains of sand
Broken pieces of rock along the bottom of a
stream
Fragments of seashells
Layers of mud
Organic matter (plant and animal remains)
Sediments and Sedimentary Rocks
Gravity, water, or wind carries them to a destination.
 Sediments deposit in layers. ( strata=layers of sediment)
 Loosely deposited sediment becomes a rock through
compaction or cementation.
Compaction: sediments squeezed together by gravity/pressure.
Cementation: sediments glued together by minerals deposited by
water.
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Sedimentary Rock
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The most common
sedimentary rock is
limestone.
Develops from living
remains (shells, mollusks)
Coal is another example
of rock derived from
organic remains
Sedimentary Rock
Ripple marks formed in the
sand by wind
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Often preserve some characteristics from which they
were formed.
Ripple marks formed in the sand will appear in the rock
formed from the sand deposits.
Sedimentary Rocks
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The source of most fossil
remains.
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The age of a rock can be
determined by studying
the fossils within it.
Fossilized Leaves
Sedimentary Rocks
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The color of the
sedimentary rock also
gives us a clue about its
chemical composition
The red and pink bands
in the Grand Canyon
exhibit the iron found in
the sediment.
Sedimentary Rocks: Location
 Sedimentary
rocks cover almost all of
the ocean floor and about threefourths of Earth's surface land area.
Metamorphic Rock
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Heat, pressure, and hot fluids cause rocks to change
into other rocks.
Where would this most likely occur?
Metamorphic Rock
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Heat, pressure, and hot fluids cause rocks to change
into other rocks.
Where would this most likely occur? within the Earth
at subduction zones
when magma cools
Metamorphic Rock
Formed from compression of
Tectonic plates
The geologic processes that created the North Cascades
changed the original rock into metamorphic rock.
Types of Metamorphic Rock
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Slate is a common form
that is easily split into
slabs
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Gneiss (pronounced
“nice”) contains light and
dark bands
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Granite is also a
common type
The Rock Cycle
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Almost all of the rock that we have on Earth
today is made of the same stuff as the rocks that
dinosaurs and other ancient life forms walked,
crawled, or swam over. While the stuff that
rocks are made from has stayed the same, the
rocks themselves, have not. Over time rocks
are recycled into other rocks.
The Rock Cycle
The Rock Cycle