Download ROCKS

ROCKS
• A Rock is a naturally
formed solid that is usually
made up of one or more
types of minerals
ROCKS vs. Minerals
Rocks
1.Proportions of minerals
vary
2. Minerals can be
jumbled together
3.None to 1 or more
minerals can be present
Minerals
1. Is the same elements
in the same
proportions
2. There is an orderly
crystal structure
Examples of Rocks
Rocks with no minerals
OBSIDIAN – glass like and does
not have a crystal structure
1 or more minerals
LIMESTONE- can be made
entirely of calcite
COAL- is made of dead plants
GABBRO- made of several
types of minerals
Our world is built of rocks
Rock is so common and has
many purposes
They last a long time
1. Building houses and
skyscrapers
2. Sources of metal like iron
aluminum and copper
3. Carvings of statues and art
4. Pavement on roads and
highways
Ancient structures,
monuments and sculptures
were made from rock
• Great wall of china
• Pyramids in Egypt
• Mount Rushmore
Rocks change as they move through
the rock cycle
The Rock cycle is a set of natural processes that
form, change, and break down, and reform rock.
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Rocks are classified by how they form
There is no particular order to the rock cycle
There is no beginning and no ending
These changes take thousands to million of years
TYPES OF ROCKS
1. IGNEOUS- Forms when molten rock cools and
becomes a solid (lava and magma)
2. SEDIMENTARY- Forms when pieces of older rocks,
plants, and other loose materials are pressed
together at the earths surface (weathering and
erosion)
3. METAMORPHIC- Forms when older rocks buried
deep in the crust change into new types of rock (heat
and pressure)
IGNEOUS ROCKS
Rocks that form when molten (melted)
rock cools and becomes a solid
Temperatures deep within the Earth are so hot (1400 °F2300 °F) that rock will melt
MAGMA
Molten Rock that is
below the surface of
the Earth
LAVA
When magma reaches
the surface of the Earth
it is called Lava
1. Composition
Igneous rocks are classified by how much silica
content they have
Igneous rocks are mostly made of silicate
minerals (silica and oxygen)
Color will give you a good estimate of the
amount of Silica
HIGH LEVELS OF SILICA
LOW LEVELS OF SILICA
Color= Light
Color= Dark
GRANITE
BASALT
RHYOLITE
GABBRO
2. Origins of Igneous rocks
Magma and Lava form different types of igneous rocks
INTRUSIVE IGNEOUS ROCK
EXTRUSIVE IGNEOUS ROCK
One that forms when
magma cools within the
Earth (INside)
One that forms when
lava cools on Earth
surface (EXterior)
Granite
Rhyolite
Pumice
same composition
Same composition
Gabbro
Basalt
3.TEXTURE- the size of its mineral crystals
-Depends on how fast the magma or lava cool
Intrusive- Stay below
the Earth
Extrusive- At the
surface
LARGE CRYSTALS FORM FROM
MAGMA
1. The interior is very hot
2. High temperature allows
for slow cooling
3. Slow cooling allows time
for LARGE CRYSTALS
SMALL CRYSTALS FORM FROM
LAVA
1. The surface is cooler
than inside Earth
2. Low temperatures cause
lava to cool fast
3. There is no time for large
crystals to form
ROCK FORMATIONS
Igneous rocks make long-lasting landforms
INTRUSIVE ROCK FORMATIONS
EXTRUSIVE ROCK FORMATIONS
• Magma can slowly cool
inside a volcano.
• Over time, wind and water
can wear away surrounding
rock to expose the intrusive
rock.
• These landforms are harder
and longer lasting than
other types of rocks
• Lava erupts in different
ways
• 1. low silica lava, like basalt,
flows easy in thin layers
(Hawaii, Columbia Plateau)
• 2. High silica lava builds
steep cone shaped
volcanoes and erupt
explosively (Mt. St. Helens)
Devils rock and Ship rock
Are examples of Intrusive Rock
Formations
HAWAIIAN ISLANDS
Low Silica lava flow form extrusive rock formation
in thin layers
MT. ST. HELENS
High Silica Lava forms Extrusive land formation
with violent erupts
3.3 Sedimentary Rocks
• Some rocks form from rock particles
• Most sedimentary rocks form from loose
material that gets pressed together.
• Sediments are materials that settle out of
water or air.
• Sediments can be loose pieces of rocks and
minerals or even plant and animal remains.
Sedimentary rocks develop layers
Types of Sedimentary Rock
• Made of other rock particles, classified by
particles size.
– Big particles (pebbles and bigger) conglomerate,
puddingstone
– Smaller particles – sandstone, shale, mudstone.
• Made of plants or shells
– Plants (formed in swamps) coal
– Shells (dissolved water or not) limestone, chalk
3.4 Metamorphic Rock
• Heat and Pressure can change a rock
• Because pressure and temperature increase
with depth, rocks change more when they are
buried deeper in the crust.
• The deeper the rock, the more heat and
pressure it is exposed to, the more it changes.
Foliated vs. Nonfoliated Rocks
• Foliation is an arrangement of minerals in flat
or wavy parallel bands.
• Foliation occurs when rocks are under
pressure.
– Rock must contain more than one type of mineral.
• Nonfoliated rocks occur when heat and
pressure are applied to rocks that contain only
one kind of mineral
– Limestone becomes Marble
Foliated vs. Nonfoliated Rocks