Download Igneous and Sedimentary Rocks

ROCKS
Explain how extrusive and intrusive igneous
rocks are different.
Describe how different types of sedimentary
rocks form.
Describe the conditions needed for
metamorphic rocks to form.
ROCKS: Igneous
• The deeper you go into
the interior of Earth, the
higher the temperatures
is and the greater the
pressure.
• Igneous Rock;
forms when
melted rock from
inside Earth
cools.
ROCKS: Igneous
• When melted
rock material
cools on Earth’s
surface, it makes
extrusive
igneous
rock.
REVIEW QUESTION
• What do you call melted rock
material on Earth’s surface?
• Lava
ROCKS: Igneous
• Extrusive
igneous rocks
can form in two
ways.
1. Volcanoes
erupt and
shoot out lava
and ash.
CONT
ROCKS: Igneous
2. Large
cracks in
Earth’s
crust, called
fissures,
open up
oozing lava.
ROCKS: Igneous
• Intrusive
igneous rock:
When the rock
melt occurs and
cools beneath
Earth’s surface.
CONT
REVIEW QUESTION
• What do you call melted rock
material below the Earth’s
surface?
• Magma
ROCKS: Igneous
• Intrusive igneous
rocks forms from
magma. This hot
mass of rock material
sits under the surface
cooling over millions
of years until it is
solid.
• The cooling is so
slow that the
minerals form large
crystals.
CONT
ROCKS: Igneous
• Rocks that cool
quickly usually
form small crystals
that are difficult to
see.
• Rocks that cool
slowly usually form
larger visible
crystals.
REVIEW QUESTION
Rocks that cool quickly usually form
small crystals that are difficult to see.
Question: What type of igneous rocks
are these?
Extrusive igneous rocks.
REVIEW QUESTION
• Rocks that cool slowly usually form
larger visible crystals.
• Question what type of rocks are
these?
• Intrusive igneous rocks
ROCKS
• How do rocks
get their color?
–Chemicals
ROCKS: Igneous
• Chemical composition of
rocks:
–Light colored rocks are called
granitic rocks.
–Dark colored rocks are called
basaltic rocks.
ROCKS: Igneous
• Granitic rocks
are often
intrusive.
• Basaltic rocks
are often
extrusive.
ROCKS: Sedimentary
• How do you think sedimentary rocks
formed?
• Layers of sediment are deposited
over many years.
CONT
ROCKS: Sedimentary
• Sedimentary rocks are formed from pieces
of broken rock, shells, mineral grains and
other materials.
• This sediment collects in layers to form
rocks; sedimentary rocks.
ROCKS: Sedimentary
• How is sediment carried to a
location?
1.
2.
3.
4.
5.
Rivers
Ocean waves
Mudslides
Glaciers
Wind
ROCKS: Sedimentary
• After the sediment is
deposited it takes
thousands to millions
of years to become
sedimentary rock.
ROCKS: Sedimentary
• Three categories of
sedimentary rock.
• Detrital Rocks:
Made up of grains of
minerals or other
rocks deposited in
layers. Minerals
dissolved in water
cement these
particles together.
Gravity also compacts
the layers into rock.
CONT
ROCKS: Sedimentary
• Detrital
Rocks:
• Sandstone is
an example of
a detrital rock.
ROCKS: Sedimentary
• Chemical Rocks:
• Form when
seawater, geysers,
or hot springs (all
loaded with
minerals)
evaporate.
CONT
ROCKS: Sedimentary
• Organic Rocks:
• Living matter dies, piles up, and is
compressed into rock.
• Question:
– Can you give examples?
1. Chalk
2. Coal
ROCKS: Sedimentary
• Limestone
• Coal
• Chalk
• Video: Sedimentary
• 3:36
ROCKS: Sedimentary
• Fossils:
– A fossil is the remains or trace of a once-living
plant or animal.
– Chalk and limestone are made from fossils of
millions of tiny organisms.
ROCKS: Metamorphic
• Rocks get recycled just as humans recycle
aluminum cans.
• This process usually occurs way
below the Earth’s surface where
temperatures and pressures are high.
• New rocks form when existing
rocks are heated or squeezed but
not melted.
CONT
Rock Cycle
• Rocks are recycled constantly from one
kind of rock to another. Video Rock Cycle
ROCKS: Metamorphic
• Two Types of Metamorphic Rock:
1.) foliated – have visible layers or
elongated grains of minerals
ex: slate, gneiss, phylite, schist
2.) nonfoliated – do not have distinct
layers or bands (grains, if visible, do not
line up in any particular direction)
ex: quartzite, marble, soapstone