Transcript Rocks WebQuest! - Crestline High School

Rocks WebQuest!
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For this WebQuest you will investigate the three types of rocks and a few
examples of each
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You will work in partners for this assignment sharing one laptop.
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You will fill out the notes sheet using this power point for the information.
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The information goes in order- you must search for the missing sections or
questions asked.
You should work on this the entire class period.
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There is an attached assignment for sorting the rock types and table generating for
classifying.
Rocks…
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Rocks are always on the move through the rock cycle! The three
types of rocks are:
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sedimentary rocks
igneous rocks
metamorphic rocks
This process is slow!
All rock (except for meteorites!) that is 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 stays the same, the rocks do not. Over millions of years, rocks
are recycled into other rocks. Moving tectonic plates help to destroy
and form many types of rocks.
Sedimentary Rocks
What Is a Sedimentary Rock?
 Have you ever been to the beach and nestled your toes in the sand?
Over thousands of years that sand might become part of a
sedimentary rock!
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Sedimentary rocks make up about three-quarters of the rocks at the
Earth’s surface. They form at the surface in environments such as
beaches, rivers, the ocean, and anywhere that sand, mud, and other
types of sediment collect. Sedimentary rocks preserve a record of
the environments that existed when they formed. By looking at
sedimentary rocks of different ages, scientists can figure out how
climate and environments have changed through Earth’s history.
Fossils of ancient living things are preserved in sedimentary rocks
too.
Cont…
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Many sedimentary rocks are made from the broken bits of other
rocks. These are called clastic sedimentary rocks. The broken bits of
rocks are called sediment. Sediment is the sand you find at the
beach, the mud in a lake bottom, the pebbles in a river, and even
the dust on furniture. The sediment may, in time, form a rock if the
little pieces become cemented together.
There are other types of sedimentary rocks whose particles do not
come from broken rock fragments. Chemical sedimentary rocks are
made of mineral crystals such as halite and gypsum formed by
chemical processes. The sediment particles of organic sedimentary
rocks are the remains of living things such as clamshells, plankton
skeletons, dinosaur bones, and plants.
Sedimentary Examples
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Limestone
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Sandstone
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Shale
Limestone
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Limestone is formed in marine environments
where bits of shell and other debris
composed of calcite are deposited on the
bottom. Chemical reactions between calcium
and bicarbonate ions may also form
carbonates, which settle to the bottom. The
calcite and other minerals may harden into
limestone. Remains of animals may also be
buried in the carbonate muds and
eventually turn into fossils. Over time uplift
and lowering of sea level may expose the
limestone layers at the Earth’s surface.
Sandstone
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Sand is carried by wind or
water until it is deposited in a
basin. Some dissolved chemicals
in rising groundwater are
deposited in spaces between the
sand grains. This chemical matrix
glues individual grains together
and forms the rock we call
sandstone.
Shale
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Clay and silt size particles are
deposited in areas of slow moving
water. Leaves and other remains of
plants and animals may get buried
in the mud. Over time, the pressure
of overlying sediments may
squeeze the water out of the mud,
and forms shale.
Igneous Rocks…
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Igneous Rocks
Igneous rocks form when molten rock cools and becomes solid.
Molten rock is called magma when it is below the Earth’s surface
and lava when it is above.
Igneous rocks are divided into two groups, based on where the rock
forms.
Igneous rocks that form below the Earth’s surface are called intrusive
igneous rocks (or plutonic). They form when magma enters an
underground chamber, cools very slowly, and forms rocks full of
large crystals.
Igneous rocks that form above the Earth’s surface are called
extrusive igneous rocks. These rocks, also called volcanic rocks, form
when lava cools quickly at or above the Earth’s surface.
Igneous Examples
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Obsidian
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Granite
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Basalt
Obsidian
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Obsidian is formed by rapid cooling of lava. It
cools so quickly it forms glass and not crystals.
Granite
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Granite is formed below the Earth’s crust from
slowly-cooling magma. Slow cooling allows larger
crystals to form.
Basalt
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Basalt is formed from lava erupting onto the Earth’s
surface. It cools relatively quickly; only small
crystals form which are not easy to see.
Metamorphic Rocks…
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Have you have heard that caterpillars metamorphose into
butterflies? Well, rocks can metamorphose too! They don't grow
wings like a butterfly. But they do change! Rocks metamorphose
when they are in a place that is very hot and pressure is high. You
can find such a place where Earth's tectonic plates are coming
together. There, the colliding plates squish rocks, and hot pools of
magma heat them deep underground.
Some rocks only change a little, while others change a lot. When a
rock is metamorphosed, its mineral crystals change. Usually, the same
chemical ingredients are used to form new crystals during
metamorphism. Sometimes new types of minerals grow that weren't
in the rock before.
Cont…
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Often, flat minerals like mica become lined up
perpendicular (at a right angle) to the direction of
pressure. When minerals within a metamorphic rock are
organized this way, it is called foliation. Some
metamorphic rocks are foliated and others are nonfoliated.
Any type of rock, can be metamorphosed. The rocks
are changed either in small areas of contact
metamorphism or large areas of regional
metamorphism.
Figure out foliation!
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Try this experiment to figure out how minerals become oriented when a rock
is under pressure.
Add mica flakes to a piece of play dough. The dough will represent a rock
undergoing metamorphism.
Knead the dough until the mica flakes are well-incorporated roll your
dough into a ball.
Break the ball of dough in half. The flakes will be oriented in all different
directions just as they would be in an unmetamorphised rock.
Take one half of the ball and flatten it with the palm of your hand. The
pressure that you are applying to the dough is like the pressure placed on
our rocky Earth by the forces of plate tectonics.
Break the flattened dough in half and look at what has happened to the
mica flakes!
Metamorphic Examples
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Gneiss
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Schist
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Slate
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Quartzite
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Marble
Gneiss
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Gneiss may be formed from any rock type that is
buried deep in the Earth’s crust and affected by the
great pressure and temperature that exists there.
Schist
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Schist is formed when rocks, such as granites, are
changed by moderate heat and temperature after
burial deep in the Earth’s crust.
Slate
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Slate is formed when fine-grained sediments, such
as shale and mudstone, are buried in the Earth’s
crust. Here the sediments are recrystallized by low
temperatures and pressures.
Quartzite
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Quartzite (also known as metaquartzite) forms from
sandstone that comes in contact with a source of
heat, such as an intrusion of Igneous rock.
Marble
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Marble forms from calcite-rich rocks, such as
limestone, that come in contact with a source of
heat, such as an intrusion of Igneous rock.
Rock Organization
Slate
Metamorphic
Igneous
Sedimentary
Limestone
Shale
Granite
Schist
Gneiss
*Organize the rocks under the
correct grouping
Obsidian
Marble
Sandstone
Basalt
Quartzite
*Come up with a few facts that are
true with all the rocks in each rock
type.
~Use your notes to help you!
Rock Classification
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How would you classify these rocks? Why?
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