Transcript 8-3.4 Three Types of Rocks

SC Standard 8-3.4
Explain how igneous, sedimentary and
metamorphic rocks are interrelated in the
rock cycle.
Rocks
• Rocks are naturally occurring
combinations of minerals.
• Most consist of two or more different
minerals.
• Rocks are classified according to how
they were formed.
Physical Properties of Rocks
1. Color (may have a distinctive color for
identification)
2. Streak (is the color of the mineral in powered
form- shows the true color of the mineral)
3. Hardness (is a measure of the mineral’s
resistance to scratching)
4. Luster (property of minerals that indicates how
much the surface of a mineral reflects light or
if it is SHINY.)
3 TYPES OF ROCKS
• IGNEOUS
• SEDIMENTARY
• METAMORPHIC
Igneous Rocks (Volcanoes)
• Igneous – means “fire formed.”
• IGNEOUS ROCKS: form from lava or
magma. (MOLTEN ROCK)
– Think of candle wax cooling
– Igneous Rocks forms around
VOLCANOES…
2 types of Igneous Rocks
• When lava is cooled it forms a rock.
• When magma cools within the Earth, it
also forms rocks.
Igneous Rocks (Volcanoes)
• Intrusive rock – Igneous rock that formed when
magma hardened beneath or inside a
volcano. (interior – inside)
• Rocks cool slowly
– Mineral crystals that form are large
– Example: Granite
Intrusive: Large crystals – Cools
Slowly
Igneous Rocks (Volcanoes)
• Extrusive rock – Igneous rock formed from lava
that erupted from a volcano. (exterior – exit)
• Rocks cool quickly
– Mineral crystals are small or no crystals are formed
– Examples: Basalt,
Obsidian
• Extrusive: Small crystals – Cools Quickly
WHAT TYPE OF IGNEOUS ROCK FORMS
IGENOUS ROCKS PROCESSES
• Igneous Rocks goes mainly through
processes:
• 1. Crystallization
• 2. Melting
• 3. Cooling
• 4. Deposition
Review
1. Where do igneous rocks form?
2. The only way igneous rocks can form is from
the cooling of what?
3. Can a pre-existing rock ever become an
Igneous rock?
4. What are the two types of igneous rocks?
Explain the difference between them.
5. What are the 2 processes igneous rocks go
through?
6. Explain how large and small crystals form in
igneous rocks.
SC Standard 8-3.4
Explain how igneous, sedimentary and
metamorphic rocks are interrelated in the
rock cycle.
Sedimentary Rocks
• Forms near bodies of water or
where bodies of water use to be
• Sedimentary rocks are made up
of sediments.
What are Sediments?
• Sediment are small, solid pieces of
rock, mineral grains, or shell
fragments
• Sediments are formed through the
processes of weathering and
erosion of rocks exposed at Earth’s
surface.
• .These rocks are always forming all
around you.
Two Processes that make
Sedimentary Rocks
• 1. Compaction - process that presses
sediments together.
– At first, the sediment fits together loosely.
Over long periods of time the layers build up.
– The layers are heavy and press down on
each other.
• Cementation – process in which
dissolved minerals crystallize and glue
sediment together.
Sedimentary Rocks
• Sedimentary rocks usually have
fossils within them.
• Sedimentary rocks are also
known for having layers.
Review Questions
• Where do sedimentary rocks form?
• What are the two processes that
sedimentary rocks go through?
• How do sedimentary rocks form?
• What are sediments?
• How do sediments form?
SC Standard 8-3.4
Explain how igneous, sedimentary and
metamorphic rocks are interrelated in the
rock cycle.
Metamorphic Rocks
• Metamorphic rocks form underneath the
Earth’s Surface.
• Forms when rocks are changed into
different kinds of rocks by great heat
and/or pressure
• Metamorphic rocks are heated,
squeezed, folded, or chemically
changed by contact with hot fluids.
Metamorphic Rocks
Processes
• Metamorphic goes through 2
processes:
• 1. Heat
• 2. Pressure
Metamorphic Rocks
Classification
Classified by the arrangement of the grains
that make up the rocks.
• Foliated Rocks – Have obvious layers.
• Non-Foliated Rocks – Have no visible
layers.
Foliated or nonfoliated?
metamorphism of shale
SHALE is the most common sedimentary rock.
Through the agents of metamorphism it changes to rocks that
are stable at higher temperatures and pressures.
These changes take place in the solid state.
GRANITE
Slate
Shale
Increasing Temperature and Pressure
Phyllite
Schist
Gneiss
Granite (igneous) = GNEISS (metamorphic)
Limestone (sedimentary) = MARBLE (metamorphic)
Shale (sedimentary) = SLATE (metamorphic)
RC (Review Check)
• Types of Rocks
RC (Types of Rocks Questions)
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1. Forms underneath the Earth’s surface
2. Forms around volcanoes
3. Forms near bodies of water or where bodies of water use to be
4. Have fossils within them
5. Goes through the process of cooling, melting, and crystallization
6. Goes through the process of heat and pressure
7. Goes through the process of compaction and cementation
8. Consist of Intrusive and extrusive rocks
9. Can change into other rocks, can be foliated and go through
chemical changes
• 10. Can go through the process weathering and erosion
THE ROCK CYCLE
• The rock cycle is an ongoing process.
The sample diagram illustrates the series
of natural processes that can change
rocks from one kind to another: