Transcript Earth!!! - CanScience

Earth!!!
How is it
structured???
Draw what you believe the
structure of the Earth is.
Be sure to label all of your
layers!!! 
Earth’s Structure
• The crust
• The mantle
• The outer core
• The inner core
Earth’s Structure
• The crust
- the “shell” of the Earth
- the thinnest layer
- the coolest layer
- made up of mostly oxygen and silicon
• The mantle
- takes up 80% of the volume
- warmer than the crust
• The outer core
- very hot
- made of liquid metal of iron and nickel
• The inner core
- hottest layer
- made of solid metal
Density of Earth’s Layers
Which layer is most dense???
the core
or
the mantle
You do the math… D = m/v
Core: mass = 33% = .33
volume = 16% = .16
Mantle: mass = 67% = .67
volume = 84% = .84
Results…
The core: D = 2.1
The mantle: D= .80
And the winner is….
CORE!!!
The Tectonic Plates
Fit together like a puzzle that covers
the Earth…
The Tectonic Plates
Are the plates moving or sitting still???
What is the theory that the plates are
moving?
Continental Drift
The Evidence that supports this
theory…
- the continents look like they “fit” together like puzzle
pieces. (Pangaea the “Super Continent”)
- Fossils of the same plants and animals have been
found on continents that are oceans apart.
- The same types of rocks and minerals have been
found on continents that are oceans apart.
- Magnetic orientation of rocks on the ocean floor
…more on this later!
Pangaea
• Alfred Wegener was
a German
climatologist and
arctic explorer who
suggested the
concept of
continental drift.
• Continental drift is
the idea that the
continents move
around on Earth’s
surface.
Movement of continents
• Wegener thought that
the continents we
know today had once
been part of an earlier
supercontinent.
• He called this great
landmass Pangaea.
Movement of continents
• The surface of Earth is
broken into many
pieces like a giant
jigsaw puzzle.
• Plate tectonics
describes how these
pieces move on
Earth’s surface.
Evidence for continental drift
• Wegener’s belief was
a scientific hypothesis
based on
observations.
• Continental drift was
accepted by all
scientists because
there was no evidence
at the time to explain
how continents could
Evidence for continental drift
• Coal beds stretch
•
across the eastern U.S.
and continue across
southern Europe.
• Matching plant fossils •
are found in South
America, Africa, India,
Australia, and
Antarctica.
• Matching reptile fossils •
are found in South
America and Africa.
• Matching early mammal
fossils are found in
South America and
Africa.
Fossils in South America
and Africa are found in
rocks of identical age and
type.
Matching rock types and
mountain belts occur in
North America and the
British Isles, and Africa
and South America.
Evidence of glaciers is
present in regions with
warm, dry climates.
Continents that are close
to the equator today were
once closer to the South
Pole in the distant past.
Let’s Review!!!
What are the 4 layers of the Earth?
A: crust, mantle, inner and outer core
What layer of the Earth is most dense?
A: the core
What layer of the Earth is hottest?
A: the inner core
What theory supports the movement of the plates?
A: continental drift
Name a piece of evidence supporting continental
drift.
Why are the plates
moving?
Okay… we know that the plates are
moving, but what is making them move?
Convection Currents
How does hot air or liquid move?
What is something in the Earth’s layers that
depends on this movement?
What about cold air or liquid?
Convection Currents
Magma rises
when
heated
Hot magma cools
and
sinks
Cooler
magma
is
heated
Density and Earth’s materials
• The oceanic crust is
made mostly of
basalt.
• The continental
crust is made mostly
of andesite and
granite.
Density and Earth’s materials
• Heating the lower
mantle causes the
material to expand.
• Since less dense
materials float on
more dense materials,
a convection current
develops.
Floating continents
•
•
Earth’s crust is made of different types of
rock that are less dense than the mantle.
It’s hard to imagine rocks floating on other
rocks, but this is what happens inside
Earth!
Floating continents
•
Earth’s crust floats on the mantle just like the
boat.
•
A mountain on land is just like the stack of
blocks.
•
Crust with a mountain sticks down into the
mantle.
Floating continents
• The average
thickness of
continental crust is
30 kilometers.
• A combination of a
mountain and its
bulge underneath
may make the crust
as thick as 70
Layers of Earth
• Compare and contrast the details of the
different layers of the Earth.
What causes convection in the
earth’s mantle?
•
•
•
•
A) earth’s rotation
B) buoyancy
C) pressure deep within the earth
D) Breakdown on radioactive isotopes
• Radioactive isotopes produce heat…and
heat causes convection currents
Plate Boundaries
What is a plate boundary?
A: Where two plates touch each other. (Like two puzzle
pieces)
There are three types of plate boundaries.
The type of boundary depends on how the plates are
moving with each other…
Plate Boundaries:
1.Divergent
These plates are moving away from each
other.
Plate Boundaries:
2. Transform Fault
These plates are sliding along side each
other.
Plate Boundaries:
3. Convergent
These plates are moving into each other.
Convergent Boundaries:
•
There are a couple of different things that can
happen at this boundary because there are 2
different types of crust on Earth.
•
There is continental crust (crust that is mostly
above water: land)
And
•
There is oceanic crust...that is under the water.
•
The continental crust is less dense than the
oceanic crust… so what happens when the two
different crusts collide at a convergent
boundary???
Convergent Boundaries
A: Since the Oceanic crust is more dense it
dives beneath the Continental crust
= SUBDUCTION ZONE (picture A)
Convergent Boundaries
• Continental–Continental collision (picture C)
The crust buckles UP and forms large
mountains.
Geological Formations
At each boundary different geological
formations (mountains, volcanoes,
trenches, earthquakes, faults, etc.)
occur because of the movement of the
plates.
Lets look at what forms at each
boundary…
Geological Formations – Divergent
Seafloor Spreading
Mid-oceanic ridges and Volcanoes
Geological Formations –
Convergent (NO subduction)
Large Mountains
Geological Formations –
Convergent (WITH subduction)
Volcanoes, Mountains, and Oceanic Trenches, island arcs
Geological Formations –
Transform Fault
Faults and Earthquakes
Question???
• We now know that new rock is created at
divergent boundaries b/c of seafloor
spreading.
• Explain why the Earth’s mass is NOT
increasing as a result.
• Use the Law of Conservation of Matter in
your answer.
Let’s Find Some of These
On a MAP…
• Just by looking at a
3-D map you can determine
what type of plate boundary
there is b/c of the
formations that occur!!!
Let’s Review…
• Convergent Subduction Zone occurs at
the Peru-Chile Trench and Andes Mts.
between the NAZCA and SOUTH
AMERICAN PLATES.
• Convergent (NO subd.) occurs at the
Himalaya Mts. between the INDIAN
and EURASIAN PLATES.
• Transform Fault occurs at the San
Andreas Fault (in California!!!) between
the NORTH AMERICAN and PACIFIC
PLATES.
• Divergent (Mid-Oceanic Ridge) occurs
at the Mid-Atlantic Ridge between the
NORTH AMERICAN and AFRICAN
PLATES.
• The RING OF FIRE occurs around the edge of the
entire PACIFIC PLATE. (Earthquakes and
Volcanoes)
Density and Earth’s materials
• Today aluminum and silicon, which have
low densities, are common in Earth’s
crust.
• Earth’s inner and outer cores are
composed mostly of very dense iron.
Final Exam Focus
• Be able to locate and label the layers of the
Earth.
• Know where the major plates are on a map.
• Be able to describe the geological processes
that are occurring at given boundaries on a
map.
• Be able to locate on a map: a convergent
boundary w/ subduction, the ring of fire, a
divergent boundary, and a transform fault
boundary.
• Know the supporting evidence of plate
tectonics.
• Know the best possible explanation for
the movement of the plates.
• Know what Pangaea is.
There are 18 questions on your final
exam dealing with PLATE
TECTONICS! BE READY!