Transcript Plate Tectonics - cloudfront.net

What are Earth’s layers?
 BrainPop- Earth’s Structure
 Core- central part of the Earth
 Inner Core- made of solid metals
 Outer Core- made of liquid metals
 Mantel- thick layers of solid and
molten rock that lies around the core
 Upper Mantel- the top of the upper mantel
(solid rock) joins with the
crust to form the lithosphere
-the rest of the upper mantel
(melted rock) is the
asthenosphere
 Lower Mantel- solid rock
What are Earth’s layers?
 Crust- the thin layer of solid rock that makes up the
outermost the Earth
 All of the Earth’s liquid and solid waterincluding oceans, lakes, rivers, glaciers, and
water located underground- makes up the
hydrosphere.
 The Earth’s crust makes up the surface of
Earth. What does the surface include?
 the continents and oceans
 Geological features are also
found on the surface.
 These are physical structures
such as rivers, lakes, and desserts.
the
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Review
 What are the different layers of the Earth?
 Earth’s Layers- Labeling Game
 From which layer of Earth do people get most of their
resources?
 the crust
 Which layer of the Earth is made up of all of the Earth’s
solid and liquid water?
 Hydrosphere
 What is the lithosphere and what does the lithosphere
rest on?
 It is the crust and the top part of the upper mantel. It rests
partly on melted rock that makes up the upper mantel
called the asthenosphere.
Are the continents moving?
 About 100 years ago a German geologist, Alfred
Wegener noticed that the continents looked like
pieces of a jigsaw puzzle.
His theory that at one time all of the continents were
connected and then moved apart by some force
became known as the Theory of Continental Drift.
Evidence Mountains on the east coast of South America and the
west coast of Africa had the same types of rocks and
the rocks were the same age
 Plant and animal fossils were also found like this. The
animals would not have been able to swim the span of
the ocean. What would you have concluded?
 Scientists have concluded that all of the continents
were once a part of a a supercontinent called
Pangaea.
 More evidence supported this theory in the 1950s
when scientists were mapping the floor of the Atlantic
Ocean and found that there was an underwater
mountain chain. On both sides of the mountain chain,
the ocean floor was moving.
 Continental Drift
Review
 Continental Drift2- (Click on the animated gifs)
 What caused the scientists to conclude that Earth’s
continents were once joined?
 evidence from fossils and rocks
 How might large pieces of land be able to move?
 They would need to be on top of something that could
move.
 What would happen to the plants and animals on that
large landmass?
 Some would be on one part and the rest would be on
the other.
What causes the ocean floor to move?
 BrainPop- Plate Tectonics
 Explain the theory that scientists call plate tectonics.
 It is the theory that explains how forces deep within Earth
can cause ocean floors to spread and continents to
move.
 This theory describes the lithosphere being made of huge
plates of solid rock. The continents rest on these plates.
 The almost-melted rock of the asthenosphere acts as a
slippery surface on which the plates can move.
 In the middle of the ocean when the plates move apart
what is pushed up from the mantle towards the surface?
 Magma- It is hot, melted rock.
 The magma causes tension, or a stretch or push on the
plates. What do you think the push does to the ocean
floor?
 This means that the ocean floor moves apart and
separates the plates that the continents rest on. This
process is called spreading.
 What happens to the hot magma when it reaches the
surface?
 It cools and forms the mid-ocean ridge. These ridges are
underwater mountain ranges.
 As the ocean floor grows wider, the continents grow
farther apart.
 At the Mid-Atlantic Ridge Ocean, new seafloor crust is
formed at the rate of about 1.5 inches per year. (Turn to
pg 201 to see the image of the ocean floor spreading.)
Review
 Where is the newest ocean floor?
 The part of the crust that makes up the mid-ocean
ridges.
Review
 What do you notice about the plates?
 Some of the plates are pushing against each other. Some
of the plates are moving away from each other. Many of
the locations where the plates push against each other
are sites of mountain ranges.
What forces change Earth’s crust?
 A transform boundary is when plates slide past each
other.
 A force called shearing causes rocks to break as
plates rub past each other. When the rocks pile up,
they form narrow ridges and valleys.
 What do you think occurs when the plates rub against
each other?
 Earthquakes
 Most transform boundaries are located on the ocean
floor. The most noticeable one on land is the San
Andreas Fault between the North American plate and
the Pacific Plate.
 Convergent boundaries are locations where plates
collide.
 Divergent boundaries are locations where plates
move apart.
 Boundaries Animated
 A fault is a break or crack in the rock of the
lithosphere along which movements take place.
Faults are located along the boundaries between the
tectonic plates.
Three kinds of faults
 Three Faults- Animated
 San Andreas Fault
What are the different types of mountains?
 Folded Mountains are mostly made of rock layers that
are folded together by compression.
(Great Smoky Mountains and the Himalayas in Asia)
 Fault-Block Mountains are made of huge tilted blocks of
rock separated from the surrounding rock by faults.
(Sierra Nevada and the Teton Range)
Folded Mountains
Fault-Block Mountains
Review
 Review Site- Click on Each Topic from Intro. to
Slip, Slide, and Collide
 National Geographic- Plate Tectonics
 Ology- Plates on the move
 Plate Boundary map
 Earth Floor- Pate Tectonics