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Plate Tectonics
Chapter 4
Lesson 1
Pages 166-177
What are Earth’s layers?
O Scientists have
gathered evidence
from earthquakes
and volcanoes to
form a model of
Earth’s interior.
O Earth is made of
layers
O Core- Earth’s central
part
O The inner core is
made of solid
metals
O The outer core is
made of liquid
metals
What are Earth’s layers
O MANTLE- the thick
layer of solid and
molten rock that
surrounds the core
O Top of upper mantle
is solid rock
O Lower mantle is
solid rock
O CRUST- a thin layer
of solid rock that
makes up the
outermost layer of
Earth
O Imagine it as the
skin of an apple.
What are Earth’s layers?
Lithosphere
O The crust and the top
of the upper mantle
make up the
lithosphere
O The lithosphere is the
solid, rocky crust
covering the entire
planet which includes
landforms
Hydrosphere
O All Earth’s liquids and solid
water-including oceans, lakes,
and rivers, glaciers, and the
water underground-makes up
the hydrosphere
O The hydrosphere covers
about 70 percent of
Earth’s surface
O Most of Earth is salt water,
a small fraction of Earth’s
water is fresh and most
fresh water is frozen (ice
around North and South
Pole)
Landforms
O Physical feature on
Earth’s surface. You
will find these
located on the crust
of Earth
O Mountains, hills,
rivers, lakes, deserts
are all examples of
landforms
Are the continents moving?
O Alfred Wegener, a geologist,
O Evidence: Wegener found
noticed that the continents
appeared to fit together like
pieces of a jigsaw puzzle
O A geologist is a scientist who
examines rocks to find out
more about Earth’s history
and structure
O He believed that millions of
years ago, the continents formed
1 huge landmass known as
Pangea.
O The Theory of Continental Drift is
responsible for Pangea breaking
apart into the 7 continents
evidence that the
mountains of the East Coast
of South America had the
same type of rocks as the
mountains of the West
coast of Africa
O A Mesoraurus has been
found in very old rocks in
South America and Africa. It
could not have been
possible that this animal
swam across the ocean to
get from one continent to
another.
What causes the continents to
move?
O The ocean floor between
South America and Africa is
spreading at a rate of about
4cm every year and has
been for the past 130
million years
O Scientists developd a theory
called Plate Tectonics
Earth can cause seafloors
to spread and continents to
move
O This theory describes the
lithosphere as being made
of huge plates of solid rock
O
O Earth’s continent moves with
these plates (see picture on page
172)
O The lithosphere is described as
being made of huge plates and
solid rock and the asthenosphere
acts as a conveyor belt that
moves the plates
Magma is being pushed from the
mantle toward the surface (pg.
173) and causes the land to
move.
O At the same time, plates are also
colliding and one plate will sink
under another
O
How do mountains form?
O When plates collide, the
force that results is called
compression.
O This is the squeezing or
pushing together of the
crust
O When a continental
plate is compressed, the
ground is forced upward
and creates folded
mountains
How do mountains form?
O As the seafloor spreads, a
mid-ocean ridge forms
O When this occurs on land,
tension pulls the crust apart
and form faults
O Faults are deep cracks in
Earth’s crust where rocks
move in opposite directions
O Fault block mountains
are formed as a result of
this tension