Transcript Earth`s Changing Surface Review

What provides the force
that moves the tectonic
plates?
Convection Currents
Which layer of the earth
contains convection
currents?
The asthenosphere
(plastic mantle)
What 3 pieces of evidence
did Wegener use to support
his theory of continental drift?
 Fossils
 Landforms (continents match up)
 Climate (glacial scratches on
bedrock)
Why did scientists
reject Wegener’s
theory of Continental
Drift?
He could not identify
the force that moves
the tectonic plates
What three pieces of
evidence did Hess use
to support his theory of
Sea Floor Spreading?
 Magnetic stripes on the
sea floor
 Molten material
 Evidence from drilling
samples
If new sea floor is
constantly being created
at mid-ocean ridges why
isn’t the Earth getting
bigger?
Other areas of the ocean
floor are being subducted
into the mantle
Why was the discovery of
sea floor spreading so
important?
It proved that new
seafloor features are
constantly being
added
What crustal formations
are created when an
oceanic and continental
plate collide?
Trenches and volcanic
mountains
What crustal formations
are created when an
oceanic and oceanic plate
collide?
Trenches and volcanic
island arcs
What crustal formations
are created when a
continental and
continental plate collide?
Folded Mountains
What happens along
transform boundaries?
Faults (earthquakes)
What crustal formations
occur at divergent
boundaries?
Mid-ocean ridges and rift
valleys
Where do hot spots occur?
Hot spots occur at weak
spots in the Earth’s crust
What are the 4 main
layers of the Earth’s
interior?
Crust, Mantle, Outer core, Inner
Core
How do convection
currents in the mantle
move the crust above?
The heating and cooling of a fluid,
changes in the fluid’s density, and
the force of gravity combine to set
convection currents in motion. As
the convection currents move, they
move the crust above them.
What is the theory of
Plate Tectonics?
The theory states that pieces
of Earth’s lithosphere are in
constant, slow motion, driven
by convection currents in the
mantle
What is sea floor spreading?
The process by which
molten material adds new
oceanic crust to the ocean
floor
What do topographic
maps show?
They show the surface
features of an area.
What are contour lines?
Imaginary lines that join
equal points of elevation
on a topographic map
How are steeper areas
represented on topographic
maps?
Contour lines get closer
together as land gets
steeper
How are gradual slopes
represented on
topographic maps?
Contour lines get farther
apart as land gets flatter
Why are earthquakes and
volcanoes often found
along plate boundaries?
The interaction of tectonic
plates cause earthquakes
and volcanoes.