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From the surface of the Earth the layers are
the crust, mantle, outer core, and inner core.
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The Lithosphere is the Earth’s crust and the
upper part of the mantle. This layer contains
the tectonic plates on Earth.
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The Asthenosphere is the layer of liquid
magma in the mantle below the Lithosphere.
A convection current occurs in the
asthenosphere causing the Earth’s plates to
move.
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Alfred Wegener believed that all of the
continents were once connected into a super
continent landmass called Pangaea. Wegener
believed that over time the continents drifted
apart. This theory is called Continental Drift.
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Same fossils found on different continents
Continents fitting like puzzle pieces
Migration paths of animals
Rock structures
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The sea floor spreads at mid-ocean ridges.
Mid-oceans ridges are under water mountain
chains.
Magma rises at mid-ocean ridges, solidifies,
and new crust forms.
Older Crust is pushed farther away from the
ridge closer to the continents.
Scientists discovered that the rocks farther
away from the ridge were older because they
were able to examine rock samples from
drilling on the sea floor.
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Here is an image of how the magma flows
from the mid-ocean ridges:
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This is the largest mid-ocean ridge and the
longest mountain chain in the world.
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There are three main types: Divergent ,
Convergent, and Transform.
Divergent
Convergent
Transform
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Boundary between two plates that are
moving apart
Crustal Features=mid ocean ridges at two
ocean plates and rift valleys at continental
plates
Plates move away from each other
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Boundaries between two plates that are
colliding
There are 3 types of convergent plate
boundary collisions:
Ocean-Ocean
Ocean-Continent
Continent-Continent
Continental-Oceanic
Collisions
Oceanic-Oceanic
Collisions
Continental-Continental
Collisions
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Subduction is the process of a denser crust
sinking beneath a less dense crust and back
into the mantle. This occurs at Convergent
Plate boundaries. This causes trenches and
volcanoes. Active volcanoes are only located
at plate boundaries.
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Continental plate and oceanic plate collide
The denser oceanic plate sinks (subducts)
beneath the less-dense continental crust
Trenches are found at this kind of plate
boundary.
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Oceanic plate collides with another oceanic
plate
The denser of the 2 oceanic plates sinks
(subducts)
Volcanic islands are formed at this boundary.
Trenches are found at this kind of plate
boundary as well.
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A continental plate colliding with
another continental plate
This collision causes mountains ranges
on the middle of continents.
The Himalayas Mnts. in Asia are an
example of this kind of collision.
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Boundary between two plates that slip past
each other moving in opposite directions
Theses boundaries create faults, such as
the San Andreas fault. Earthquakes form
along these faults.
San Andreas Fault
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Here is the San Andreas fault. It is an
example of a transform boundary.
◦ The Pacific plate
(west of fault) is
moving
northwest
◦ The North
American plate
(east of fault) is
moving
southeast
Pacific Plate
These maps show detailed shapes of Earth’s
surface. It represents different elevations
specifically on mountains.
 Topographic maps contain
contour lines that represent
the elevations. When the
Contour lines are close
together, it indicates a steep
slope.
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A long chain of active volcanoes and other
tectonic features such as earthquakes at the
plate boundaries surrounding the Pacific plate