Download How does the Earth`s crust move?

How Does The Earth’s
Crust Move?
How does the Earth’s crust move?
A Discovery. . .
• Geographers and cartographers in the
1500s noticed the continents’ edges
seemed to fit together like puzzle pieces.
• Scientists in the 1900s mapped the edges
of the continents (under the oceans) and
found that the continents fit together
even better.
How does the Earth’s crust move?
What do you think?
How does the Earth’s crust move?
A hypothesis is formed. . .
• Scientists thought maybe the
continents were once connected to each
other, and have moved apart.
How does the Earth’s crust move?
Evidence supports the hypothesis. . .
• Fossil deposits
• Ancient mountain ranges
• Coal deposits
• Deposits from glaciers
• And more. . .
How does the Earth’s crust move?
A theory is born. . .
Plate Tectonics
• Explains how the continents move
• Earth’s crust is divided into 20 sections
called plates.
• Plates include the crust and the top
part of the mantle.
• Plates float slowly on the “soupy” middle
part of the mantle.
How does the Earth’s crust move?
Moving plates. . .
1. Heated mantle rises toward the crust.
2. As it nears the crust, the mantle cools.
3. Cooling chunks of mantle are pushed
aside by heated mantle rising from below.
4. As the cooled mantle is pushed aside, it drags
along the plate floating on top of it.
5. The cooled chunk of mantle sinks back down,
and may be reheated and rise again.
The movement of the plates is called CONTINENTAL DRIFT.
How does the Earth’s crust move?
The plates move at
about the same
speed your
fingernails grow!
How does the Earth’s crust move?
Volcanoes, earthquakes, and mountains, oh my. . .
• The locations of volcanoes, earthquakes, and
mountains were identified on maps.
• Scientists noticed a pattern.
• These locations show us where the edges of
the plates can be found.
• These edges are called Plate Boundaries.
How does the Earth’s crust move?
See for yourself. . .
Volcanoes
Earthquakes
Plate Boundaries
How does the Earth’s crust move?
The “Ring of Fire”. . .
• Named
because of the
incredibly large
amounts of
active
volcanoes.
• Most of the
active
volcanoes on
Earth are
located here!
How does the Earth’s crust move?
Plate movement. . .
• The plates move in many different directions.
• Plate movement causes. . .
• New crust formation
• Mountains
• Volcanoes
• Earthquakes
How does the Earth’s crust move?
New crust formation. . .
• Occurs when plates move away from each
other
• Crust is formed by hot mantle rising up and
then cooling when it reaches the surface.
How does the Earth’s crust move?
Mountains. . .
• Occur when two plates carrying continental
crust collide
• Whole mountain ranges form this way.
• These mountains continue to grow (by
centimeters).
How does the Earth’s crust move?
Volcanoes. . .
• Occur when a plate carrying heavy ocean
crust collides with a plate carrying lighter
continental crust
• The heavier plate moves below the lighter
plate.
• The heavy plate begins to melt as
temperatures increase.
• The melted rock moved to the surface as
volcanic eruptions.
How does the Earth’s crust move?
Earthquakes. . .
• Occur when two plates straining against each
other move suddenly
• Plates are
connected at
faults.
• Earthquakes range
from small and hardly
felt to very large and
quite damaging.
Any
Questions?