Download Earth`s layers

Earth’s Systems
Movement of the Earth’s Crust
Earth’s Layers
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There are three main
layers of Earth.
The Earth’s outermost
layer is the crust.
The layer directly
beneath the crust is the
mantle.
The innermost layer is
the core.
Layer Descriptions
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The Inner core: Mainly
iron, solid, extremely
hot, high pressure.
The Outer
Core:Extremely hot
liquid metals, mainly
iron and nickel.
Mantle:High
temperatures only
partially melt metal here
because of high
pressure.
Layer Description
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Asthenosphere: Part of
the upper mantle that is
partial melted rock.
Lithosphere: Upper
mantle and lower crust,
floats on the
asthenosphere, cool
and solid.
Crust: Thinnest layer of
Earth. Mainly granite
but under oceans
mainly basalt.
Earth’s Plates
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The lithosphere has seven
major plates (see map on
pg..D8-D9).
These plates can flow
(plasticity) in the
asthenosphere.
Heat in the center of the
Earth causes currents and
hot mantle is pushed up by
cooler rock.
The rock spreads, cools and
sinks again.
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These plates are constantly
moving and changing shape.
Plates sometimes split or
combine with another plate.
Sometimes plates slide under
another plate to become
mantle rock again.
The boundaries where plates
meet are usually the sites of
earthquakes and volcanoes.
Plate Tectonics
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Plate tectonics is the
theory scientist use to
explain plate
movements.
Major plates are named
for the continents or
oceans they carry.
Ocean crust is newer
and thinner then that of
the continents.
See page D8-D9.
Changes to the Earth’s Surface
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Plate movement causes
the Earth’s surface to
change.
They form mountains,
cause earthquakes and
volcanic eruptions.
Meteors, glaciers, wind
and water are other
factors that can change
the Earth’s surface.
Summary
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Earth is composed of core, mantle and crust.
The crust makes up the lithosphere where
Earth’s land and oceans are found.
Plate tectonics explains how the plates move
around causing changes to the Earth’s
surface.
Other changes in the Earth’s surface come
from glaciers, wind, water and meteors.