Chapter 7 Section 1
Inside the Earth
Compositional Layers of the Earth
(Brown)
(Gray/green)
Composition of the Earth:
The Earth is divided into 3 compositional layers:
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Core:
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Mantle:
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iron, nickel
magnesium, iron, aluminum, silicon, oxygen
Crust:
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oxygen, silicon, aluminum, iron, calcium, & magnesium
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Crust and mantle are not very dense.
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Core is denser than the crust & mantle.
Compositional layers of Earth
CRUST
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The outermost layer
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5-100 km thick
Thinnest layer
2 types of crust
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Continental- thick
Oceanic-thin
MANTLE
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2900 km thick
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Layer between the crust and
core
Thicker than crust
Contains most of Earth’s
mass
Scientists study the mantle
by looking at the
composition of magma.
Magma from volcanoes
gives scientists clues about
the composition of the
mantle.
How scientists see the mantle

Volcanic eruption of Mt. Etna in Sicily
CORE

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Innermost layer, below
mantle to center of
Earth
Made mostly of iron
and nickel
Divided into two parts
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Inner core—solid
Outer core—liquid
Physical Properties of Earth: How the layers
respond to heat and pressure
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Earth divided into 5 physical (mechanical) layers:
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Lithosphere
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Asthenosphere
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Mesosphere
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Outer Core

Inner Core
Lithosphere
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Outer layer of Earth
Made of crust & rigid, upper mantle
(asthenosphere)
Divided into pieces called tectonic, or
continental plates
Continental plates drift slowly—a few
centimeters a year—on top of the
mantle
Asthenosphere
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Layer below
lithosphere
Pieces of
lithosphere (tectonic
plates) move along
this layer
Made of solid rock,
soft, plastic-like
layer of the mantle
Mesosphere
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Below the
asthenosphere
Strong lower
part of mantle
Extends to the
Earth’s core
Outer Core
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Liquid layer
of Earth’s
core
Surrounds
inner core
Inner Core
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Solid dense
center
Quiz
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1. What are the three compositional layers of
the Earth?
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2. What are the physical layers of the Earth?
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3. Is the mantle solid or liquid?
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4. What physical and compositional layers of
the Earth do you live on?
Quiz Answers
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1. What are the three compositional layers of the
Earth? Crust, Mantle, and Core (CMC)
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2. What are the physical layers of the Earth?
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Lithosphere, Asthenosphere, Mesosphere, Outer Core, and
Inner Core
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3. Is the mantle solid or liquid? Liquid that can be
forced to act as a solid
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4. What physical and compositional layers of the Earth
do you live on?
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Physical: lithosphere
Compositional: Crust