Chapter 9 Earths Interior.pptx - Chapter 9: Earth’s...

Chapter 9: Earth’s Interior

Crustal
Composition
•
98.5% of the crust is
comprised of just eight
elements.
•
Oxygen is the most
abundant element in the
crust.
•
This reflects the
importance of silicate
(SiO
4
) minerals.
•
Oxygen is large. It
occupies ~93% of
crustal volume.

Earth Layers
Classified by
Chemical
Composition
•
CRUST
•
is sampled directly by drilling and
is studied extensively by seismic
analysis.
• It is the thin relatively lightweight
outermost layer
•
it is a rigid layer
•
makes up .4% of the earth’s total
mass
• less than 1% of its volume.
• The crust is divided into OCEANIC
CRUST and CONTINENTAL CRUST

Types of
Crust
• OCEANIC CRUST
• Mafic composed primarily of BASALT and GABBRO
• which is a heavy, dark colored rock composed mostly of oxygen, silicon, magnesium and iron
•
Average density of approximately 3.0 g/cm3
•
Average thickness of 7-10 km
• CONTINENTAL CRUST
• Felsic, average composition of GRANITE
•
which is a speckled rock composed mainly of oxygen, silicon and aluminum
•
Average density of approximately 2.7 g/cm3
•
Average thickness of 35-40 km

Earth Layers
Classified by
Chemical
Composition
• MANTLE
• Is the layer beneath the crust
• Makes up 68.1% of the earth ’ s mass and
83% of its volume
• Composed of oxygen, magnesium and
silicon
• Density varies with depth from 3.3-5.5
g/cm
3
with an average being 4.5 g/cm
3
• 2900 km in thickness
•
Divisions
•
Upper Mantle down to a depth of
660 km
•
Lower Mantle from 660 km down
to 2,900 km
•
Transition Zone is the section
between 400 km and 660 km deep

Earth Layers Classified by Chemical
Composition
• CORE
•
Is the innermost layer
•
Makes up 31.5% of the earth ’ s mass and 16% of its
volume
•
Composed of 90% iron and nickel along with
silicon, sulfur, and heavy elements
•
Metallic central zone
•
Average density is 13 g/cm
3
•
3470 km in thickness
• Divided into two parts
• OUTER CORE
• viscous liquid,
with a density of
11.8 g/cm3
• Flow generates the
Earth’s magnetic field
•
INNER CORE
•
solid with a density
of 16 g/cm3

Earth Layers Classified