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EARTH’S LAYERED STRUCTURE
• The Earth is like an onion…it has many layers.
Earth’s Layers = Zones
• Earth’s interior
consists of 3
major zones:
– Crust
– Mantle
– Core
• Inner core
Crust
Mantle
Core
Inner Core
Zones defined by COMPOSITION
• Crust
– Thin, rocky
– Oceanic/
Continental
– Basalt and
Gabbro
– Average
composition is
called
granodiorite
– Density 3.0
gm/cm3
Crust
Zones defined by COMPOSITION
• Mantle
– 82% volume of
Earth
– Solid, rocky
– Periodotite
– Density 3.4
gm/cm3
Mantle
Zones defined by COMPOSITION
• Core
– Iron-nickle
alloy
– Density = 13
g/cm3
Core
Inner Core
Zones Defined by PHYSICAL PROPERTIES
• Lithosphere
– Cool, rigid
• Asthenosphere
– Soft, weak
• Lower Mantle
– More rigid, gradual
flow
• Outer Core
– Liquid
– Magnetic Field
• Inner Core
– Compressed solid
Lithosphere
Asthenosphere
Lower Mantle
Outer Core
Inner Core
MOHO!
Mohovorovicic discontinuity
• Discovered by
studying seismic
waves
• Separates crust
from mantle
• Lead to
discovery of
bending of
waves at core