Download 8.4 Earth`s Layered Structure

8.4 Earth’s Layered Structure
I. Layers Defined by Composition
 A) Earth’s interior consists of 3 major zones
(chemical composition).
8.4 Earth’s Layered Structure
Defined by Composition
 1)Crust
• a) Continental crust
- Upper crust composed of granitic rocks
8.4 Earth’s Layered Structure
 1)Crust
• b) Oceanic crust
- 1) Basaltic composition
- 2) Younger than the continental crust
8.4 Earth’s Layered Structure
 2) Mantle
• a) Below crust.
3) Core
• a) Below mantle
• b) Composed of an
iron-nickel alloy
• c) Really dense
8.4 Earth’s Layered Structure
II. Defined by physical properties
1) Lithosphere
• a) Crust and uppermost mantle (about 100 km
thick)
• b) Cool, rigid, solid
8.4 Earth’s Layered Structure
 2) Asthenosphere
• a)Beneath the lithosphere
• b) Upper mantle
• c) Soft, weak layer that is easily deformed
8.4 Earth’s Layered Structure
 3) Lower Mantle
• a) More rigid layer
• b) Rocks are very hot and flow like a milkshake.
8.4 Earth’s Layered Structure
8.4 Earth’s Layered Structure
 4) Inner Core
• a) Behaves like a solid
Fe & Ni
 5) Outer Core
• a) Liquid layer
• b) Convective flow of metallic iron within
generates Earth’s magnetic field
Earth’s Layered Structure
8.4 Earth’s Layered Structure
Discovering Earth’s Layers
ˇ´
 Moho- boundary
• Separates crust from underlying mantle
Earth’s Interior Showing
P and S Wave Paths
8.4 Earth’s Layered Structure
Discovering Earth’s Composition
 Crust
• Early seismic data and drilling technology
indicate that the continental crust is mostly made
of lighter, granitic rocks.
 Mantle
• Composition is more speculative.
• Some of the lava that reaches Earth’s surface
comes from asthenosphere within.