Earth's Internal Structure and Plate Tectonics

Core

Innermost layer of Earth, consisting of iron.

Mantle

Middle layer, composed of semi-solid rock.

Crust

Thin outer layer of Earth's surface.

Asthenosphere

A soft, hot layer of the Earth’s mantle below the crust that slowly flows and allows tectonic plates to move on top of it.

Lithosphere

Rigid outer layer, includes crust and upper mantle.

Inner Core

Solid iron center, high pressure and heat.

Outer Core

Liquid layer generating Earth's magnetic field.

Gutenberg Discontinuity

Boundary between core and mantle.

Mohorovicic Discontinuity

Boundary separating crust from mantle.

Continental Crust

Thicker crust, primarily granite composition.

Oceanic Crust

Thinner crust, primarily basalt composition.

Seismic Waves

Waves used to study Earth's interior.

Pangaea

Supercontinent that existed 200 million years ago.

Continental Drift

Theory proposing continents move over time.

Convective Currents

Movement in asthenosphere causing plate motion.

Divergent Boundaries

Plates move apart, creating new crust.

Convergent Boundaries

Plates collide, leading to subduction zones.

Transform fault Boundaries

Plates slide past each other without creation. Help move segments of a mid-ocean ridges

Subduction

Process where one plate sinks beneath another.

Oceanic-Continental Convergence

Denser oceanic plate subducts under continental.

Oceanic-Oceanic Convergence

Older oceanic plate subducts, forming islands.

Continental-Continental Convergence

Continents collide, forming mountain ranges.

Mid-Ocean Ridge

Underwater mountain range formed by divergent boundaries.

Earthquake Zone

Area where tectonic plate movement causes earthquakes.

Himalayas

Mountain range formed by continental-continental convergence.

Challenger Deep

Deepest point in Earth's oceans, 11,035 m below sea level.

Rates of Plate Movement

Tectonic plates move 2-15 cm/year.

Cratons

Stable portions of continental crust, tectonically inactive.

Where does plate activity occur

Plate activity mostly occurs at plate boundaries, where the edges of tectonic plates meet. Here's what happens at each type:

How do we know about Earth’s internal structure

Seismic waves

from earthquakes

• Deep wells

Three parts of the Solid Earth

Crust, mantle Core.