Chpt. 1 - Plate Tectonics

Layers of the Mantle

Lower mantle, asthenosphere, lithosphere

Plates

Broken up pieces of the lithosphere. Slide on top of the asthenosphere.

SIAL

Silica + Alumina

SIMA

Silica + Magnesium

Endogenic forces

Forces from within the Earth that cause the crust to move vertically or horizontally. Convection currents in the Mantle are mainly responsible for this.

Moho line

Invisible boundary between solid upper mantle and the Earth’s crust

Oceanic crust

8km thick

Made of light rock e.g. granite

SIAL

Continental crust

45km thick

Made of heavy rock e.g. Basalt

SIMA

Asthenosphere

100-200km thick

Semi-molten rock

Allows solid rock to slide on it

Lithosphere

50-200km thick

Solid, rigid but brittle rock

Slides into the asthenosphere