Earth’s Layered Structure

Important Statistics The earth is not a sphere; it is an oblate spheroid (wider at the equator) Hydrosphere: 71% of earth’s surface 97% is oceans 3% is lakes/rivers

Two Types of Crust 1. Continental Crust about 30% of the Earth Thickest layer (mountains) Less dense made of Felsic Igneous rock (sits higher than ocean water almost floating) Rich in silicon Most abundant mineral is quartz-very hard

Two Types of Crust Cont… 2. Oceanic Crust About 70% of the Earth Thin layer & youngest Dense made of Mafic (dark color) Igneous rock Rich in Iron and Magnesium Most abundant mineral is basalt

Layers of the Earth’s Interior Lithosphere Outer layer of the Earth (crust & upper- mantel) Crust- solid, outermost layer (continental/oceanic) This layer sits on the mantle.

Layers of Earth’s Interior Asthenosphere 200 km zone of mantle where rock is hot enough to flow (this includes the mantle) Mantle: 2870 km thick layer below crust (largest layer) made of a liquid plastic magma Outer Core: liquid layer of iron that generates the Earth’s magnetic field Inner Core: solid iron compressed from super high pressure

The Layers of the Earth

The Earth’s Interior The earth is made up of layers. Studied by seismic waves. Seismic waves change speeds through different layers.

Proof of Layers Seismic waves zones on earth’s surface where seismic waves can’t be detected – P-waves: fastest waves, deflect through inner core. (hit inner core and deflect away) solids and liquids – S-waves: second fastest waves, don’t pass through outer or inner core. (absorbed by outer core) only through solids

*only p waves can travel all the way through earth and s waves will hit a liquid layer and be deflected so we can predict what certain layers of Earth are liquid and others solid

The Earth as a Magnet Earth has North and South magnetic poles. Results from liquid iron in outer core. Movements in the outer core create a magnetic field.