Earth Layers

Seismic Waves Scientists know that the Earth consists of layers ●this is known by studying seismic waves ●if the Earth was not layered, seismic waves would travel straight through at constant speed… ●this is NOT the case

Earth Layers Four Major Layers   1.) Crust – the thin, cool, rocky outer layer ●two types – Continental and Oceanic Thick (40km) Old (up to 4 byo) Thin (7km) Young (less than 180 myo)

Mantle 2.) Mantle – ●Upper mantle is similar to the crust (mostly solid rock) ●Lower mantle is warm and soft ●magma rises and lowers, creating convection currents

The Core 3.) Outer Core ● Hot and Liquid Flowing iron produces Earth’s magnetic field 4.) Inner Core ● Hottest layer SOLID iron-nickel sphere Solid due to immense pressure

Lithosphere & Asthenosphere ● cool solid outer layer of Earth ►consists of crust and uppermost mantle Asthenosphere ● warm, soft and weak layer of Earth ►consists of the lower mantle

Moho Mohorovicic Discontinuity ● The separation between the crust and the mantle ● Shortened to Moho ● Discovered in 1909 by seismologist Andrija Mohorovicic ● Discovered it by studying seismic waves