Plate Tectonics

Breakdown of the Earth Composition

Crust Mantle Core

Structure Lithosphere Asthenosphere Mesosphere Outer Core Inner Core

Crust Crust

Outer most layer 5 – 100 km thick Less than 1% of Earth’s mass

Continental Crust Minerals similar to granite, Less dense Average thickness 30 km

Oceanic Crust Similar to basalt 5 – 8 km thick

Mantle

Mantle Found between crust and core 2,900 km thick, 67% of Earth’s mass Contains iron and magnesium, similar to the

mineral Olivine Lithosphere: “rock sphere”

Outermost rigid layer 15 – 300 km thick Made of crust and upper part of mantle Divided into pieces known as “tectonic plates”

Mantle

Asthenosphere: “weak sphere” Soft putty layer on which the lithosphere

moves upon 250 km thick

Mesosphere: “middle sphere” Lower Mantle Strong interior structure 2,550 km thick

Core Core

Comprised of iron, nickel, sulfur and oxygen 3,428 km thick

Outer core Liquid layer 2,200 km thick

Inner core Solid layer 1,228 km thick

Liquid Rock of the Core Pressure allows rock to be solid Outer core has less pressure and is able

to spread out and become liquid. Class example

Tectonic Plates Pieces of the lithosphere that move

on top of the asthenosphere

How do scientists know about the structure of the Earth’s interior?

Measure different speed at which seismic waves travel.

Drilled to the center of the earth Volcanoes allow us to see into the

Earth Viewed satellite images from space