The Layers of the Earth Earth Layers The

The Layers of the Earth!

Earth Layers * The Earth is divided into four main layers. *Inner Core *Outer Core *Mantle *Crust

The Crust * The Earth’s crust is like the skin of an apple. It is very thin compared to the other three layers. *The crust makes up 1% of the Earth. * The crust of the Earth is broken into many pieces called plates.

The Crust * Outer layer * 5 -100 km thick * 2 types of crust – Oceanic (very dense, made of basalt) – Continental (less dense, made of granite)

Oceanic and Continental Crust

The Mantle * The mantle is the layer below the crust. * The mantle is the largest layer of the Earth. * The mantle is divided into two regions: the upper and lower sections.

The Mantle, continued • The upper mantle is further divided into 2 parts 1) The very top of the mantle is relatively cold & is rigid, so it is included with the crust and known as the lithosphere

The Upper Mantle, cont. • 2) Just below the rigid lithosphere, there lies a layer of softer, weaker rock that is semi-solid— it flows VERY slowly • It is known as the asthenosphere • This is where the magma from volcanoes comes from.

Mantle Magma & Convection Currents • The semi-solid rock at the top of the asthenosphere cools down, becomes more dense, & starts to sink. • The warmer, less dense magma rises up. • Convection currents are set up.

Mantle Magma & Convection Currents • The semi-solid rock at the top of the asthenosphere cools down, becomes more dense, & starts to sink. • The warmer, less dense magma rises up. • Convection currents are set up.

Lower Mantle The lower mantle

The Core * Made mostly of iron * 1/3 of the earth’s mass * Very hot

Outer Core * The core of the Earth is like a ball of very hot metals. * The outer core is liquid. * The outer core is made up of iron and is very dense.

Inner Core * The inner core of the Earth has temperatures and pressures so great the metals are squeezed together and are not able to move. * The inner core is a solid.

Earth’s Layers * How are the earth’s layers similar to an egg? * Shell=crust * Egg white=mantle * Yolk=core

Physical Structure of the Earth (5 Layers) * Lithosphere- rigid outer layer (crust and very top of mantle); sits on top of asthenosphere * Asthenosphere- solid rock that flows slowly (like hot asphalt) in the upper & middle part of the mantle * Mesosphere- middle layer – lower mantle rock that is hotter but harder than asthenosphere * Outer Core- liquid layer * Inner Core- solid, very dense

Tectonic Plates * Earth’s crust is broken into about 19 pieces * These plates move on top of the asthenosphere

Review 1) What are the four layers of the Earth? 2) The Earth’s crust is very ______? 3) The mantle is the largest layer of the Earth? True or False 4) Is the Outer Core a liquid or a solid?

Answers! 1) Crust, Mantle, Outer Core, Inner Core 2) Thin 3) True 4) Liquid