Chapter 22Earthʼs Interior

Section 22.1Earthʼs Structure

Objectives

Describe the science of geologyDescribe the main layers of Earthʼs

Interior.

How have scientists learned aboutEarthʼs Interior? Indirect measurements

Wave energy

Direct measurements Drilling

Deepest hole drilled was 12 km

The Science of Geology

Geology - the study of Earthʼs compositionand structure Composition - what itʼs made of Structure - how itʼs put together

Geologists Geo - Earth Ology - the study of Ists - people who

The Science of Geology (cont.)

Geologists categorize forces that change theEarth into: Destructive forces - break down/destroy Constructive forces - build/contruct

Modern Geology Began 1700ʼs James Hutton, scottish physican and farmer

The Science of Geology (cont.)

Hutton formed the principle ofUniformitarianism the forces acting on the Earth now are the

same ones that have existed I the past

A Cross Section of Earth

Like these “ScotchEggs”:Breading - crustWhite - mantleYellow - core

The Crust

Crust is made up ofsilicates (compoundsthat contain silicon andoxygen-quartz)

Continental crust -average depth of 40 km(8-75km) - made of lessdense rocks such asgranite

The Crust (cont.)

Oceanic crust -composed of moredense rocks such asbasalt

Average thickness of 7km

The Mantle

Hot but solid rock Temper and

pressure increasethe deeper you getinto the mantle

Rich in iron andmagnesium

Denser than crust

The Mantle (cont.)

3 layersLithosphere - cool,rigid rock (top layer)Aesthenosphere -softer, weaker rock withthe ability to flow (liketaffy)Mesosphere -stronger lower part ofthe mantle

The core Composed of iron

and nickel Temp. estimated to

be 5500 degreesCelsius

Outer core - liquidRotation creates anelectric current that inturn creates themagnetic field