earth 22.1
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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
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