Post on 16-Dec-2015
Inside Edition
The Earth’s Interior:
A Hot Topic
A Planet at Rest?From the surface or from space the earth appears stable and calmExcept for infrequent violent volcanic and earthquake activity the earth hides its volatile natureThe key to understanding this side of the earth is understanding its interior
A Model of the Earth
Inner CoreOuter CoreMantleCrust
DifferentiationRemember how the Earth
Formed?
The Nebula Hypothesis
Planetesimals joined together to form protoplanets which were molten, at first
Dense materials like iron and nickel would tend to sink towards the middle
As cooling progressed lighter materials floated to the surface like “scum” and formed the crust
This was all completed about 4 billion years ago
Inner Core1216km (754 miles) in radiusRich in Iron and NickelIntense Pressure and Heat:
37000c (67000 f)
Dense materials sank to core as earth cooledSolid
Outer Core2270km (1410miles) thick Molten Iron and Nickel1500ºcLess pressure than inner coreliquidInner and outer core = 1/6 volume, but 1/3 mass
Mantle2900km (1800miles) thick Mainly Fe, Mg, Si, and OAbout 1200ºcMakes up 2/3 of Earth’s massLess pressure than cores, but still pretty intensePlasticlike-partially molten compostion that can slowly “flow”
Crust30-40km(19-25miles) average thicknessBeneath mountains can reach 43 milesThis thin layer that floats on denser mantleAverage composition is basalticSolid – Made of Plates•if you were to imagine the Earth as a soccer ball, the crust would be about ½millimeter thick.
The Thickness of the Crust Varies:
•This is a contour map of the thickness of the Earth's crust. The contour interval is 10 km; it also include sthe 45 km contour for greater detail on the continents.
•Where are the thickest parts of the crust?
Rock SolidContinental Crust
Thickest type of crust;- can be 43 miles thick beneath mtns.Very old rocks, 3.8 billion years oldLighter granitic composition
Do You Want Some Water With
That Crust?Oceanic Crust
Thinnest part of the crust, 4-7 miles thickRocks are relatively young, only 200 million years oldDense basaltic composition
Crust and Mantle
Lithosphere – cool, rigid upper layer of earthAsthenosphere – softer layer of the earth under the lithosphereMesosphere – very slowly flowing layer under the asthenosphere
The interaction of the crust and mantle gives rise to tectonic activity and crustal movement
The crust and mantle are broken down into three different zones
LithosphereComposed of the Crust and upper mantle
Solid – rigid plates made of the lithosphere
Varies from a few to 190 miles thick (62 miles average)
Continental CrustOcean Water
Upper MantleLithosphere
Oceanic Crust
AsthenosphereVery hot, weak zone of the upper
mantle capable of flowing
Temperatures reach 26000F – hot enough to melt some of the mantle material
This creates a soft layer about 200 miles thick that the overriding lithosphere “floats” upon
The lithosphere can move independently of the asthenosphere
So What?
Why is this important to
know?
The movement of the lithosphere created
because of the uneven heating of the interior of the earth causes many
things, like….
Earthquakes
And……
Volcanoes
Coloring the Earth’s Plates:
Color each plate a different color
•Be sure can still see the arrows showing the direction the plates are moving
•Answer the questions associated with the map