The Layers of the EarthThe Layers of the Earth

Look for patterns in these Look for patterns in these pictures of the inside of the pictures of the inside of the

Earth:Earth:

Why are there distinct Why are there distinct layers of the Earth?layers of the Earth?

•How are they different?•Depth•Temperature•State, (solid liquid or gas?)•Composition, (Iron? Aluminum?)

Layers of the EarthLayers of the Earth

Inner Inner CoreCore

Outer Outer CoreCore

MantleMantle CrustCrust

StateState SolidSolid LiquidLiquid ““Play-Play-Dough”Dough”

SolidSolid

ComponenComponentsts

Iron, Iron, Si, CSi, C

Iron, Iron, NickelNickel

MgO & MgO & SiOSiO2 2

Si, Si, Alum.Alum.

Distance Distance from from Surface Surface (km)(km)

6000 6000 (very centre (very centre of the earth)of the earth)

50005000 30003000 3535

Temp.Temp.o o CelsiusCelsius..

54005400 40004000 25002500 <60<60

The thickness of the crust The thickness of the crust varies:varies:

35 km thick

7 km thick

How do Scientists know so How do Scientists know so much about “the centre of much about “the centre of

the earth?”the earth?” Direct Evidence:Direct Evidence: Earth’s magnetic field suggests the Earth’s magnetic field suggests the

presence of iron;presence of iron;

More Direct Evidence:More Direct Evidence: The lava from volcanoes shows us what’s The lava from volcanoes shows us what’s

below the surface.below the surface.

Indirect Evidence:Indirect Evidence:

Scientists can Scientists can infer that the infer that the core is solid by core is solid by measuring measuring seismic waves.seismic waves.

Try this:Try this: Create… Create… 1) S-waves by 1) S-waves by

moving a slinky moving a slinky side to side;side to side;

2) P-waves by 2) P-waves by pushing the pushing the slinky.slinky.

Scientists create S and P waves at Scientists create S and P waves at one point on the crust, and one point on the crust, and

measure where they “come out” measure where they “come out” on the other side.on the other side.

Some seismic Some seismic waves don’t travel waves don’t travel through liquids, so through liquids, so when they don’t when they don’t show up on the show up on the other side of the other side of the earth, it suggests earth, it suggests there is liquid down there is liquid down there.there.

More Indirect Evidence:More Indirect Evidence:

The melting points of the minerals, (Iron, The melting points of the minerals, (Iron, Silicon, Aluminum, etc.) suggest the Silicon, Aluminum, etc.) suggest the temperatures of the layers.temperatures of the layers.

Some Melting Points,Some Melting Points,(degrees Celsius):(degrees Celsius):

Iron: 1535Iron: 1535 Carbon: 3600Carbon: 3600 Magnesium: 670Magnesium: 670 Nickel: 1452Nickel: 1452 Silicon: 1420Silicon: 1420

Use the table on the screen Use the table on the screen to complete the worksheet.to complete the worksheet.