Comparing the

Layers of Earth

S6E5.a.

Earth’s layers are compared by:

• Temperature

• Density – (the thickness or depth of the layer)

• Composition– What each layer is made of or how it is

described

Which is the outermost layer?

THE CRUST

Temperature:

Temp of the air outside to 1600 °F

Density: 5km – 70km thick

The Crust: What’s it made of?

• 2 types of crust:

– Oceanic – mostly basalt rocks

The thinnest crust

– Continental – mostly granite rocks

The thicker crust

What do you find on Earth’s crust?

• Rocks

• Mountains

• Soil

• Water

• What else???

Where the Crust ends and the Mantle begins is an area called

the MOHO Discontinuity.

1909: Andrija Mohorovicic discovers the moho discontinuity, which is the boundary between Earth’s crust and mantle.

Next is the Mantle…• Mantle Temperature range:

From 1600 °F to 6700 °F

• Density of the WHOLE Mantle = 2867 km!

–Let’s break it apart!

The Mantle• Made of 3 distinct

areas:

–Lithosphere

–Asthenosphere

–Lower Mantle

Mantle’s Lithosphere• Density =

approx 100 km

• Composition:

–Rigid layer

–Rocky like Crust

–“Lithos” means “Stone”

• Unique? Made up by part of the Crust!

Mantle’s Asthenosphere• Density = 300 km

• Composition:

– Plastic-like– Solid, but softer– “Asthenes” means “weak”

– Unique? Makes the plates move! Because it’s slowly flowing.

Lower Mantle• Density = 2467 km

• Composition:– Solid

Unique? Semi-rigid

Where the Mantle ends and the Outer Core begins is an area

called the GUTENBERG DISCONTINUITY

Gutenberg Discontinuity

Outer Core

• Temperature = 6700 °F to 7800 °F

• Density = 2266 km

• Composition:– Liquid, Molten Metal

(Fe & Ni)

What makes the Outer Core unique?

• Creates Earth’s magnetic field

• High temps from the formation of the planet keep the Iron (Fe) & Nickel (Ni) liquid

Inner Core• Temperature = 7800 °F to

13000 °F

HOTTEST LAYER!!!

• Density = 1216 km

• Composition:– Dense, solid metal ball of Fe & Ni!

What’s unique about the Inner Core?

• Extreme pressure squeezes the atoms of the Fe & Ni so much, they cannot spread out!

• Stays solid!