Earth's Interior

Earthquakes release

energy that moves as waves

The velocity of waves depends on

the density of the rock they move through

Some earthquake waves don’t move through
liquids, others do but are

refracted

Tools to figure out the composition of the Earth’s interior:

• Examine magma and lava, figure out what depth inside the Earth they came from

• Figure out what materials have densities that match the calculated densities for the interior units

• Use the composition of meteorites (chunks
  of material that fell to Earth from space)

90% of Earth is made of four elements

• Iron (Fe) - Majority

• Oxygen (O)

• Silicone (Si)

• Magnesium (Mg)

Major Layers of the Earth

1. Crust

2. Mantle

3. Core

What are the two types of crust?

Continental crust and Oceanic crust

What is the continental crust mostly made of?

mostly granitic: less dense

What is the oceanic crust mostly made of?

mostly basaltic: more dense

Granite

high in silicon, low in iron and magnesium

Basalt

low in silicon, high in iron and magnesium

Overall composition of the crust

Oxygen is the most abundant element

Silicon #2 Earth’s interior

What is the mantle mostly made of?

Peridotite

Mantle

Middle layer

Almost the entire mantle is solid, but below [~100-

150 km], it’s so hot that it’s soft:

2 parts of the Mantle

Upper and Lower

geothermal gradient

Rate of temperature increase with depth

Crust-mantle boundary is called the

Moho

What is the outer core made of and what is its phase?

Liquid iron alloy (iron, nickel, other elements)

What is the inner core made of and what is its phase?

Solid iron (with some nickel/other stuff)

Why is the outer core liquid but the inner core solid?

Pressure

What are the two behavioral layers of the outer Earth?

Lithosphere and Asthenosphere

How well does the lithosphere flow?

Rigid, can’t flow easily

How well does the asthenosphere flow?

Less rigid, can flow easily

Lithosphere

crust and upper portion of mantle

Asthenosphere

lower portion of mantle