Chapter 14: Earth's Interior

Question 1

What are the three primary layers of the earth and the depth at which they end?

Answer 1

Lithosphere (100 km) - rigid

• Crust
• Upper mantle

Mantle (2800) - plastic

• Asthenosphere
• Lower mantle

Core (3481 km)

• Outer Core (liquid)
• Inner Core (solid)

Question 2

How is the Earth structured and why?

Answer 2

Earth consists of series of concentric layers or spheres which differ in chemical and physical properties. Structured this way because of density stratification.

Question 3

How Do We Really Know What Earth’s Interior Looks Like?

Answer 3

Rock Sampling & Drilling (12.5 km max)
Meteorites
Seismic Studies
Xenoliths and Volcanism

Question 4

Purpose of seismic surveys

Answer 4

Help us study the subsurface of the earth

Question 5

Earth’s layered structure discovered using changes in _______.

Answer 5

Seismic wave velocity

Question 6

Differential speed of seismic/sound waves due ot density differences. The two types are:

Answer 6

Pressure Waves (P, fast) - parallel to direction of motion and travel through liquids.

Shear Waves (S, slow) - perpendicular to direction of motion and do not travel through fuids (liquid or gas)

Seismic waves refract and reflect at density boundaries within Earth.

Question 7

Seismic wave speed varies as a function of what

Answer 7

Depth and density of the material is is traveling through.

Question 8

Seismic shadow zones

Answer 8

P waves can’t reach surface from 105˚ to 142˚ because of the way they’re refracted when they enter and leave core.

S waves can’t reach surface from 105˚ to 180˚ bc they can’t travel through outer core.

Question 9

Physical properties of the lithosphere

Answer 9

Crust and uppermost mantle (~100 km thick)
Cool, rigid, solid

Question 10

Asthenosphere

Answer 10

Beneath lithosphere
To a depth of 200-400 kilometers (maybe 660 km)
Soft, weak layer
Easily deformed

Question 11

Lower Mantle

Answer 11

(below asthenosphere)
From 600 to 2900 km depth
More rigid layer
Rocks are very hot and capable of gradual flow (convection)

Question 12

Outer core

Answer 12

Liquid layer
2900 – 5150 km depth
Convective flow of iron
Generates Earth’s magnetic field

Question 13

Inner Core

Answer 13

5150 – 6371 km depth
Behaves like a solid

Question 14

Composition of oceanic crust. mantle. and core

Answer 14