Chapter 12

Question 1

Mineral Phase Change

Answer 1

A change that occurs when a mineral is subjected to intense pressure; in this change, the structure of a mineral may become unstable, causing its atoms to rearrange into a denser, more stable structure.

Question 2

Seismic Reflection

Answer 2

The redirection of some waves back to the surface when seimic waves hit a boundry between different Earth materials.

Question 3

Wave Refraction

Answer 3

A change in direction of waves as they enter shallow water. The portion of the wave in shallow water is slowed, which causes the waves to bend and align with the underwater contours.

Question 4

Crust

Answer 4

The very thin outermost layer of Earth

Question 5

Mohorovicic (Moho)

Answer 5

The boundry seperating the crust and the mantle, discernible by an increse in seismic velocity.

Question 6

Mantle

Answer 6

One of Earth’s compositional layers. The solid rocky shell that extends from the base of the crust (Moho) to a depth of 2900 kilometers (1800 miles) the liquid core.Upp

Question 7

Upper Mantle

Answer 7

Extends from the Moho to a depth of about 660 kilometers and can be divied into 3 shells: lithospheric mantle, asthenosphere, and the transition zone.

Question 8

Lithospheric Mantle

Answer 8

• Uppermost mantle
• This layer and the crust make up Earth’s rigid outer shell called the lithosphere
• a few kilometers to as thick as 200 kilometers

Question 9

Asthenosphere

Answer 9

A subdivision of the mantle situated below the lithosphere.

• This zone of weak materal exhists below a depth of about 100kilometers and in some regions extends as deep as 700 kilometers
• The rock within this zone is easily deformed.

Question 10

Transition Zone

Answer 10

• the lower protion of the upper mantle

- at depths between 410 and 660 kilometers

Question 11

Lower Mantle (Mesosphere)

Answer 11

• lies between the transition zone and the liquid core

- beneath 660 kilometers

Question 12

The D” Layer

Answer 12

• the boundry layer between the rocky mantle and the liquid iron outer core
• thought to have large variations in compostione and temperature

Question 13

Shadow Zone

Answer 13

The zone between 105 and 140 degrees from an earthquake epicenter. Direct waves do not penetrate the shadow zone because of refraction by Earth’s core

Question 14

Outer Core

Answer 14

A layer beneath the mantle about 2270 kilometers thick which has the properties of a liquid

Question 15

Core

Answer 15

• The innermost layer of Earth

- It is thought to be largly an iron-nickle alloy, with minor amounts of oxygen, silicon, and sulfur

Question 16

Inner Core

Answer 16

• The solid innermost layer of Earth

- about 1216 kilometers in radius

Question 17

Convection

Answer 17

The transfer of heat by the mass movement or cirulation of a substance

Question 18

Viscosity

Answer 18

A measure of a fluids resistance to flow

Question 19

Mantle Plumes

Answer 19

A mass of hotter-than-typical manlte material that ascends towardss the surface, where it may lead to igneous activity. These plumes of solid yet mobile material may originate as deep as the core-mantle boundry

Question 20

Conduction

Answer 20

The transfer of heat through matter by molecular activity

Question 21

Geothermal Gradient (Geotherm)

Answer 21

The gradual increase in temperature with depth in the crust.
-The average is 30 degrees C per kilometer in the upper crust

Question 22

Seismic Tomography

Answer 22

collecting signals from many different earthquakes recorded at many seismogrph stations, in order to “see” all parts of Earth’s interior

Question 23

Geodynamo

Answer 23

As iron-rich fluid in the outer core rises,
its path becomes twisted because of Earth’s rotation. As a result, the fluid moves in spiraling columns that align with Earth’s axis of rotation.
Because the iron-rich fluid is electrically charged and flowing, it generates a magnetic field