Chapter 14

Question 1

Compressional Wave

Answer 1

A seismic wave that propagates by expanding and compressing the material it moves through.

Question 2

Mohorovic’ic’ Discontinuity

Answer 2

The boundary between the crust and the mantle, at a depth of 5 to 45 km, marked an abrupts increase in P-Wave velocity to more than 8 km/s. AKA Moho

Question 3

Convection

Answer 3

The mechanical transfer of heat energy that occurs as a heated material expands, rises, and displaces cooler material, which is itself heated and rises to continue the cycle.

Question 4

Paleomagnetism

Answer 4

The geologic record of ancient magnetization.

Question 5

Depositional Remanent Magnetization

Answer 5

A weak magnetization of sedimentary rock created by the parallel alignment of magnetic sediments particles in the direction of Earth’s magnetic field as they settle and preserved when the sediments are lithified.

Question 6

Phase Change

Answer 6

A transformation of a rock’s crystal structure by changing conditions of temperature and pressure, signaled by a change in seismic wave velocity.

Question 7

Geotherm

Answer 7

The curve that describes how Earth’s temperature increases with depth.

Question 8

Seismic Ray Path

Answer 8

The path along which seismic energy propagates Ray paths are perpendicular to waves fronts.

Question 9

Low-Velocity Zone

Answer 9

A layer near the base of the lithosphere, beginning at a depth of about 100 km, where S-wave speed abruptly decreases, marking the top part of the asthenosphere.

Question 10

Seismic Tomography

Answer 10

A technique that uses differences in the travel times of seismic waves produced by earthquakes and recorded on seismographs to construct three-dimensional images of Earth’s interior.

Question 11

Conduction

Answer 11

The mechanical transfer of heat energy by the jostling of thermally agitated atoms and molecules.

Question 12

Core-mantle boundary

Answer 12

The boundary between Earth’s core and its mantle, about 2890 km below the surface.

Question 13

Dipole

Answer 13

Pertaining to two oppositely polarized magnetic poles.

Question 14

Isostasy

Answer 14

A principle stating that the buoyancy force that pushes upward a lower-density body floating in a higher-density medium must be balances by the gravitational force that pulls it downward.

Question 15

Lower Mantle

Answer 15

A relatively homogeneous region of the mantle about 2200 km thick, extending from the phase change at about 660 km in depth to the core-mantle boundary,

Question 16

Shadow Zone

Answer 16

1. A zone beyond 105 degrees from the focus of an earthquake where S waves are recorded because they are not transmitted through Earth’s liquid outer core
2. A zone at angular distances of 105 to 142 degrees from the focus of an earthquake where P waves are not recorded because they are refracted downward into the core and emerge at greater distances after the delay caused by their detour through the core.

Question 17

Shear Wave

Answer 17

A seismic wave that propagates by moving the material it travels through from side to side Shares cannot propagate through any fluid – air, water, or liquid iron in Earth’s outer core.

Question 18

Thermoremanent Magnetization

Answer 18

Permanent magnetization of magnetizable materials align themselves in the direction of the magnetic field that exists when the material is hot and are then locked into place when the material cools below about 500 degrees.

Question 19

Transition Zone

Answer 19

The portion of the mantle bounded by two abrupt changes at depths of about 410 and 660 km.

Question 20

Upper Mantle

Answer 20

The portion of the mantle that extends from the Mohorovic’ ic’ discontinuity to the base of the transition zone at about 660 km in depth.