Chapter 12 HW

Determine which type of heat transfer occurs in each layer or at each boundary. a. mantle b. d" layer c. outer core d. boundary between mantle and lithosphere e. inner core 1. Convection 2. Conduction 3. Both Convection and Conduction

1. Convection- a. mantle 2. Conduction- b. d" layer, e. inner core, d. boundary between mantle and lithosphere 3. Both Convection and Conduction- c. outer core

What is the Moho, and how is its depth determined? a. The Moho is the boundary between the crust and the mantle. Its depth is determined by observing where refracted seismic waves and direct seismic waves cross over each other. b. The Moho is the boundary between the mantle and the outer core. Its depth is determined by observing the reactions of seismic waves as they pass from one material into a different material. c. The Moho is the boundary between the crust and the mantle. Its depth is determined by observing the reactions of seismic waves as they pass from material of a solid state to material of a liquid state. d. The Moho is the boundary between the outer core and the inner core. Its depth is determined by observing the reactions of seismic waves as they pass from material of a liquid state to material of a solid state. e. The Moho is the boundary between the mantle and the outer core. Its depth is determined by observing where refracted seismic waves and direct seismic waves cross over each other.

a. The Moho is the boundary between the crust and the mantle. Its depth is determined by observing where refracted seismic waves and direct seismic waves cross over each other.

What characteristic of seismic waves makes them useful for probing Earth's interior? a. The velocities and directions of seismic waves reliably differ when they encounter different materials within Earth. b. All seismic waves travel through all of Earth's layers. c. All seismic waves travel only through solid rock. d. The paths of seismic waves are not altered when they meet new materials in Earth's interior. e. All seismic waves always move at the same velocity.

a. The velocities and directions of seismic waves reliably differ when they encounter different materials within Earth.

Why do seismic waves travel along curved paths through the mantle? a. because mineral phase changes in the upper mantle cause sudden increases in seismic velocity b. because the curvature of the seismic waves reflect the curvature of Earth c. because the velocities of seismic waves generally decrease with depth d. because mineral phase changes in the upper mantle cause a sudden decrease in seismic velocity e. because seismic wave velocities decrease as they pass through increasingly compact and rigid material

a. because mineral phase changes in the upper mantle cause sudden increases in seismic velocity

What is thought to produce Earth's magnetic field? a. As iron-rich fluid in the liquid inner core rises, the fluid is twisted by Earth's revolution around the Sun. The flow of this electrically charged material generates a geodynamo. b. As iron-rich fluid in the liquid outer core rises, the fluid is twisted by Earth's rotation. The flow of this electrically charged material generates a geodynamo. c. As iron-rich fluid in the liquid inner core and outer core rises, the fluid is twisted by Earth's rotation. The flow of this electrically charged material generates a geodynamo. d. As iron-rich fluid in the liquid inner core rises, the fluid is twisted by Earth's rotation. The flow of this electrically charged material generates a geodynamo. e. As iron-rich fluid in the liquid outer core rises, the fluid is twisted by Earth's revolution around the Sun. The flow of this electrically charged material generates a geodynamo.

b. As iron-rich fluid in the liquid outer core rises, the fluid is twisted by Earth's rotation. The flow of this electrically charged material generates a geodynamo.

How do the positions of the magnetic poles change through time? a. The magnetic north pole remains perfectly aligned with the geographic North Pole until the poles undergo a full reversal. During such a reversal, the magnetic north pole switches positions with the magnetic south pole. This reversal is caused by the vertical flipping of the outer core. b. The magnetic north pole varies somewhat from the geographic North Pole while still remaining in the Northern Hemisphere. Additionally, periods of full magnetic reversals have occurred where magnetic north and magnetic south have switched places with each other. Both types of variation are caused by changes in the convection patterns within the outer core. c. The magnetic declination remains perfectly aligned with the geographic North Pole until the poles undergo a full reversal. During such a reversal, the magnetic north pole switches positions with the magnetic south pole. This reversal is caused by the vertical flipping of the outer core. d. The magnetic inclination varies somewhat from the geographic North Pole while still remaining in the Northern Hemisphere. Additionally, periods of full magnetic reversals have occurred where magnetic north and magnetic south have switched places with each other. Both types of variation are caused by changes in the convection patterns within the outer core. e. The magnetic north pole remains perfectly aligned with the geographic North Pole until the poles undergo a full reversal. During such a reversal, the magnetic north pole switches positions with the magnetic south pole. This reversal is caused by changes in the convection patterns within the outer core.

b. The magnetic north pole varies somewhat from the geographic North Pole while still remaining in the Northern Hemisphere. Additionally, periods of full magnetic reversals have occurred where magnetic north and magnetic south have switched places with each other. Both types of variation are caused by changes in the convection patterns within the outer core.

Which of the following best describes what occurs during convection? a. Warmer, more dense material rises. b. Warmer, less dense material rises. c. Cooler, less dense material rises. d. Warmer, more dense material sinks. e. Cooler, less dense material sinks.

b. Warmer, less dense material rises.

The Moho separates the ______. a. the outer and inner core b. crust and mantle c. the lithosphere and asthenosphere d. the mantle and outer core e. the upper and lower mantle

b. crust and mantle

One-third of Earth's mass comes from ______. a. the asthenosphere b. the core c. the oceanic crust d. the mantle e. the lithosphere

b. the core

Which of the following best describes the pattern of heat flow through the lithosphere? a. Heat flow is high in the oceans. b. Heat flow is high on land. c. Heat flow is high where crust is being created. d. Heat flow is high where crust is old.

c. Heat flow is high where crust is being created.

What does a reflected wave tell us about Earth's interior? a. The wave has reached the opposite surface of Earth and is reflected back to the surface near the epicenter. b. The wave has passed by a curved boundary between two compositionally different layers within Earth, causing the wave to bend along its path. c. The wave has hit a boundary between two different Earth materials, causing it to reflect back to Earth's surface. d. The wave has reached the absolute center of Earth, causing it to reflect back to the surface. e. The wave has hit a boundary between two different Earth materials, causing it to continue its path through the boundary at a new angle.

c. The wave has hit a boundary between two different Earth materials, causing it to reflect back to Earth's surface.

What are the three compositionally distinct layers of Earth's interior? a. a weak crust at Earth's surface, a hot, pressurized mantle beneath the crust, and an iron-rich core that is made of a solid inner core and a liquid outer core b. a strong, rocky crust at Earth's surface, a hot, pressurized mantle beneath the crust, and an iron-rich core that is made of a liquid inner core and a solid outer core c. a strong, rocky crust at Earth's surface, a hot, pressurized mantle beneath the crust, and an iron-rich core that is made of a solid inner core and a liquid outer core d. a strong, rocky crust made of iron at Earth's surface, a hot, pressurized mantle beneath the crust, and an iron-rich core that is made of a solid inner core and a liquid outer core e. a strong, rocky crust at Earth's surface, a hot, iron-rich mantle beneath the crust, and a pressurized core that is made of a solid inner core and a liquid outer core

c. a strong, rocky crust at Earth's surface, a hot, pressurized mantle beneath the crust, and an iron-rich core that is made of a solid inner core and a liquid outer core

Why is the asthenosphere weaker than the lithosphere? a. The asthenosphere is warmer and has a higher viscosity than the lithosphere. b. The asthenosphere is cooler and has a higher viscosity than the lithosphere. c. The minerals that make up the asthenosphere are weaker than the minerals that make up the lithosphere. d. The asthenosphere is cooler and has a lower viscosity than the lithosphere. e. The asthenosphere is warmer and has a lower viscosity than the lithosphere.

e. The asthenosphere is warmer and has a lower viscosity than the lithosphere.

What causes a mineral phase change? a. the decrease of pressure on a mineral when it is moved deeper within Earth b. the increase of pressure on a mineral when it is moved closer to Earth's surface c. the heating of a mineral when it is moved closer to Earth's surface d. the increased heating of a mineral when it is moved deeper within Earth e. the increase of pressure on a mineral when it is moved deeper within Earth

e. the increase of pressure on a mineral when it is moved deeper within Earth