Question 1

The graphical curve that describes how temperature changes with depth in Earth is called the

Accepted Answer

A) tempotherm. 
B) heating gradient. 
C) geoid gradient. 
D) geotherm.

Question 2

Earth's magnetic field shields the surface of Earth from

Accepted Answer

A) asteroids. 
B) solar winds. 
C) intergalactic radio waves. 
D) geotherms.

Question 3

Why is the average elevation of the continents higher than the average elevation of the seafloor?

Accepted Answer

A) because melting of large ice caps has caused isostatic rebound of the continents 
B) because oceanic crust is composed of denser rocks than the continental crust 
C) because the continents are supported by upwelling mantle currents 
D) because subduction pulls down the seafloor

Question 4

Where do P waves travel fastest?

Accepted Answer

A) in the upper mantle 
B) in the outer core 
C) in the lower mantle 
D) in the inner core

Question 5

What drives plate tectonics?

Accepted Answer

A) erosion 
B) solar energy 
C) thermal conduction 
D) thermal convection

Question 6

Where is Earth's magnetic field generated?

Accepted Answer

A) in the crust 
B) in the mantle 
C) in the outer core 
D) in the inner core

Question 7

Given that the P wave velocities are related to rock density,choose the sequence that shows the rocks in terms of increasing P wave speeds.Rock densities are: rock I = 2.9 gm/cc,rock II = 2.6 gm/cc,and rock III = 3.3 gm/cc.

Accepted Answer

A) I,II,III 
B) II,III,I 
C) I,III,II 
D) II,I,III

Question 8

At what depth does the transition from the upper mantle to the lower mantle occur?

Accepted Answer

A) approximately 100 kilometers 
B) approximately 3000 kilometers 
C) approximately 700 kilometers 
D) approximately 5000 kilometers

Question 9

Using a compositional model of pure iron-nickel alloy for the inner core renders the inner core ________ to match the data for the outer core.

Accepted Answer

A) too dense 
B) not dense enough 
C) too magnetic 
D) not magnetic enough

Question 10

How much of Earth's magnetic field can be described by a simple dipole?

Accepted Answer

A) 10% 
B) 25% 
C) 75% 
D) 90%

Question 11

Seismic tomography has revealed that seismic waves in the uppermost mantle are relatively

Accepted Answer

A) fast beneath both mid-ocean ridges and subduction zones. 
B) fast beneath mid-ocean ridges and slow beneath subduction zones. 
C) slow beneath mid-ocean ridges and fast beneath subduction zones. 
D) slow beneath both mid-ocean ridges and subduction zones.

Question 12

The area on the surface of Earth where P waves and S waves are not recorded by seimograms following an earthquake event are referred to as

Accepted Answer

A) reflection zones. 
B) aseismic areas. 
C) geoid highs. 
D) shadow zones.

Question 13

What sort of geothermal gradient is consistent with having convection in the mantle?

Accepted Answer

A) 0.5°C/km 
B) 2.5°C/km 
C) 25°C/km 
D) 250°C/km

Question 14

The temperature at the center of Earth is approximately

Accepted Answer

A) 200°C. 
B) 500°C. 
C) 2000°C. 
D) 5000°C.

Question 15

Which of the following statements is false?

Accepted Answer

A) S waves slow down as they travel through the mantle. 
B) P waves slow down in the outer core. 
C) S waves cannot transmit through the outer core. 
D) P waves travel through the inner core.

Question 16

Exploring Earth's interior using seismic tomography is analogous to exploring the human body using a(n)

Accepted Answer

A) CAT scanner. 
B) MRI machine. 
C) stethoscope. 
D) fMRI machine.

Question 17

Earth's magnetic field would disappear if

Accepted Answer

A) Earth stopped rotating. 
B) the outer core grew larger. 
C) plate tectonics stopped. 
D) the outer core solidified.

Question 18

When was there a 35-million-year period during which Earth's magnetic field did not undergo reversals?

Accepted Answer

A) the Cretaceous 
B) the Eocene 
C) the Miocene 
D) the Pliocene-Pleistocene

Question 19

As seismic waves travel through Earth,they generally

Accepted Answer

A) curve upward. 
B) travel in straight lines. 
C) curve downward. 
D) travel along irregular paths.

Question 20

Which of the following correctly lists the three rock types in order of increasing P-wave velocity?

Accepted Answer

A) gabbro.granite,peridotite 
B) granite,peridotite,gabbro 
C) granite,gabbro,peridotite 
D) peridotite,gabbro,granite

Exam 14: Exploring Earths Interior