Deck 10: Deformation,Mountain Building,and Earth's Crust

Question 1

What type of information is found on geologic maps,and what are some of the possible uses for geologic maps?

Answer 1

Geologic maps include information on the distribution of rock types,age relationships among rock units,and geologic structures.Uses are varied.Economic uses include locating petroleum,ore deposits,and sand and gravel deposits; hazard planning includes locating potential volcanic activity,landslides,and earthquake faults; city planning includes placing landfills; and engineering uses includes placing dams,highways,nuclear reactors,and tunnels.

Question 2

What are the three types of stress?

Answer 2

compression,tension,and shear stress

Question 3

What is isostatic rebound? Give an example.

Answer 3

Isostatic rebound is the re-equilibration of the crust by rebounding to the level at which it "floats" again in the mantle after a mass has been removed.The melting of glaciers after the end of the ice age has caused the crust they were sitting on to rebound upward.

Question 4

What is the difference between a thrust fault and a reverse fault?

Question 5

What role do geologists play in engineering large structures like bridges and power plants?

Question 6

What are some ways in which mountains form?

Question 7

What is the difference between brittle and ductile rocks?

Question 8

What does tension stress result from?

Question 9

What does shear stress result from?

Question 10

Describe the plate tectonics processes and associated stresses that have led to the formation of the Himalayas,the world's largest mountain range?

Question 11

What does compression stress result from?

Question 12

What is meant when rocks are said to be deformed (fractured or folded)?

Question 13

What is the dip of an inclined layer of rock?

Question 14

How do geologists stabilize a slope for highway construction?

Question 15

What is the difference between faults and joints?

Question 16

If the mantle transmits S-waves,then how can it behave like a liquid,as implied by the principle of isostasy?

Question 17

What is the distinction between the hanging wall and the footwall of a fault?

Question 18

Briefly explain why,according to the principle of isostasy,continental crust should be thicker than oceanic crust.

Question 19

If the foci of most earthquakes lie at depths of less than 30 km,what does this indicate about the behavior of rocks in terms of brittle and ductile deformation?

Question 20

What is the difference between elastic and plastic deformation?

Question 21

Strike-slip faults are caused by ____________________ forces.

Question 22

A fault with both dip-slip and strike-slip movement is classified as a(n)____________________-____________________ fault.

Question 23

A(n)____________________ divides a fold into two halves.

Question 24

What are some of the ways in which terranes differ from surrounding strata?

Question 25

Sedimentary rocks that are now tilted were deposited ____________________.

Question 26

Each half of a fold is known as a(n)____________________.

Question 27

A simple bend or flexure,in an otherwise horizontal rock layer,is called a(n)____________________.

Question 28

Deformation caused by stress that exceeds a material's internal strength is known as ____________________.

Question 29

In a(n)____________________,the youngest rocks are in the center and the oldest are on the outside.In a(n)____________________,the oldest rocks are in the center and the youngest are on the outside.

Question 30

Force applied to a given area is known as ____________________.

Question 31

What are some geologic processes which accompany orogenesis at oceanic-oceanic plate boundaries?

Question 32

An episode of mountain building is known as a(n)____________________.

Question 33

The principle that Earth's crust is in floating equilibrium with the denser mantle below is known as ____________________.

Question 34

A circular or oval fold in which the strata are up-arched,and the marginal strata are ____________________ in age than that of the interior is known as a(n)____________________.

Question 35

If both limbs of a fold dip in the same direction,the fold is ____________________.

Question 36

The direction of a line formed by the intersection of a horizontal plane with the plane of a layer of rock is called ____________________.

Question 37

A fold is the result of ____________________ deformation.

Question 38

Small accreted lithospheric blocks of foreign origin that differ completely from the rocks in surrounding regions are called ____________________.

Question 39

The type of fold that traps most of the world's produced petroleum is a(n)____________________.

Question 40

In an anticline,the beds in its axial region are ____________________ in age than the beds of its limbs,and all strata dip ____________________ the axis.

Question 41

If you're standing on ice above a pond and you hear a crack,what should you do?

A) remain as motionless until the cracking stops
B) lie down on the ice to distribute your weight more broadly on the ice
C) run as fast as you can to shore
D) not worry because the ice will not break
E) prepare for a swim

Question 42

On a geologic map the number adjacent to the strike and dip symbol is

A) the strike angle.
B) the dip angle.
C) the strike direction.
D) the dip direction.

Question 43

Where is the thickest crust found?

A) beneath mountains
B) at the old stable portions of the continents
C) at the continental margins
D) at the old stable portions of the ocean basins
E) at the mid-oceanic ridge spreading centers

Question 44

What are uplifted blocks called?

A) tensional blocks
B) grabens
C) horsts
D) fault blocks
E) graves

Question 45

In a reverse fault,the ____.

A) hanging wall goes up relative to the footwall
B) hanging wall goes down relative to the footwall
C) hanging wall and footwall remain in the same position vertically
D) two sides of the fault slide past each other horizontally
E) two sides of the fault move away from each other

Question 46

Pretend that you are standing with one foot on either side of a strike-slip fault and the right block moves toward you.This can be called a(n)_______ strike slip fault.

A) left-lateral
B) right-lateral
C) dip-slip
D) thrust

Question 47

The San Andreas Fault is a ____ fault.

A) normal
B) reverse
C) thrust
D) strike slip
E) recumbent

Question 48

In what type of fault does the hanging wall move up relative to the footwall at an angle of less than 45 degrees?

A) normal
B) strike-slip
C) reverse
D) thrust

Question 49

Movement along the San Andreas is ____.

A) compressional
B) tensional
C) right lateral
D) left lateral
E) vertical

Question 50

Continents grow and evolve by addition of felsic and mafic crust; a process known as what?

A) addition
B) accretion
C) concretion
D) convergence
E) conformation

Question 51

When an isolated mountain range occurs in the interior of a continent,one may infer that the range formed by what?

A) the collision of two continental plates
B) compressive forces acting on the opposing margins of a single plate
C) the rifting of the continent
D) the growth of a volcanic arc
E) the collision of two continental plates AND the growth of a volcanic arc

Question 52

Which of the following have become terranes?

A) island arcs and ocean ridges
B) seamounts
C) fragments of other continents
D) island arcs, ocean ridges and seamounts
E) all of these

Question 53

Fracturing of rock can occur to depths as great as 900 km.

Question 54

The forces that produce block-faulted mountains,such as the Basin and Range Province of the Western United States,are

A) extensional
B) compressional
C) elastic
D) shear

Question 55

Dip-slip faults include ____.

A) normal faults
B) reverse faults
C) thrust faults
D) normal and reverse faults
E) All of these

Question 56

Rocks that are tilted were deposited ____.

A) on a slope in their present orientation
B) in an unknown orientation and then were tilted into their current position
C) horizontally and then were tilted into their current orientation
D) vertically and then were tilted into their current orientation
E) on the continental shelf and then uplifted

Question 57

The zone of rubble found along a fracture that has had movement on both sides is called

A) conglomerate.
B) angular unconformity.
C) fracture rubble.
D) fault breccia.

Question 58

Most folding of rocks occurs near the surface.

Question 59

The type of strain which occurs depends not only on the kind of stress applied,but also on what?

A) the amount of pressure and degree of temperature
B) the rock type
C) the duration of the stress
D) the amount of pressure, the degree of temperature and the duration of the stress
E) the amount of pressure, the degree of temperature and the rock type

Question 60

Volcanic island arcs are characteristic of which type of convergent plate boundaries?

A) continental-continental
B) continental-oceanic
C) oceanic-oceanic
D) continental-oceanic AND oceanic-oceanic
E) All of these

Question 61

Continental crust is always thicker than oceanic crust.

Question 62

The Andes formed as result of oceanic-continental convergence.

Question 63

Because movement along a strike-slip fault is just horizontal,quakes along these faults are small and do not do much damage.

Question 64

The most active orogenic belts today are the Alpine-Himalayan belt and the circum-Pacific belt.

Question 65

Most orogenesis takes place on oceanic-oceanic convergent plate boundaries.

Question 66

Divergent plate boundaries are responsible for most orogenesis.

Question 67

All mountains are made of continental crust.

Question 68

An important means of continental accretion is plutonism.