The Solid Earth - Chapter 8: Rock Deformation

Question 1

What are two common ways rocks might deform?

Answer 1

folding

fracturing

Question 2

When do rocks begin to deform?

Answer 2

When rocks are subjected to stresses greater than their own strength

Question 3

When stress is applied, rocks respond by deforming ______

Answer 3

elastically

Question 4

True or false: changes resulting from elastic deformation are reversible

Answer 4

True

Question 5

When might rocks return to nearly original size and shape?

Answer 5

When stress is removed

Question 6

What results when the elastic limit surpassed as rocks are deformed?

Answer 6

Plastic deformation or fracture

Question 7

This results in permanent change, that is, the size and shape of a rock unit are altered through the folding and flowing

Answer 7

Plastic deformation

Question 8

If stress is applied quickly, rocks tend to ___

Answer 8

fracture

Question 9

During mountain building, flat lying sedimentary and volcanic rocks are often bent into a series of undulations called -

Answer 9

folds

Question 10

Two most common forms of folds

Answer 10

anticline

syncline

Question 11

This type of fold is most commonly formed by the upfolding, or arching, or rock layers. They are sometimes spectacularly displayed where highways have been cut through deformed strata

Answer 11

Anticline

Question 12

This type of fold is a downfold or trough

Answer 12

syncline

Question 13

Three adjectives to differentiate anticline and synclines

Answer 13

symmetrical
asymmetrical
overturned

Question 14

Folds don’t continue forever but die out at the end. The folds are said to be _____ since the axis of the fold is going into the ground

Answer 14

plunging

Question 15

Most folds are caused by compressional stresses, but are caused by ____ displacement

Answer 15

vertical

Question 16

When unwarping produces a circular or somewhat elongated structure

Answer 16

Dome

Question 17

Downwarped structures that have a similar shape to domes

Answer 17

basins

Question 18

Fractures in the crust along with appreciable displacement has occurred

Answer 18

faults

Question 19

Faults in which the movement is primarily vertical

Answer 19

dip slip faults

Question 20

the rock immediately above the fault surface

Answer 20

hanging wall

Question 21

the rock below the fault surface

Answer 21

foot wall

Question 22

Dip slip faults are called ____ when the hanging wall moves down relative to the footwall

Answer 22

normal fault

Question 23

These faults occur when the hanging wall moves up relative to the footwall

Answer 23

reverse

Question 24

Reverse faults that have a low angle are called -

Answer 24

thrust faults

Question 25

These faults happen when the dominant displacement is along the trend or strike of the fault

Answer 25

strike slip

Question 26

When faults have both vertical and horizonal movement

Answer 26

oblique slip faults

Question 27

Normal faults indicate the existence of _____ stresses that pull the crust apart

Answer 27

tensional

Question 28

A central block that is bounded by normal faults and drops as the plates separates

Answer 28

graben

Question 29

These grabens produce an elongated valley bounded by upfaulted structures called…

Answer 29

horsts

Question 30

Since the blocks involved in reverse and thrust faulting are displaced toward one another, geologists conclude that ____ forces are at work

Answer 30

compressional

Question 31

Fractures along which no appreciable displacement has occurred

Answer 31

joints