Module 7

Question 1

why do rocks fold and fault

Answer 1

rocks are subject to stress (force per unit area) and undergo strain in response,

Question 2

compressional stress

Answer 2

forces pushing together

Question 3

what is an example of compressional stress

Answer 3

C-C, O-C, and O-O convergent plate margins

Question 4

tensional stress

Answer 4

forces pulling apart

Question 5

what is an example of tensional stress

Answer 5

divergent plate margins

Question 6

shear stress

Answer 6

parallel, opposing forces

Question 7

what is an example of shear stress

Answer 7

transform plate margins

Question 8

how do rocks respond to stress on a large scale?

Answer 8

in one of three ways: elastic, plastic, or brittle

Question 9

elastic response

Answer 9

deformed body recovers when stress is removed.

Question 10

what happens when the stress applied to rock goes beyond its elastic limit

Answer 10

there is permanent deformation, and it can be considered a plastic response

Question 11

plastic response

Answer 11

rock bends but does not return to its original shape. high temp and pressure lead to plastic behaviour

Question 12

examples of plastic response rocks

Answer 12

glacial ice and asthenosphere

Question 13

brittle response

Answer 13

rock breaks or fractures very easily

Question 14

examples of brittle response

Answer 14

surface rocks, and faults

Question 15

anticline

Answer 15

upward arching fold

Question 16

syncline

Answer 16

downward arching fold

Question 17

what can be said about anticline and syncline folds

Answer 17

often happen together, and the hinge lines are about 90 degrees

Question 18

hinge line

Answer 18

axis of the fold

Question 19

axial plane

Answer 19

plane containing all hinge lines of a fold

Question 20

types of folds

Answer 20

anticline, syncline, monocline, recumbent fold, thrust folds, and overturned folds

Question 21

overturned folds

Answer 21

anticline axial plane goes over the syncline axial plane

Question 22

recumbent folds

Answer 22

axial planes of anticline and syncline are orientated parallel to horizon

Question 23

example of folds

Answer 23

Appalachian valley and ridge

Question 24

types of fractures in rocks

Answer 24

joints and faults

Question 25

joints

Answer 25

rock fractures with no displacement, and is usually on a smaller scale

Question 26

what is a fracture

Answer 26

a break in response to stress

Question 27

what is a fault

Answer 27

a rock fracture where movement has taken place

Question 28

active fault

Answer 28

movement within the last 11,000 years

Question 29

hanging wall block

Answer 29

overlies an inclined fault plane

Question 30

footwall block

Answer 30

underlies an inclines fault plane

Question 31

normal fault

Answer 31

hanging wall block moves downward relative to the footwall block. can produce a graben or a horst

Question 32

example of normal fault

Answer 32

rift valleys

Question 33

reverse fault

Answer 33

hanging wall block moves upwards relative to the footwall

Question 34

what stress/boundary causes a reverse fault

Answer 34

compressional stress/convergent boundary

Question 35

what stress/boundary causes a normal fault

Answer 35

tensional stress/divergent boundary

Question 36

horst

Answer 36

a block is pushed upwards relative to the blocks on either side by the faulting

Question 37

graben

Answer 37

a block that has been lowered relative to the blocks on either side due to the faulting

Question 38

thrust fault

Answer 38

reverse fault with very low angle fault plain (<45 degrees)

Question 39

strike-slip fault

Answer 39

a fault where the movement is predominantly horizontal and therefore parallel to the strike of the fault

Question 40

what type of stress/boundary causes a strike-slip fault

Answer 40

shear stress/transform boundaries

Question 41

what is needed for fossil fuels to form

Answer 41

carbon-based life, heat, and pressure

Question 42

where may we find water/oil/gas

Answer 42

anticlines and faults

Question 43

stress

Answer 43

force per unit area

Question 44

folds

Answer 44

bends in layered rock; plastic strain

Question 45

strain

Answer 45

a change in size/shape as a response to stress