Geological Structures

Question 1

What is structural geology

Answer 1

Study of rock formation

Question 2

What is another name for mountain building

Answer 2

orogenesis

Question 3

What are the two terms used to describe different orientations of a flat surface

Answer 3

Strike and Dip

Question 4

What does strike mean

Answer 4

the compass direction of the line of intersection on the dipping flat surface of INCLINED PLANES

Question 5

What is dip

Answer 5

The angle between a horizontal plane and the inclined plane

Question 6

What angle is the dip measured at

Answer 6

Measured perpendicular to direction of strike

Question 7

What symbol is used to indicate the direction of the slip

Answer 7

a strait line parallel to the compass direction

Question 8

What symbol is used to indicate the dip angle

Answer 8

a short tick mark with the angle next to it

Question 9

what is the definition of stress

Answer 9

the force which causes strain

Question 10

what are the types of stress

Answer 10

compression, extension, shear

Question 11

what is shear stress

Answer 11

blocks of rocks SLIDING PAST each other

Question 12

What are characteristics of compression

Answer 12

thickening material, found at convergent

Question 13

what are characteristics of extension

Answer 13

thinning material, found at divergent boundaries

Question 14

what are characteristics of shear stress

Answer 14

rocks neither thickened or thinned but some shape change, found at transform boundaries

Question 15

what is the definition of strain

Answer 15

how a material reacts when stress is applied

Question 16

what are key differences between stress and strain

Answer 16

stress is force applied and strain is the resulting deformation

Question 17

what is displacement

Answer 17

change in location

Question 18

what is rotation

Answer 18

change is orientation

Question 19

what is distortion

Answer 19

change in shape

Question 20

what are the two types of deformation types

Answer 20

brittle and ductile

Question 21

what does brittle deformation show as

Answer 21

creates cracks

Question 22

what does ductile deformation show as

Answer 22

creates folds

Question 23

where does brittle deformation occur

Answer 23

closer to earths surface where temp is COOLER. COLD=BRITTLE

Question 24

where does ductile deformation occur

Answer 24

deeper in the crust where temps are hotter and FLOW better

Question 25

What is the other component of deformation types

Answer 25

strain rate. faster force means more likely breakage not flow

Question 26

What are joints

Answer 26

fractures that have had no movement or shifting

Question 27

What are characteristics of joints

Answer 27

- can be described by strike and dip - typically in parallel strips - result from tensional tectonic stress - pathways for water and thus chemical weathering

Question 28

What are faults

Answer 28

planar fractures where rock has been offset or shifted

Question 29

What are characteristics of faults

Answer 29

- abundant and have variety of scales - can be active or inactive - vary by type of stress

Question 30

what is a dipping fault

Answer 30

fault that is not straight up and down

Question 31

What is the block above the fault called

Answer 31

hanging wall

Question 32

what is the block below the fault called

Answer 32

footwall

Question 33

What is a dip slip fault

Answer 33

when the fault plane is angled and the movement is parallel to the dip

Question 34

What are the types of dip slip faults

Answer 34

normal, reverse, and thrust

Question 35

What is the orientation of a normal fault

Answer 35

the hanging wall moves down relative to the foot wall

Question 36

what causes normal faults

Answer 36

crustal extension (pulling apart)

Question 37

What is the orientation of reverse and thrust faults

Answer 37

hanging wall moves up relative to the footwall

Question 38

What causes reverse and thrust faults

Answer 38

crustal shortening (compressive stress)

Question 39

What determines a fault as reverse or thrust

Answer 39

how steep/shallow the fault is dipping

Question 40

What angle makes a fault reverse

Answer 40

steeper than 35

Question 41

what angle makes a fault thrust

Answer 41

less than 35

Question 42

What is a strike slip fault

Answer 42

fault motion parallel to strike of the fault (back and forth not up and down)

Question 43

What determines a left or right lateral fault

Answer 43

the block opposite of where the observer is standing moves to either right or left side

Question 44

What is oblique slip

Answer 44

combo of dip and strike slip motion

Question 45

what is a hinge line

Answer 45

pint of max curvature along the fold

Question 46

what is the hinge line/fold axsis

Answer 46

line connecting all the hinge points

Question 47

what is a limb

Answer 47

less curved sides of a fold

Question 48

what is an anticline

Answer 48

arch like or A shaped fold LIMBS DIP AWAY FROM HINGE

Question 49

what is a syncline

Answer 49

U shaped fold LIMBS DIP TOWARD HINGE

Question 50

what are flexural folds

Answer 50

layers that slip as stratified rocks are bent formed from compressional stress on either side

Question 51

what are flow folds

Answer 51

non-uniform folds formed by ductile flow of hot soft rock

Question 52

what rocks commonly have flow folds

Answer 52

igneous or metamorphic rocks

Question 53

what is a plunging fold

Answer 53

a fold axis that is tilted or not level with ground surface

Question 54

what is a non plunging fold

Answer 54

a horizontal fold axis level with the ground surface

Question 55

what is dome

Answer 55

a fold that looks like an overturned bowl where layers dip away from center