Surface and Internal Processes of the Rock Cycle

Question 1

Why do plate tectonic happen?

Answer 1

Rocks are put under stress

Question 2

What stresses can rocks be put under?

Answer 2

Compression
Tension

Question 3

What is stress?

Answer 3

The force applied to the rock

Question 4

What is strain?
Give examples of strains

Answer 4

The way in which the rock reacts

Strain could be:
- snapping (fault)
- bending (fold)
- thinning (tension)
- thickening (compression)

Question 5

Give the rock structures formed due to strain

Answer 5

Dipping
Folding
Faulting

Question 6

What is dipping?

Answer 6

The plane orientation as the rocks all tilt one way

Question 7

During dipping, which layer of rock is youngest and why?

Answer 7

The rock at the surface
- principle of superposition

Question 8

What are the two types of fold?

Answer 8

Synform
Antiform

Question 9

What do we call folds if they are the right way up?

Answer 9

Syncline
Anticline

Question 10

What is the synform shape?

Answer 10

The sink, like a basin, U

Question 11

What is the shape of an antiform?

Answer 11

Broken A, upside down U, n

Question 12

Where are the rock ages in a syncline or anticline?

Answer 12

Syncline: youngest in the middle, oldest on the bottom

Anticline: oldest in the middle, youngest on the top

Question 13

What do you call a fold that is the wrong way round but you know how old the rocks are?

Answer 13

Synformal anticline
Antiformal syncline

Question 14

What are the features of a fold?

Answer 14

Hinge
Axial plane
APT
Interlimb angle
Fold axis
Limbs

Question 15

What is the hinge of a fold?

Answer 15

Point where two limbs meet

Question 16

What is the interlimb angle in a fold?

Answer 16

The angle between the limbs

Question 17

What is the APT in a fold?

Answer 17

The point where the axial plane meets the fold

Question 18

What are the names for the different angles in a fold?

Answer 18

> 70° = open
<70° = tight
Parallel limbs = isoclinal

Question 19

What are the different attitudes of a fold axis?

Answer 19

Upright
Inclined
Overturned
Recumbent

Question 20

What is competance?

Answer 20

The mechanical strength of a rock

Question 21

What are the characteristics of competent rocks?
Give examples

Answer 21

RESISTS:
- erosion
- deformation
- folding
- faulting

E.G.
Metamorphic
Igneous
Limestone
Sandstone

Question 22

Give the characteristics of incompetent rocks
Give examples

Answer 22

EASILY:
- deforms
- erodes

E.G.
Mudstone
Shale

Question 23

What factors affect the way a rock responds to stress?

Answer 23

Competence of rock
Temperature
Speed

Question 24

How does competence of rock affect the way in which a rock responds to stress?

Answer 24

COMPETENT = brittle and more likely to fault

INCOMPETENT = behaves more plastic more likely to fold

Question 25

How does temperature affect the way in which a rock responds to stress?

Answer 25

HOTTER = more likely to behave plastically and fold

Question 26

How does speed of stress applied affect the way in which a rock responds to stress?

Answer 26

FAST = more likely to fault

Question 27

What is faulting?

Answer 27

Cracks in rocks along which movement has taken place

Question 28

What are the two different types of fault?

Answer 28

Strike slip point Dip slip

Question 29

What is a strike slip point?

Answer 29

Rocks moving sideways along the fault

Question 30

What directions can strike slip points move?

Answer 30

Dextral - moving right Sinistral - moving left

Question 31

What is a dip slip fault?

Answer 31

When the rocks move up and down relative to each other

Question 32

How do we measure dip slip?

Answer 32

Throw and heave and angle of fault plane

Question 33

What is throw? What is heave?

Answer 33

Throw = vertical displacement Heave = horizontal displacement

Question 34

What are the 3 components in a dip slip fault?

Answer 34

Hanging wall Foot wall Marker bed

Question 35

What is the foot wall?

Answer 35

The one on the bottom of a dip slip, the one you could theoretically stand on

Question 36

What is the hanging wall?

Answer 36

The top one in a dip slip, you can't theoretically stand on it

Question 37

What are the two types of movement at a dip slip fault?

Answer 37

NORMAL - hanging wall goes down REVERSE - hanging wall goes up

Question 38

What is it called if the angle of fault plane in a dip slip is 45° or less?

Answer 38

THRUST - always a reverse movement

Question 39

What is the 'map' of an area?

Answer 39

view from above

Question 40

What is the cross section of an area?

Answer 40

The view from the side if you sliced it open

Question 41

What direction does the rock dip?

Answer 41

towards the youngest rock, so the one on the top

Question 42

How do you draw a dip?

Answer 42

Line with a triangle pointing the direction of the dip

Question 43

What is the line in the dipping symbol?

Answer 43

Strike

Question 44

What is strike in a dipping symbol?

Answer 44

orientation at right angles to the dip

Question 45

What is dip in a dipping symbol?

Answer 45

The direction the rocks are dipping

Question 46

How would you describe a strike?

Answer 46

2 opposing compass points e.g. east-west

Question 47

How would you describe a dip?

Answer 47

1 compass point e.g. south

Question 48

What is an unconformity?

Answer 48

a boundary between 2 rock units which mark a gap in deposition

Question 49

Describe an example of an unconformity forming

Answer 49

1. original rocks laid down horizontally 2. tectonic processes lead to faulting 3. erosion wears away the surface 4. a new period of deposition starts. The unconformity is the line between the two where it seems that two one type changes immediately into the next