FOLDS AND FAULTS

Question 1

What is the difference between stress and strain?

Answer 1

• Stress is the force applied over an area

- strain is the change or distortion produced by a stress

Question 2

Stress that acts equaly from all directions is-

if it is not equal it is-

Answer 2

Uniform

Diferential

Question 3

Tensional stress-
Compressional stress-
shear stress-

Answer 3

• streches rock
• compresses rock
• results in slippage and destortion

Question 4

What is elastic deformation?

Answer 4

when the rock returns to it’s original shape when the stress is removed

Question 5

What is the yield point or elastic limit?

Answer 5

The maximum stress a given rock can withstand without becoming permanently deformed. showing plastic or ductile behavior

Question 6

Describe a brittle maerial

Answer 6

have a small or large region of elastic

behaviour but only a small region of ductile behaviour before they fracture.

Question 7

describe a ductile material

Answer 7

have a small region of elastic

behaviour and a large region of ductile behaviour before they fracture.

Question 8

Name 5 factors that effect the brittle/ductile nature of the rock

Answer 8

• time
• tempreture
• confining pressure
• composition
• presence of water

Question 9

wich minerals are 1) brittle and 2) ductile?

Answer 9

1) quartz, olivene, f’spar

2) caly, mica, calcite

Question 10

define 1)competent and 2) incompetent rocks

Answer 10

rocks that only deform under 1) great stress 2) moderate to low stress

Question 11

describe a dip slip fault

Answer 11

Dip slip faults are faults that have an inclined fault plane and
along which the relative displacement or offset has occurred
along the dip direction.

Question 12

describe a strike slip fault

Answer 12

Here the fault surface is usually near vertical and the footwall
moves either left or right or laterally with very small vertical
motion.

Question 13

what is a thrust fault?

Answer 13

low angle reverse fault

Question 14

what is a slickenside?

Answer 14

parralel sirations on rock face produced by relative motion alog fault planes

Question 15

what is fault gouge?

Answer 15

debri produced by the crushing and grinding of rough rock surfaces on each side of a fault

Question 16

what is fault breccia?

Answer 16

Fragmented rock in which angular fragments were formed by brittle fault movement; fault breccia occurs along a fault.

Question 17

what is mylonite?

Answer 17

a cleavegeless rock with a strecky banded structure.
produced by the extreme
granulation and shearing of rocks that have
been pulverized and rolled during
overthrusting or intense dynamic
metamorphism.
MICCROBRECCIA WITH FLOW TEXTURE

Question 18

Where is the 1) hinge and 2) limb of a fold?

Answer 18

1) the place where the rocks are bent

2) the two sides

Question 19

what is the axial plane? and what is ‘axial plane trace’

Answer 19

the line that bisects the angle of the fold.

it’s trace is where it intersects the earth’s surface

Question 20

what is the 1)wavelength and 2) amplitude of a fold

Answer 20

1) the distance between two crests/ troughs

2) half the vertical distance between the crecst and trough of a fold

Question 21

What are 1) upfolds and 2) downfolds called?

Answer 21

1) antiforms 2) synforms

Question 22

state the angle of a 
-gentle
-open
-closed
-tight 
-issoclinal
fold

Answer 22

• 120-180
• 70-120
• 30-70
• 0-30
• 0