Chapter 8- Structural Geology

Question 1

bed

Answer 1

a unit of sedimentation which can vary in thickness

Question 2

bedding planes

Answer 2

mark the break between beds

Question 3

dip

Answer 3

maximum inclination of a bed measured from the horizontal using a clinometer

Question 4

true dip

Answer 4

the actual angle of dip measured at right angle to te strike

Question 5

strike

Answer 5

horizontal line on a bedding plane, measured as a bearing from north using a compass

Question 6

apparent dip

Answer 6

a dip that is measured to be less than the maximum

Question 7

true thickness

Answer 7

thickness of the bed measured at right angle to the bedding planes

Question 8

apparent thickness

Answer 8

thickness of the bed measured as seen at the outcrop but not at right angle to the bedding plane

Question 9

fault

Answer 9

fracture in a rock along which there had been an observable displacement

Question 10

fault plane

Answer 10

plane of fracture along which the rocks have been displaced

Question 11

upthrow

Answer 11

side of the fault where the movement is upwards, relative to the other

Question 12

downthrow

Answer 12

side of the fault where movement is downward in relation to the other side

Question 13

throw

Answer 13

vertical displacement of rocks along a fault plane

Question 14

footwall

Answer 14

the side of the fault that lies below the fault plane, if the fault is not vertical

Question 15

hanging wall

Answer 15

side of the fault that lies above the maximum inclination of the fault plane as measured from the horizontal

Question 16

dip-slip fault

Answer 16

movement along the fault plane is parallel to the dip of the fault plane

Question 17

normal faults

Answer 17

the hanging wall is the downthrow side

Question 18

horst and graben

Answer 18

series of normal faults
horst is elevated, graben is dropped

Question 19

reverse faults

Answer 19

formed by compressional forces
hanging wall is the upthrow side

Question 20

thrust fault

Answer 20

type of reverse fault where the fault dip is less than 45

Question 21

strike slip fault

Answer 21

faults where the fault plane is vertical or near vertical and movement along the fault plane is horizontal

Question 22

tear fault

Answer 22

result of shearing forces applied to rocks

Question 23

slickensides

Answer 23

striations and polishing found on a fault plane indicative of relative movement

Question 24

fault breccia

Answer 24

composed of fragments produced by rocks fracturing during faulting, found along fault planes

Question 25

fault gorge

Answer 25

composed of very finely ground particles produced by grinding of rock during faulting. fused together by heat

Question 26

mylonite

Answer 26

rock produced by dynamic recrystalisation of crystals on a fault plane

Question 27

anticline

Answer 27

upright fold with oldest rocks int he core

Question 28

antiform

Answer 28

upward closing fold

Question 29

syncline

Answer 29

downward pointing fold with the youngest rocks in the core

Question 30

synform

Answer 30

a downward closing fold

Question 31

fold limb

Answer 31

section of a fold between one hinge and the next

Question 32

hinge

Answer 32

line along which there in a change in the direction of/amount of dip

Question 33

crest

Answer 33

highest point of a folded bed

Question 34

trough

Answer 34

lowest point of a folded bed

Question 35

axial plane

Answer 35

plane that joins the hinges of all the beds. bisects the fold

Question 36

axial plane trace