Rock Structure and Landforms

Question 1

What is rock structure?

Answer 1

Rock structure is the arrangement of rocks brought about by folding and faulting.

Question 2

What are tectonic forces?

Answer 2

Tectonic forces continuously deform the rocks of the lithosphere by squeezing, stretching, bending and breaking them.

Question 3

Name the 3 different types of force involved in rock deformation.

Answer 3

Compression
Tension
Shearing

Question 4

What is compression?

Answer 4

Compression squeezes and shortens a body of rock. It may result in folding and/or faulting.

Question 5

What is tension?

Answer 5

Tension lengthens a body of rock. It results in faulting in the rock.

Question 6

What is shearing?

Answer 6

Shearing deforms a rock body so that one side is forced to slide past the other. It results in faulting in the rock.

Question 7

What are the 4 different types of fold?

Answer 7

Simple fold
Asymmetrical fold
Overfold
Overthrust fold

Question 8

What is a simple fold?

Answer 8

Both of the limbs of the anticline have the same degree of slope.

Question 9

What is an asymmetrical fold?

Answer 9

The slope of one limb of the anticline is greater than the slope of the other limb.

Question 10

What is an overfold?

Answer 10

The strata in one limb have been tilted beyond the vertical. The order of some strata has been reversed, with older strata lying on younger strata.

Question 11

What is an overthrust fold?

Answer 11

The rock has sheared and one limb is pushed forward over the other so that the rock strata are no longer continuous.

Question 12

What are the 3 main parts of a fold?

Answer 12

Anticline - upfold or arch
Syncline - downfold or trough
Limb - two arms of the fold

Question 13

Name 3 major periods of fold mountain building.

Answer 13

Caledonian (old fold mountains)
Armorican ( old fold mountains)
Alpine (young fold mountains)

Question 14

What is orogeny?

Answer 14

Orgeny is a major period of fold mountain formation, during which orogenesis (mountain building) occurs.

Question 15

What causes faulting?

Answer 15

Faulting is caused by the forces of compression, tension and shearing.

Question 16

What are the 3 main types of faults?

Answer 16

Normal faults
Reverse faults
Tear faults

Question 17

What is a normal fault?

Answer 17

A normal fault is usually the result of tension stresses that tend to pull plates apart. The movement is mainly vertical, where one slips down past another.

Question 18

What is a reverse fault?

Answer 18

A reverse fault is the result of compression. The movement is vertical, but one block is forced up relative to the other.

Question 19

What is a tear fault?

Answer 19

A tear fault is a vertical fracture in the rock where one block shifts sideways (horizontally) relative to the other.

Question 20

In relation to faulted structures, what is scarp?

Answer 20

The term scarps (short for escarpment) refers to the cliff formed directly by the vertical displacement of rock strata.

Question 21

In relation to faulted structures, what is throw?

Answer 21

Throw refers to the degree of vertical displacement of rock strata on either side of a fault.

Question 22

In relation to faulted structures, what is heave?

Answer 22

Heave refers to the horizontal displacement of the strata.

Question 23

How are block mountains formed?

Answer 23

When two or more faults occur in the same area, large blocks of crustal rock may be uplifted to form a block mountain.

Question 24

How are rift valley formed?

Answer 24

When two are more faults occur in the same area, large blocks of crustal rock may drop down between them to form a rift valley.