Chapter 10: Crustal Deformation and Mountain Building

Question 1

What is crustal deformation and what occurs?

Answer 1

All changes in the original form and/or size of a rock body.
Most crustal deformation occurs along plate margins.
(deformation may occur when stress is applied)

Question 2

Factors that influence rock strength

Answer 2

1. Temperature and confiding pressure that the rock is experiencing
2. Rock type: Igneous, Sedimentary, and Metamorphic
3. Time involved for deformation

Question 3

A Crustal Deformation can be what?

Answer 3

Elastic- these are recoverable (elastic rebound theory)
Brittle- exhibit brittle failure once strength is surpassed
Ductile- solid state flow that produces a change in shape of rocks without fracturing

Question 4

What is a rock fold?

Answer 4

Rocks bent into a series of waves

Question 5

What are the two types of rock folds?

Answer 5

Anticline- unfolded, or arched, rock layers (looks like an ‘A’ or a rainbow)
Syncline- downfolded rock layers (looks like a ‘U’ or a ‘V’)

Question 6

The rocks crust shortens and thickens due to what type of folded stress?

Answer 6

Compressional stress!

Question 7

Anticlines and Synclines can be what?

Answer 7

1) Symmetrical- limbs are mirror images (boomerang)
2) Asymmetrical- limbs are NOT mirror images (check mark)
3) Overturned- one limb is tilted beyond vertical (one limb underneath another limb)

Question 8

What does D.A.M.O statdnd for?

Answer 8

Domes
Anticlines
Middle is
Oldest

Question 9

What is a dome fold?

Answer 9

-Circular, slightly elongated
-Upwarped displacement of rocks
-OLDEST rocks are in center of dome; exposed through weather/erosion
EX: Black Hills, South Dakota

Question 10

What is a basin fold?

Answer 10

-Circular, slightly elongated
-Downwarped displacement of rocks
-YOUNGEST rocks are found in the center of the basin
EX: Bedrock geology of Michigan

Question 11

Types of Faults

Answer 11

1) Dip-Slip faults

2) Strike-Slip fault

Question 12

What is a Dip-Slip fault and its components?

Answer 12

The movement along the inclination (dip) of fault plane

Hanging wall- rock above fault surface
Footwall- rock below fault surface

Question 13

Two types of Dip-Slip faults

Answer 13

1) Normal faults-
hanging wall block moves down.
Caused down by tensional forces

2) Reverse & Thrust faults-
hanging wall block moves up relative to the footwall
Caused by strong compressional stresses
—->

Question 14

What is a Strike-Slip fault and its one type

Answer 14

Dominant displacement is horizontal and parallel to the trend, or strike of the fault

Transform fault-
Large strike-slip fault cuts through lithosphere
Often associated with plate boundaries

Question 15

A type of rock structure that is associated with faults?

Answer 15

Joints- Fractures in the rock along which NO displacement (offset) has occurred.

NOT A FAULT; a crack or break in the rock due to strain

Question 16

The process that collectively produce a mountain belt

Answer 16

Orogenesis

orogeny or mnt. building occurs at convergent boundaries

Question 17

Three types of Mountain Building at Convergent boundaries

Answer 17

1) Andean-Type Mnt. Building
2) Continental- Continental Collision
3) Continental Accretion

Question 18

What is a Continental - Continental Collision?

Answer 18

2 plates w/ continental crust converge and push up because neither plate is dense enough to be subducted
EX: Himalayan mountains

Question 19

What is Continental Accretion?

Answer 19

Small crustal fragments collide w/ and are joined to continental margins
Occurred along the Pacific W. Coast

Question 20

Buoyancy is the principle for what?

Answer 20

Isostasy

Question 21

What is the process of isostatic adjustment?

Answer 21

The weight is removed from the crust, crustal uplifting occurs.
(the concept of floating crust that is in gravitational balance.)

Question 22

Accreted crustal blocks are called?

Answer 22

Terranes