STRUCTURES

Question 1

types of stress

Answer 1

compression, tension, shear.
causes: * Tectonic forces, gravity, and the pressure form overlying rocks

Question 2

compression

Answer 2

shortening
folding, reverse fault

Question 3

tension

Answer 3

stretching
thinning crust
normal fault

Question 4

shear

Answer 4

parallel forces, on opposite side of a plane [twisting laterally]
* Bending horizontally, strike-slip fault

Question 5

o Strain (deformation): change in shape or size due to stress. Observed in a material (rocks) is a function of

Answer 5

 Types of stress
 How stress is applied
 Temperature
 Material properties
 Speed at which stress is applied

 Strain is how rocks respond to stress, expressed in rocks by: folding (bending), or faulting (breaking)

Question 6

• Distinguish between the 3 types of deformation

Answer 6

elastic, plastic, brittle

Question 7

 Elastic deformation

Answer 7

• Temporary change in shape or size
• Recovers when stress is removed
• Stores energy

Question 8

 Plastic deformation

Answer 8

• Permanent change in shape or size- results in folding

Question 9

 Brittle deformation

Answer 9

• Loss of cohesion due to stress
• In ricks results in faults and fractures

Question 10

o Syncline:

Answer 10

strata slope upward away from the axis of folding

Question 11

o Anticline :

Answer 11

strata slop downward away from the axis
 These can create domes and basins

Question 12

the hinge

Answer 12

is the horizontal line that defines the part of the fold with he sharpest curve

Question 13

folded landscapes

Answer 13

o A synclinal ridge is formed when the differing composition of strata resulting in different weathering responses

Question 14

o Faulting:

Answer 14

occurs when rocks on either side of the fracture shift relative to the other side. Fault zones are areas where fractures in the rock demonstrate crustal movement

Question 15

o Folding vs faulting

Answer 15

 Fold- strain involves plastic deformation to accommodate for stress
 Fault- strain involves brittle failure to accommodate stress

Question 16

o Normal

Answer 16

 Tension
 One side slips up (footwall) and one slides down (hanging wall)
 A fault scarp identifies the displacement of the ground

Question 17

reverse

Answer 17

 Compression
 Hanging wall moves up relative to the footwall
 Thrusts low angle reverse faults – can result in overthrusting (old rock lying nearly horizontal with young)

Question 18

o Strike-slip

Answer 18

 Shear stress
 Side to side movement
 Transform fault – san andreas fault

Question 19

o Faulted landscapes produce

Answer 19

 Horst: upward faulted block
 Graben: downward faulted block
 Normal faulting - extension

Question 20

o Crustal formation

Answer 20

 Magma less dense = rise

Question 21

o Three uplift crustal regions

Answer 21

 Tectonic mountains and landforms – produced by foding, faulting, and crustal movement
 Volcanic feature, formed by surface accumulation of molten rock from eruptions of subsurface materials
 Residual mountains and stable continental cratons, formed from inactive remnant of ancient tectonic activity

Question 22

o Craton

Answer 22

 Craton: Old stable part of continental crust
* Compatible with diamonds
 Continental shield- region w/ craton that is exposed
* Untouched by tectonic process, away from boundaries
 Platform: continental area covered by relatively flat or gently tilted sedimentary strata
 Basement/ crystalline basement- region below sedimentary platform/cover

Question 23

• Understand how mountains are built

Answer 23

volcanic eruptions, uplift and erosion compression of plates/ thrust faults, crustal extension

Question 24

 Volcanic eruption

Answer 24

• Lava piles up, convergent margins, hot spots, divergent margins (most under the sea)

Question 25

 Uplift (and erosion)

Answer 25

• Floating lithosphere is subject to gravitational forces and buoyancy
• Occurs due to the internal heat and thickness of the root

Question 26

 Compression of plates/ thrust falls

Answer 26

• Regional compression over large areas
• Orogeny at convergent margins
  o Oceanic plate- continental plate collision orogenesis
  o Oceanic plate- oceanic plate collision orogenesis
  o Continental plate- continental plate collision orogenèses

Question 27

 Crustal extension

Answer 27

• Basin and range extension – thins crusts but also makes local topographic high

Question 28

o Oceanic- continental example

Answer 28

Andes mountains (south America)

Question 29

continental- continental example

Answer 29

Himalayan mountains

Question 30

• Explain how accretion of terranes are related to the geological history of BC

Answer 30

o Accretion of terranes
 Continents can be extended through the process of adding terrains as volcanic island arcs
 BC is a result of accretion of material like micro continents and islnd arcs being added to the west coast