Plate Boundaries & More

Question 1

What are plates driven by?

Answer 1

Plates are driven by cooling Earth in a heat transfer process called convection

Question 2

What provides additional force to move plates?

Answer 2

Gravity

Question 3

Plates moves due to:

Answer 3

• Differences in density

- Convection currents

Question 4

Convection currents:

Answer 4

• Warm material rises form inside the Earth to the surface. then cools and sinks
• As it does this, it pulls the overlying plate with it in the direction the current is moving

Question 5

How fast are the plates moving every year?

Answer 5

1-10 centimeters per year

Question 6

What are the tectonic plates (lithospheric plate)?

Answer 6

• The 100 km thick surface of the Earth
• Contains crust and part of the upper mantle
• It is rigid and brittle

Question 7

What is the asthenosphere?

Answer 7

• The hotter upper mantle below lithospheric plate

- Can flow like silly putty, but is a SOLID

Question 8

The three types of boundaries:

Answer 8

• Divergent
• Convergent
• Transform

Question 9

Divergent plate boundary:

Answer 9

• Plates are moving away from one another
• This occurs on the ocean floor along the mid-ocean ridges
• Lava moves out of the rift valley along the mid-ocean ridges

Question 10

How do divergent boundaries affect crust?

Answer 10

New crust is generated as the plates pull apart

Question 11

Where do divergent boundaries occur?

Answer 11

Ocean floors and continental interiors

Question 12

Earthquakes on divergent boundaries are?

Answer 12

shallow and small

Question 13

Two types of ridges?

Answer 13

Fast-spreading and slow-spreading

Question 14

Convergent plate motion:

Answer 14

• Two plates move toward each other
• Can be ocean to ocean, ocean to continent or continent to continent
• Oceanic crust is more dense, so it always sinks under or subducts

Question 15

Two continental plates crunch together and form?

Answer 15

high mountains

Question 16

Convergent- ocean to ocean features & example:

Answer 16

Island arc & trenches, ex: Marianas

Question 17

Convergent- ocean to continent features & example:

Answer 17

Mountains & trench, ex: Cascades

Question 18

Convergent- continent to continent features & example:

Answer 18

Folded mountains, ex: Himalayas

Question 19

Convergent boundary earthquakes:

Answer 19

Shallow, intermediate and deep

Question 20

Shallow convergent earthquakes:

Answer 20

The most destructive of these occur between the plates on the plate boundary

Question 21

Intermediate and deep:

Answer 21

Occur only within the subducting oceanic lithosphere

Question 22

Transform plate boundary:

Answer 22

• Plates slide past one another
• This occurs along a fault (crack in earth’s crust)
• Transform faults can be found along the mid-ocean ridge

Question 23

How is the lithosphere affected by transform plate boundaries?

Answer 23

It is neither produced nor destroyed as the plates slide horizontally past each other

Question 24

Two different types of faults and examples:

Answer 24

• Strike-slip fault, example: San Andreas fault

- Transform fault: a strike-slip fault between two spreading ridges allows the two plates to move apart

Question 25

Types of stress:

Answer 25

• Extension
• Compression
• Shear

Question 26

Extension:

Answer 26

Faults and regional thinning

Example: Basin & Range

Question 27

Compression:

Answer 27

Makes faults and folds

Example: Andes Mountains

Question 28

Shearing:

Answer 28

Displaces layers horizontally and can result in strike-slip faulting
Example: San Andreas fault

Question 29

Types of faults & examples:

Answer 29

• Normal, ex: basic & range african rift
• Reverse, ex: himalayas & rocky mountains
• Strike-Slip, ex: san andreas