1.b) Plate boundaries

Question 1

What are the four types of plate boundaries?

Answer 1

• constructive
• Destructive – subduction
• Destructive –collisional
• Conservative

Question 2

Explain characteristics of constructive plate margins

Answer 2

Plates are moving away from each other and then new crust will be made
there is never any gaps in the Earth’s crust so when tectonics crust pull apart magma from the mantle rises up and solidifies to fill the space with new land

• If continental pulls apart from continental then the same process occurs → magma erupts to the surface cools and solidifies
  the new crust often forms a (volcano)

Question 3

Example of constructive plate margin

Answer 3

Mid - Atlantic ridge → mountain chains and new crust is being created ( the ridge can be viewed from Thingvellir,Iceland)

Question 4

What is the rate of growth of the mid-atlantic ridge per year?

Answer 4

2.5cm per yr

Question 5

Do constructive plate margins create volcanos or earthquakes

Answer 5

Volcanoes → not earthquakes as there is no friction / contact between plates with the lava coming out is basaltic

Question 6

Characteristics of a destructive - subduction plate margin

Answer 6

Two plates (one oceanic and one continental)

• Denser (heavier)oceanic crust forced down underneath the lighter continental crust
• Subduction causes the oceanic plate to deform and partially melt(in the benioff zone) , adding pressure and creating a pool of magma under the continental plate.

Question 7

Example of destructive subduction plate margin

Answer 7

Andes mountains

Question 8

What plates are the plate boundaries of Andes found on?

Answer 8

( made up of the Nazca plate (oceanic plate) and the South American plate (continental plate)

Question 9

Do subductive destructive plate margins cause volcanoes and/or earthquakes

Answer 9

Volcanoes + earthquakes
* silica rich acidic lava
* alot of gas produce → very explosive
* long periods of inactivity

Question 10

Characteristics of destructive - collisional plate margins

Answer 10

When continental plates meet → subduction cannot occur because they both have the same density.

• the plates forced together at great pressure so the rocks crumble together and for massive mountains chains (known as fold mountains)
• Can be known as upwelling to form the mountains

Question 11

What are the examples of collision plate boundaries?

Answer 11

Himmalayas - still growing today

Question 12

What are the plate boundaries of the himmalayas?

Answer 12

( on the Indian and Eurasian plates moving towards each other )

Question 13

Do voclanoes or earthquakes occur at collisional plate boundaries?

Answer 13

• Earthquakes → due to the increased pressure/friction from the contact
• No volcanoes as no gap is created for magma to come up as they both upwell together

Question 14

Characterisics of conservative plate boundaries

Answer 14

When plates move alongside each other in opposite or the same direction but at different speeds so earthquakes occur

• plate margins are made up of brittle and jagged so tis difficult for the to move past eachother
• Sometimes plate get stuck causing for the pressure to build until suddenly they jerk releasing this pressure → causes the earthquakes

Question 15

Example of conservative plate boundary

Answer 15

San Andreas Fault on Western coast of North America → moving in opposing directions Pacific moving - NW North American plate - SE

Question 16

Does volcanic or earthquake activity occur at conservative plate margin?

Answer 16

Earthquakes