Plate margins and magma plumes

Question 1

How are ‘young’ fold mountains formed?

Answer 1

formed due to collisons/subductions

Question 2

How old are ‘young’ fold mountains

Answer 2

generally 30-40 million years old

Question 3

Give an example of ‘young’ fold mountins?

Answer 3

the Himalayas

Question 4

Give an example of ‘old’ fold mountains?

Answer 4

The Cairngorms

Question 5

Define syncline.

Answer 5

dip in mountains

Question 6

Define anticline.

Answer 6

raise in mountains

Question 7

What can a destructive plate margin also be called?

Answer 7

Convergent/ collision

Question 8

What can a conservative plate margin also be called?

Answer 8

Transform

Question 9

What can a constructive plate margin also be called?

Answer 9

Divergent

Question 10

What happens when continental and continental plates collide?

Answer 10

fold mountains form

Question 11

What happens when Oceanic and continental plates collide?

Answer 11

subduction

Question 12

What happens when oceanic and oceanic plates collide?

Answer 12

subduction

Question 13

What is the Benioff zone?

Answer 13

An inclined zone in which many deep earthquakes occur, situated beneath a destructive plate boundary where oceanic crust begins to melt due to friction

Question 14

What is an ocean trench?

Answer 14

A linear depression on the sea floor which runs parallel to the plate boundary and is caused by the subduction of one plate under another

Question 15

What is an Accretionary wedge?

Answer 15

Scraped sediment

Question 16

What is the plate margin at the Himalayas?

Answer 16

Collision plate margin

Question 17

What plates are at the Himalayas?

Answer 17

Indo-Australian and Eurasian (both Continental)

Question 18

What has formed at the Himalayas?

Answer 18

‘young’ fold mountians

Question 19

How long is the fold mountain chain at the Himalayas?

Answer 19

2,400km long

Question 20

What is the plate marigin at the Andes?

Answer 20

Destructive plate margin

Question 21

What are the plates at the Andes?

Answer 21

Nazca (oceanic) and South American (continental)

Question 22

What has formed at the Andes?

Answer 22

Ocean trench

Question 23

How deep is the ocean trench at the Andes?

Answer 23

4000m deep

Question 24

What is the plate margin at the Caribbean?

Answer 24

Destructive plate margin

Question 25

What are the plates at the Caribbean?

Answer 25

Caribbean (oceanic) and North American (oceanic)

Question 26

What has formed at the Caribbean?

Answer 26

Puerto Rico trench and the Island Arc chain

Question 27

Give an example of a ridge,

Answer 27

Mid-Atlantic ridge

Question 28

Give an example of an ocean trench.

Answer 28

Puerto Rico trench/ Mariana trench- Philippines

Question 29

What plates are at the mid-Atlantic ridge?

Answer 29

Oceanic and Oceanic

Question 30

How does a ridge form?

Answer 30

- convection currents pull the tow pieces of oceanic crust apart - where the crust separates it leaves a thinner bit of lithosphere that rises - the weakened crust allows magma to escape - the lava builds up in layers to for a ridge

Question 31

What are the characteristics of a ridge?

Answer 31

-Longest features on the planet - transform faults at right angles to the plate boundary

Question 32

What plates create a rift valley?

Answer 32

Continental and continental

Question 33

What are the characteristics of a rift valley?

Answer 33

- triggered by plumes of magma - normal (parallel) faults - volcanoes - lakes of valley floors

Question 34

Define magma plumes.

Answer 34

Areas of high heat flow within the mantle

Question 35

Give some characteristics of magma plumes.

Answer 35

- random distribution - they occur on any plates (middle of plates or plate boundaries)

Question 36

Give an example of a current hotspot.

Answer 36

Hawaii

Question 37

How old is Hawaii hotspot?

Answer 37

less than 0.7 million years old

Question 38

How long is the Hawaii island?

Answer 38

2,600km long

Question 39

How far is Hawaii from the closest plate boundary?

Answer 39

3,200 km

Question 40

How does volcanic hotspots form?

Answer 40

created as plumes of magma rise through the earths mantle

Question 41

The oldest islands are _______ from the hotspot

Answer 41

furthest

Question 42

Why do volcanic earthquakes occur?

Answer 42

generated by magma movement

Question 43

Why do tectonic earthquakes occur?

Answer 43

because of structural weaknesses at the base of the volcanoes or within the crust below

Question 44

What is basaltic lava?

Answer 44

- runny lava which allows gas to escape easily which leads to effusive eruptions

Question 45

What is the temperature of basaltic lava?

Answer 45

over 1000 degrees Celsius

Question 46

What is Andesitic lava?

Answer 46

sticky lava which traps gas

Question 47

How does magma plums create a chain of islands?

Answer 47

- convection currents draws heat to a section of the lithosphere - The mantle makes its way through the crust - Volcanoes form as the magma escapes - As the tectonic plates move over the hotspot the volcanoes move further away, reducing their levels of vulcancitity - This process starts again with a new volcano forming