Plate Tectonics

Question 1

Crust

Answer 1

Earth’s outer shell, between 6-70km thick

Question 2

Mantle

Answer 2

Molten/ semi-molten layer rock layer

Question 3

Outer Core

Answer 3

Molten outer layer of the core, mainly iron

Question 4

Inner Core

Answer 4

Solid centre, made of iron and nickel alloys- up to 5000°c

Question 5

Asthenosphere

Answer 5

Layer beneath the lithosphere that’s semi-molten and the plates float on

Question 6

Lithosphere

Answer 6

Crust and the rigid upper section of the mantle, divided into the tectonic plates

Question 7

Oceanic Crust- Thickness

Answer 7

6-10km

Question 8

Oceanic Crust- Age

Answer 8

> 200million

Question 9

Which is denser- oceanic or continental crust?

Answer 9

Oceanic

Question 10

Oceanic Crust- Example of rock

Answer 10

Basalt

Question 11

Continental Crust- Thickness

Answer 11

30-70km

Question 12

Continental Crust- Age

Answer 12

<1500million

Question 13

Continental Crust- Example of rock

Answer 13

Granite

Question 14

What are the 2 internal energy sources?

Answer 14

Primordial Heat

Radiogenic Heat

Question 15

What’s primordial heat?

Answer 15

Heat left over from Earth’s formation

Question 16

What’s radiogenic heat?

Answer 16

Heat produced by the decay of isotopes like Uranium 238

By far the greatest source, but slowly diminishing

Question 17

Explain Alfred Wagner’s theory (1912)

Answer 17

Continental Drift- 300 million years ago Pangea existed

Question 18

List 5 pieces of evidences supporting continental drift

Answer 18

Fossil Fit
Tectonic Fit
Geological Fit
Jigsaw Fit
Paleomagnetism

Question 19

Fossil Fit Example

Answer 19

Mesosaurus found in South Africa and East America

Question 20

What type of fossils are looked at? Why?

Answer 20

Land mammals

Don’t swim, don’t lay eggs

Question 21

Tectonic Fit Example

Answer 21

Caledonian mountain belt found in Scotland, Canada and Greenland- form a continuous linear pattern when reassembled

Question 22

Why does tectonic fit support Continental Drift?

Answer 22

As mountain belts have to be made under the same conditions in the same location

Question 23

Geological Fit Example

Answer 23

Mapping South America and West Africa reveals continuous rock outcrops over 2,000 million years old

Question 24

Jigsaw Fit Example

Answer 24

Coastlines of South America and West Africa match to a depth of 1,000m below current sea level

Question 25

How can gaps and overlaps in jigsaw fit be explained?

Answer 25

Coastal erosion Coastal deposition Rises in sea level Changes in land level

Question 26

How does paleomagnetism explain Continental Drift?

Answer 26

Roughly every 400 million years the Earth's magnetism changes At mid ocean ridges, there are striped symmetrical patterns where the rock has moved apart due to sea floor spreading Shows that the plates are moving

Question 27

Sea Floor Spreading

Answer 27

Movement of oceanic crust away from constructive plate margins at mid-ocean ridges

Question 28

Slab Pull

Answer 28

After subduction, the cooler, heavier edge of the lithosphere sinks into the mantle under its own weight, pulling the plate with in

Question 29

Ridge Push

Answer 29

The higher elevation at mid ocean ridges causes gravity to push the lithosphere that's further from the ridge

Question 30

Gravitational Sliding

Answer 30

Movement of tectonic plates as a result of gravity

Question 31

Benioff Zone

Answer 31

Where plates melt in the mantle due to increasing heat and friction

Question 32

Constructive Margin

Answer 32

Plates move apart | Magma rises from the asthenosphere and cools, filling the gap

Question 33

Constructive Margin Features (and examples)

Answer 33

Shield volcanoes- Eyjafjallajokull Earthquakes Rift valleys- East African Rift Valley Mid-Ocean Ridges- Mid-Atlantic Ridge

Question 34

Oceanic- Oceanic Margin

Answer 34

2 Oceanic plates move towards eachother Faster/ denser subducts Melts in Benioff Zone Less dense molten material rises

Question 35

Oceanic- Oceanic Margin Features (and examples)

Answer 35

``` Ocean trenches- Mariana Trench Island Arcs- West Indes Earthquakes Composite volcanoes- Montserrat Tsunamis- Boxing Day ```

Question 36

Oceanic- Continental Margin

Answer 36

Oceanic and continental move towards eachother Denser oceanic subducts Melts in Benioff Zone Less dense molten material rises

Question 37

Oceanic- Continental Margin Features (and examples)

Answer 37

Ocean Trenches- Peru-Chile Trench Composite volcanoes- Cotopaxi Fold mountains- Himalayas

Question 38

Continental- Continental Margins

Answer 38

Continental plates move towards eachother Both plates have a lower density than asthenosphere Can't subduct Collide and rise upwards

Question 39

Continental- Continental Margin Features (and examples)

Answer 39

Earthquakes | Fold Mountains- Himalayas

Question 40

Conservative Margin

Answer 40

Plates move past eachother Friction between plates= stress builds Suddenly released

Question 41

Conservative Margin Features (and examples)

Answer 41

Fault line- San Andreas | Shallow earthquakes

Question 42

Hotspots

Answer 42

Small area with unusually high concentration of radioactive elements below the surface (Magma Plumes)

Question 43

Hotspot Feature (and example)

Answer 43

Shield volcanoes- Mauna Loa, Hawaii

Question 44

Magma Plume

Answer 44

Rising column of hot rock at a plate margin or through a plate