1.2

Question 1

What is the structure of the earth?

Answer 1

crust (lithosphere, asthenosphere), mantle, occur core, inner core

Question 2

What is the asthenosphere?

Answer 2

The asthenosphere is just the upper layer of the mantle

(180km thick) creates convection currents

Question 3

What is the lithosphere?

Answer 3

The lithosphere is the crust and the very upper layer of the mantle (100km thick)

Question 4

What does the mantle consist of?

Answer 4

it is a thick, solid rocky substance of magma
85% of earth mass
2,900 kilometres (First 50km is hard rock, next 240km is hot and solid rock, last 100’skm is solid hot dense rock)
Largest layer in the earth
creates convection currents due to magma movemens
500-4000C hot

Question 5

What does the crust consist of?

Answer 5

oceanic crust is denser basaltic
continental crust is lighter granite
35km thick solid rock
floats on mantle layer

Question 6

What does the outer core consist of?

Answer 6

super hot magma molten rocks
made of Fe and Ni
2,200 km thick
4500C+
controls the earths magnetic properties

Question 7

What does the inner core consist of?

Answer 7

solid ball of Fe and Ni - denser
5000-6000C
hot as sun's surface
this melts the outer core
spinning more - magnetic properties
forced to vibrate like a solid

Question 8

What are the theories of plate tectonics?

Answer 8

mantle convection
slab pull
sub-duction
sea floor spreading

Question 9

What is plate tectonic theory?

Answer 9

the theory that huge slabs of earth surface are made up of rock and fit like a jigsaw and are the foundation of continents moving slowly

Question 10

What is the theory of convection currents?

Answer 10

1. That the earths inner core is radioactive and releases energy to the mantle and outer core.
2. The crust insulates the earth keeping it warm
3. This radioactive energy causes the lower mantle to melt,
4. Due to it melting it rises and the basaltic plastic rock rises, cools and becomes more dense and falls
5. This is repeated as it falls back to the core and warms up again
   This is how Pangaea became Laurasia then Gondwanaland

Question 11

What happens when the current in the mantle meets the crust?

Answer 11

when this happens the up welling magma forces crust apart spreading the floor as new magma is formed then cooled - as it sticks to the crust

Question 12

Why are where does the current sink?

Answer 12

The convection currents rise up due to being less dense.
At divergent boundaries to make ridges eg Mid-Atlantic.
This then cools down and sinks at convergent due to subduction as its denser.

Question 13

What is paleomagnetism?

Answer 13

study of symmetrical polarity patterns inside basaltic rock

Question 14

How does paleomagnetism prove sea floor spreading/plate movement?

Answer 14

because every few million years the poles switch so magnets change direction
Therefore, magnetic material in magma switches accordingly
Therefore, keeping track and having samples of rock with magnets that go opposite in parallel patterns.
Therefore, samples can be taken to prove changes in poles and movement of plates

Question 15

What did Alfred Wegener create the theory of?

Answer 15

the theory of continental drift and that the rock types varied across different continents but is some areas eg Eastern South America and western Africa have the same rocks and some similar fossils.
So for the rocks and fossils to be alike the animals must’ve been able to get there easily and rocks must’ve joined together.

Question 16

What did Harry Hess research/theory?

Answer 16

1. used sonar to research the ocean floor
2. discovered mid-Atlantic ridge
3. made a discovery that the closer to the coast the older the ocean floor
   4 .and that new crust must be made by molten rock from inside the earth
4. discovered that gravity helps slab pull and convergent zones destroying/creating rock

Question 17

What is the basic concept for slab pull?

Answer 17

at constructive margins land is made

and at convergent margins land is destroyed.

Question 18

Distinguish between two types of the earths crust?

Answer 18

Oceanic = younger, denser, basaltic crust that is 3x dense than the continental crust, beneath deep oceans
Continental = older, buoyant, lighter and less dense, habitat of humans, granite/andesitic

Question 19

What causes tectonic plates to move?

Answer 19

convection currents in the upper mantle

Question 20

What are 4 processes at work along a destructive plate boundary?

Answer 20

subduction
convection currents
ridge push
slab pull