Module 1 - Moving Continents

Question 1

When and how was the earth formed?

Answer 1

4.57 billion years ago,
FORMED:
1. dense gas clouds compressed because of gravity and the centre became very hot and heavy (creating sun) 2. The matter on the outskirts was pushed out into because of solar winds (creating big bang) 3. The matter formed together because of gravity and came together to form proto plants - earth

Question 2

What are the properties of continental crust

Answer 2

density - 2.8g/cm3
composition - granite
thickness - 32km
temperature - 22c
SOLID

Question 3

What are the properties of oceanic crust

Answer 3

density - 3.2g/cm3
composition - basalt
thickness - 8km
temperature - 22c
SOLID

Question 4

What are the properties of the mantle

Answer 4

composition - molten rock
thickness - 2900km
temperature - 800c at top 2000c at bottom
SOLID OR LIQUID WHEN MELTED

Question 5

Where is the lithosphere located

Answer 5

contains crust and top of mantle

Question 6

Where is the asthenosphere located

Answer 6

contains upper regions of mantle (below lithosphere)

Question 7

What are the properties of the outer core

Answer 7

composition - nickel and iron
thickness - 2400km
temperature - 5000c
LIQUID

Question 8

What are the properties of the inner core

Answer 8

composition - nickel, iron, sulfur
thickness - 2300km
temperature - 7000c
SOLID

Question 9

Explain the continental drift theory

Answer 9

the theory that all continents were once all joined together as a super continent that has overtime been separated into individual continents

Question 10

Explain the evidence of the continental drift theory - jigsaw like fit

Answer 10

how all separated continents fit together like a jigsaw into one large piece

Question 11

Explain the evidence of the continental drift theory - fossils

Answer 11

same species of fossils were found on continents a long way apart

Question 12

Explain the evidence of the continental drift theory - sediments

Answer 12

ancient rock crops were continuous from one continent to the other

Question 13

Explain the seafloor spreading theory

Answer 13

a theory proposing that new rocky crust was being formed at the ocean ridges and spreading out after subduction occurred forcing crust to sink into the earth forming trenches and melting crust so it rises up

Question 14

Explain the evidence of the seafloor spreading theory - magnetic striping

Answer 14

because rocks contain magnetite (particles that face north) rocks at equal distances on each side of the ridge were formed at the same time and so had their magnetic fields pointing in the same direction

Question 15

Explain the evidence of the seafloor spreading theory - age of seafloor

Answer 15

younger rocks are found near ridges whilst other rocks are found far away from ridges

Question 16

Explain the evidence of the seafloor spreading theory - sediment thickness

Answer 16

rocks are found far away from ridge are thicker because they have been gathering sediment for longer

Question 17

Explain how convection currents are thought to be a mechanism for plate movements

Answer 17

plates are dragged along as the hot magma in asthenosphere rises up and then flows under the plates, creating convection currents (hot air rising, cool air sinking) as liquid rock flows, the friction between it and the tectonic plates move them

Question 18

Explain australias movement over time (225 million years ago, 125 millio years ago, 65 million years ago)

Answer 18

225 million - all continents were in a super continent called pangaea
125 million - half of the continents were separated from the other half and australia was in ther southern half called gondwana
65 million - aus separated from gondwana

Question 19

What are the 10 main plates

Answer 19

Pacific
North American
Cocos 
Nazca
Indo-Australian
South American
African
Eurasian
Indian 
Antarctic