Crust, Currents, Plates

Question 1

What is the earth made from, 4 things?

Answer 1

Inner core
Outer core
Mantel
Crust

Question 2

What is the lithosphere?

Answer 2

The solid top layer of crust in which plates are formed, consists of crust and upper mantel

Question 3

What is asthenosphere?

Answer 3

Soft, plastic like rock in the upper mantel just below the lithosphere

Question 4

What is the earths core temperature roughly?

Answer 4

5000 to 7000 degrees Celsius. That’s about as hot as the surface of the sun, but vastly cooler than the suns interior

Question 5

What’s the first stage of convection currents in the mantle?

Answer 5

Heat source- radioactive decay in the earths core (iron + nickel)

Question 6

What is the second stage of CC ?

Answer 6

The heat cools and sinks back down to be reheated

Question 7

What is the third stage of CC?

Answer 7

Semi molten rock spreads out carrying the above plate with it

Question 8

What is the forth stage of CC?

Answer 8

Direction of plate movement due to convection current below ( <— —>)

Question 9

What is the fifth stage of CC?

Answer 9

The rising limb of convection current. Heated rock in the mantle rises as it is less dense

Question 10

What is slab pull?

Answer 10

At subduction zones gravity “pulls” the oceanic plate down into the mantle. This destroys crust material and keeps the earth in shape

Question 11

What is ridge push?

Answer 11

The process of material pushing out from the ridge

Question 12

Thickness of continental crust vs oceanic

Answer 12

30-70 km thick vs 5-10 km

Question 13

Age of continental crust vs oceanic

Answer 13

As old as 4 billion vs 200 million

Question 14

Density of continental crust vs oceanic

Answer 14

2.7g/cubic cm vs 3g/cubic cm

Question 15

Mineral content to continental crust vs oceanic

Answer 15

Silicate and oxides vs silicate and magnesium

Question 16

Rock type of continental vs oceanic crust

Answer 16

Granites vs basalts

Question 17

What are the 5 evidences of plate tectonics?

Answer 17

Jigsaw fit
Geological fit
Fossil evidence
Tectonic fit
Paleomagnetism

Question 18

What is paleomagnetism?

Answer 18

Paleomagnetism is the study of the record of Earth’s magnetic field preserved in rocks and sediments. It helps scientists understand the history of the Earth’s magnetic field, including pole reversals and past movements of tectonic plates

Question 19

What is a constructive plate boundary?

Answer 19

2 plates are moving apart creating a gap in the middle for magma to rise up through.
Volcanoes form here but don’t erupt with force as the magma escapes quickly
Earthquakes occur e.g. mid Atlantic ridge
Rift valleys occur as land fall into the space left as plates move apart

Question 20

What is a destructive plate boundary?

Answer 20

Dense oceanic plate descends below less dense continental plate.
As the plate descends it is melted due to friction with the continental plate, forming hot, liquid magma, which rises through cracks in the continental plate and form volcanoes as it reaches the surface

Question 21

What is a collision plate boundary?

Answer 21

Occurs when two plates of similar densities move together i.e. a continental with another continental. This causes the material between them to buckle and rise up, forming fold mountains. E.g. the Himalayas (chain of fold mountains), they have been formed by the African plate colliding into the Eurasian plate

Question 22

What is a conservative plate boundary?

Answer 22

When two plates slide past each other along a fault (weakness).
No volcanoes occur here but earthquakes do occur.
Example includes the San Andreas fault in California