PMT - plate tectonic theory

Question 1

what are the tectonic plates?

Answer 1

he lithosphere broken up into large slabs of rock

Question 2

why do plates move?

Answer 2

convection currents in the asthenosphere, which push and pull the plates in different directions

Question 3

what are convection currents caused by?

Answer 3

when the less dense magma rises, cools, then sinks

Question 4

where do the convection currents occur?

Answer 4

asthenosphere

Question 5

what is the asthenosphere?

Answer 5

toughest plastic liquid part of the outer mantle

Question 6

distinguish between the continental and oceanic crust

Answer 6

Continental crust:
- Thick (10-70km).
- Buoyant (less dense than oceanic)
- Mostly old (over 1,500 million years)
- Mainly granite, silicon, aluminium

Oceanic crust:
- Thin (6-10km)
- Dense (sinks under the continental crust)
- Young (200 million years old)
- Mainly basalt, silicon, magnesium

Question 7

what is the characteristics for the inner core?

Answer 7

high pressure, intense density, solid, iron nickel sulphur

Question 8

what is the characteristics for the outer core?

Answer 8

liquid extremely hot nickel
liquid iron with magnetic field

Question 9

what is the characteristics for the mantle?

Answer 9

solid but can act like a viscous fluid
upper mantle is the asthenosphere

Question 10

what is the characteristics for the crust?

Answer 10

baslatic rocks

Question 11

what two countries were connected proving plate tectonic theory?

Answer 11

brazil and nigeria

Question 12

who is the founder of plate tectonic theory?

Answer 12

alfred wegner

Question 13

what did wegner argue?

Answer 13

▪ Fossils of same type found in different places. South Africa and Brazil
▪ All landmasses used to be a part of the same continent

Question 14

when was plate tectonics finally accepted?

Answer 14

1960s

Question 15

what are seven pieces of evidence of plate tectonic theory?

Answer 15

▪ Jigsaw fitting geological fit of opposing continents

▪ Glacial evidence 

▪ If continental drift had not occurred then the ice sheet would have extended from the south pole to the equator 

▪ Carboniferous period 345 to 280 million years ago experienced a hot tropical climate as it was drifting from the southern hemisphere across the equator to northern 

▪ Fossil evidence eg south America and Africa had Mesosaurus fossils 

▪ Sea floor spreading - harry hess 1962

▪ Palaeomagnetism

Question 16

what happened during the carboniferous period?

Answer 16

345 to 280 million years ago

hot tropical climate was drifting from the southern hemisphere across the equator to northern