OCR A-Level Geography - OCR A
Level Geography Questions With
Correct Answers Latest Updated
What are the 3 layers of the Earth? - CORRECT ANSWER-*Crust*
*Mantle*
*Core* (inner and outer)
What separates the crust and the mantle? - CORRECT ANSWER-*Moho*
What 2 layers does the upper mantle consist of? - CORRECT ANSWER-*Lithosphere* (semi-core)
Varies in thickness
Boundary with asthenosphere difficult to define (melts and becomes incorporated in
asthenosphere)
*Asthenosphere* extends 100-300km
Semi-molten/viscous - Allows rock to move due to high pressure in mantle.
Flowing slowly
What are continental and oceanic plates made up of? - CORRECT ANSWER-Lithosphere and
crust
Where do convection currents exist?
What do these do? - CORRECT ANSWER-Asthenosphere
Caused by vast amounts of heat generated in mantle.
,Semi-molten asthenosphere flows carrying with it the solid lithosphere and crust.
What are the properties of the *continental crust*? - CORRECT ANSWER-Thickness:
35km average (<30-70km)
Density:
2.6-2.7
Mineral composition:
Mainly granitic, silicon, aluminium
What are the properties of the *oceanic crust*? - CORRECT ANSWER-Thickness:
5-10km
Density:
3.0
Mineral composition:
Mainly basaltic, silicon and magnesium
What are the properties of the *mantle*? - CORRECT ANSWER-Thickness:
To a depth of 2900km
Density:
3.3 at Moho
5.6 at core
,Mineral composition:
Rich in magnesium and iron
Explain the movement of the crust caused by convection currents in the mantle. - CORRECT
ANSWER-Hot rock rises from lower to upper asthenosphere.
Hot rock spreads and cools, pushing plates apart.
Cool rock sinks back down towards core.
As (oceanic) plate subducts at ocean trenches, gravity pulls it under (*slab pull*).
Rising mantle pushes crust upwards at mid-ocean trenches, while gravity pulls it back down
(*ridge push*).
What was Alfred Wegener's big idea? - CORRECT ANSWER-250 million years (Carboniferous
period), all the Earth's continents fit together (*Pangea*).
Over time, continents have moved apart through *continental drift*.
Explain 3 pieces of (Wegener's) *geological* (rocks) evidence for continental drift. - CORRECT
ANSWER-*Mountain chains and rock sequences on opposite sides of oceans show close
similarities* (e.g. northeast Canada and northern Scotland).
- These mountains are likely to have been created together and then split apart as the
continents moved.
*Continents seem to fit together* (particularly South America and Africa).
- Suggests that continents once fit all together and continental drift has separated them.
, - (Erosion wouldn't've made them this shape).
*Evidence of glaciations 290 million years ago in southern Africa, Australia, South America, India
and Antarctica*.
- Suggests these land masses were joined during this time, located close to the South Pole.
- (India has a tropical climate now, and due to it's current location it wouldn't have been
glaciated in an ice age.
- Suggests India was one at a higher latitude further from the equator).
Explain 3 pieces of (Wegener's) *biological* (living) evidence for continental drift. - CORRECT
ANSWER-*Similar fossils of marine shellfish (e.g. brachiopods) were found in Australian and
Indian limestones*.
- Brachiopods are small shellfish that would be unlikely to cross open stretches of ocean
between Australia and India.
- Suggests India and Australia were once much closer together meaning the brachiopods have
been separated by continents moving apart.
*Similar reptile fossils found in South American and South Africa*.
- Reptiles wouldn't've been able to cross the ocean suggesting all land was once joined together.
- They are unlikely to have evolved the same in separate areas.
*Fossil from rocks younger than Carboniferous period show fewer similarities between animal,
suggesting they followed different evolutionary paths.
- These animals originally evolved together (during carboniferous period).
- Once the continents split the animals were separated.
- They evolved as their environments changed, becoming more different.
What is *paleomagnetism*? - CORRECT ANSWER-Changes in the Earth's polarity.
Level Geography Questions With
Correct Answers Latest Updated
What are the 3 layers of the Earth? - CORRECT ANSWER-*Crust*
*Mantle*
*Core* (inner and outer)
What separates the crust and the mantle? - CORRECT ANSWER-*Moho*
What 2 layers does the upper mantle consist of? - CORRECT ANSWER-*Lithosphere* (semi-core)
Varies in thickness
Boundary with asthenosphere difficult to define (melts and becomes incorporated in
asthenosphere)
*Asthenosphere* extends 100-300km
Semi-molten/viscous - Allows rock to move due to high pressure in mantle.
Flowing slowly
What are continental and oceanic plates made up of? - CORRECT ANSWER-Lithosphere and
crust
Where do convection currents exist?
What do these do? - CORRECT ANSWER-Asthenosphere
Caused by vast amounts of heat generated in mantle.
,Semi-molten asthenosphere flows carrying with it the solid lithosphere and crust.
What are the properties of the *continental crust*? - CORRECT ANSWER-Thickness:
35km average (<30-70km)
Density:
2.6-2.7
Mineral composition:
Mainly granitic, silicon, aluminium
What are the properties of the *oceanic crust*? - CORRECT ANSWER-Thickness:
5-10km
Density:
3.0
Mineral composition:
Mainly basaltic, silicon and magnesium
What are the properties of the *mantle*? - CORRECT ANSWER-Thickness:
To a depth of 2900km
Density:
3.3 at Moho
5.6 at core
,Mineral composition:
Rich in magnesium and iron
Explain the movement of the crust caused by convection currents in the mantle. - CORRECT
ANSWER-Hot rock rises from lower to upper asthenosphere.
Hot rock spreads and cools, pushing plates apart.
Cool rock sinks back down towards core.
As (oceanic) plate subducts at ocean trenches, gravity pulls it under (*slab pull*).
Rising mantle pushes crust upwards at mid-ocean trenches, while gravity pulls it back down
(*ridge push*).
What was Alfred Wegener's big idea? - CORRECT ANSWER-250 million years (Carboniferous
period), all the Earth's continents fit together (*Pangea*).
Over time, continents have moved apart through *continental drift*.
Explain 3 pieces of (Wegener's) *geological* (rocks) evidence for continental drift. - CORRECT
ANSWER-*Mountain chains and rock sequences on opposite sides of oceans show close
similarities* (e.g. northeast Canada and northern Scotland).
- These mountains are likely to have been created together and then split apart as the
continents moved.
*Continents seem to fit together* (particularly South America and Africa).
- Suggests that continents once fit all together and continental drift has separated them.
, - (Erosion wouldn't've made them this shape).
*Evidence of glaciations 290 million years ago in southern Africa, Australia, South America, India
and Antarctica*.
- Suggests these land masses were joined during this time, located close to the South Pole.
- (India has a tropical climate now, and due to it's current location it wouldn't have been
glaciated in an ice age.
- Suggests India was one at a higher latitude further from the equator).
Explain 3 pieces of (Wegener's) *biological* (living) evidence for continental drift. - CORRECT
ANSWER-*Similar fossils of marine shellfish (e.g. brachiopods) were found in Australian and
Indian limestones*.
- Brachiopods are small shellfish that would be unlikely to cross open stretches of ocean
between Australia and India.
- Suggests India and Australia were once much closer together meaning the brachiopods have
been separated by continents moving apart.
*Similar reptile fossils found in South American and South Africa*.
- Reptiles wouldn't've been able to cross the ocean suggesting all land was once joined together.
- They are unlikely to have evolved the same in separate areas.
*Fossil from rocks younger than Carboniferous period show fewer similarities between animal,
suggesting they followed different evolutionary paths.
- These animals originally evolved together (during carboniferous period).
- Once the continents split the animals were separated.
- They evolved as their environments changed, becoming more different.
What is *paleomagnetism*? - CORRECT ANSWER-Changes in the Earth's polarity.
