Yr 8 science revision

Question 1

1. Name the three types of plate boundaries.

Answer 1

1. Convergent, divergent, transform.

Question 2

2. How is lava different to magma

Answer 2

2. Lava is the molten rock that erupts out of a volcano and is on the surface whereas Magma is molten rock that is under the ground.

Question 3

3. How do convection currents, slab pull, and ridge push relate to the tectonic plates moving?

Answer 3

Both forces unevenly contribute to the subduction of an oceanic tectonic plate into the Earth’s mantle, contributing to the driving of convection currents.

Question 4

4. What are the four layers of the Earth?

Answer 4

4. Crust, Mantle, Outer Core, Inner Core

Question 5

5. What is the difference between an extrusive igneous rock and an intrusive igneous rock?

Answer 5

5. An extrusive igneous rock is formed from lava. It cools down very quickly creating small to no crystals inside the rock whereas intrusive igneous rocks are formed when magma slowly cools down underneath the surface creating large crystals.

Question 6

6. Explain continental drift

Answer 6

movements of continents relative to one another

Question 6

7. Give an example of a landform or natural disaster that occurs on a Transform Boundary.

Answer 6

7. Large Earthquakes or Tsunamis

Question 7

8. Give an example of a landform or natural disaster that occurs on a divergent boundary.

Answer 7

8. Mid ocean ridges, rift valleys, shield volcanoes, small earthquakes

Question 8

9. Give an example of a landform or natural disaster that occurs on a convergent boundary.

Answer 8

9. Fold mountains, ocean trenches, island arcs, stratovolcanoes, large earthquakes

Question 9

Describe the process of subduction

Answer 9

10. Subduction is when an oceanic plate runs into a continental plate and slides beneath it on a convergent boundary. One tectonic plate is heavier and sinks into the mantle to be remelted and recycled.

Question 10

11. What is the shape of a Shield Volcano?

Answer 10

Gentle slopes

Question 11

What is the shape of a Stratovolcano?

Answer 11

12. Tall, steep, conical

Question 12

What is sea floor spreading?

Answer 12

13. Sea floor spreading is when new and fresh areas of oceanic crust are formed because of magma coming to the surface. This was one piece of evidence that supported Alfred’s continental drift theory.

Question 13

14. What term best describes each of the following: a) plates that collide together, b) plates that slide parallel passed each other but in opposite directions and c) where new crust is created.

Answer 13

14. A) Convergent B) Transform C) Divergent

Question 14

15. What are the 7 major tectonic plates?

Answer 14

15. Australia, Antarctica, North America, South America, Eurasia, Africa, Pacific

Question 15

16. What geological structure can occur on a convergent plate boundary?

Answer 15

16. Fold mountains, ocean trenches, island arcs, stratovolcanoes.

Question 16

18. How are fossils formed?

Answer 16

18. Fossils are formed when sediment covers an organism quickly. The sediment encases the remains of the organism. Water dissolves the bones/shells etc leaving behind the imprint. This is a natural mould. Water rich in minerals will fill this space, crystals can form creating a fossil.

Question 16

17. What geological structure can occur on a divergent plate boundary?

Answer 16

17. Mid ocean ridges, rift valleys, shield volcanoes

Question 17

19. Explain the unique features of a Shield Volcano.

Answer 17

19. A shield volcano – has gentle slopes, lava is runny and flows very quickly, it rarely explodes because there is less gas pressure in the runny lava.

Question 18

21. Explain why intrusive igneous rocks have large crystals.

Answer 18

21. Because the cool very slowly

Question 19

20. Explain the unique features of a Stratovolcano.

Answer 19

20. A stratovolcano – has tall steep sides shaped into a conical shape, highly explosive

Question 20

22. Explain why extrusive igneous rocks have small to no crystals.

Answer 20

22. because the cool from lava very quickly

Question 21

23. Explain why fossils are not found in igneous rock.

Answer 21

23. Fossils are not found in igneous rock because the intense heat and pressure will destroy the fossil. They can be found in metamorphic rock but may be deformed.

Question 22

24. Explain how metamorphic rocks are made. Give an example of a metamorphic rock.

Answer 22

24. Metamorphic rocks are made when other rock is put under heat and pressure, causes the original rock to be deformed, folded and changed due to the heat and pressure and recrystallisation. They may contain layers, deformed fossils, large crystals and are very dense. They are very strong. An example of Metamorphic rock – MARBLE

Question 23

Explain how igneous rocks are made. Give an example of an igneous rock.

Answer 23

25. Igneous Rock are formed from the cooling of lava or magma. Some examples are PUMICE, OBSIDIAN, BASALT.

Question 24

26. Explain how sedimentary rocks are made. Give an example of a sedimentary rock.

Answer 24

Sedimentary rocks are made from the collection or sediment (fragments of weathered rock, plant or animal material. The sediment collects and more and more layers are added and compacted together. Fossils can be found in this rock. This compaction then cements by chemicals to form a solid rock. EG LIMESTONE, SANDSTONE

Question 25

27. What plate boundary do earthquakes happen on?

Answer 25

27. Convergent (Large Earthquakes) Divergent (small Earthquakes) Transform ( large Earthquakes)

Question 26

Draw the Rock Cycle.

Question 27

29. In your own words explain the difference between the theory of continental drift and the theory of plate tectonics.

Answer 27

29. Continental drift is the theory proposed by Wegener that explained how the continents move over time. He explained how the continents were like a jigsaw and all the pieces fit together. Fossil and rock records show how these pieces fit together.

Question 28

30. List the four main pieces of evidence Wegner used to support his theory of continental drift.

Answer 28

30. Four pieces of evidence

Question 29

31. Why is Obsidian an example of extrusive igneous rock?

Answer 29

31. Because it has small to no crystals which means it came from very quick cooling lava

Question 30

32. Compare Shield and Stratovolcanoes.

Answer 30

32. A shield volcano sdkflsjdfklaj whereas a stratovolcano sdfsdfadf

Question 31

33. What rock is formed when magma cools down slowly?

Answer 31

33. Intrusive igneous rock

Question 32

34. What is weathering?

Answer 32

34. Weathering is the process of rock being broken down into smaller pieces and eventually turn into sediment. It can be caused by physical processes, biological processes and chemical processes. This is the first step in making sedimentary rock.

Question 33

35. What is erosion?

Answer 33

35. Erosion is the transportation of the weathered rock usually by wind or water. Natural forces moves the weathered rock to a location (ocean or lake) where it is deposited.

Question 34

36. What can sedimentary rocks be formed from?

Answer 34

36. Remains of living organisms and the remains of non-living (shells)

Question 35

37. What is subduction?

Answer 35

37. Subduction is when an oceanic plate runs into a continental plate and slides beneath it. The heavier plate will sink into the mantle where the rock is remelted and recycled.