Surface Features in New Zealand

1. Surface Features in New Zealand Science NCEA 1.13 SJ Gaze

2. Objectives • Cross-section of the Earth • Theory of plate tectonics • Sea floor spreading and subduction zones • Earthquake and volcanic activity • Volcanic forms and formation • Mountain uplift • Weathering • Erosion • Fossil formation and dating • Stratigraphic column analysis • Geological events –faulting, subduction, deposition, igneous intrusion • Main rock types and formation • The rock cycle

3. What does the Earths interior look like? The thin layer of solid rock which covers the Earth is called the crust. SJ Gaze

4. What does the Earths interior look like? The crust is made up of the thick continental crust that forms the land and the much thinner oceanic crust that makes up ocean floors.

5. What does the Earths interior look like? Under this is the mantle. The middle of this is molten - so the upper mantle and crust float on this. SJ Gaze

6. What does the Earths interior look like? The inner layer is the core, which is a solid core surrounded by molten rock. SJ Gaze

7. How do we know what the Earths interior look like? When earthquakes occur they send waves through the earth. Different types of material with different temperatures will cause the waves to bend in different ways. Seismologists (earthquake scientists) record where in the world the waves come out and use that information to work out the size of layers, what the temperature of them is and what they are made out of.

8. Plate Tectonics The earth’s crust is divided into different sized pieces called plates. They fit together to cover the earth. SJ Gaze

9. Plate Tectonics • The plates float on hot, semi molten magma • Deep in earths core nuclear reactions release huge amounts of heat energy. This heat is the main source of energy for moving the gigantic plates • This heat causes the magma in the lower mantle rock to expand and become less dense. • This magma rises in convection currents • When the magma currents get near the crust they are pushed sideways and travel in different directions • These immensely powerful currents slowly float the huge tectonic plates across the planets surface SJ Gaze

10. Plate Tectonics The Lithosphere, the crust and top part of the mantle, is divided into large areas called plates, which are constantly moving The plates move slowly over the asthenosphere, which is the molten layer in the mantle, about 3cm a year. They can move towards each other, apart from each other or shift sideways Because all plates fit together, movement of one plate effects all plates around it The study of plate movement is called plate tectonics SJ Gaze

11. Evidence for Plate Tectonics • Evidence supports the conclusion that 200 million years ago, at the start of the Mesozoic era, all the continents were attached to one another in a single land mass, which has been named Pangaea. • During the Triassic, Pangaea began to break up, first into two major land masses: • Laurasia in the Northern Hemisphere and • Gondwana in the Southern Hemisphere. • The present continents separated at intervals throughout the remainder of the Mesozoic and through the Cenozoic, eventually reaching the positions they have today. SJ Gaze

12. Evidence for Plate Tectonics Shape of the Continents – close fit of continents • The east coast of South America and the west coast of Africa match especially at the boundaries of the continental slopes rather than the shorelines. Geology – similar rock patterns • In both mineral content and age, the rocks on the coast of Brazil match precisely those found on the west coast of Africa. • The low mountain ranges and rock types in North America match parts of Great Britain, France, and Scandinavia. Fossils – patterns in distribution • The same fossil reptiles found in South Africa are also found in Brazil and Argentina.

13. Evidence for Plate Tectonics The continents have gradually moved from one large land mass into the continents we know today. This movement has been slow but the time scale is large. The continents are still moving today.

15. Plate Tectonics

17. Plate Movement • When plates move the continents sitting on top of them move as well. • Plates can either; • Move away from each other – divergent boundary • Move towards each other – convergent boundary • Move sideward pass each other – transverse boundary SJ Gaze

18. Divergent Boundary A divergent boundary is where the tectonic plates are separating. New crust is made from cooling magma oozing up between the plates Some spreading boundaries are places where the crust is sinking downward as it is stretched thin SJ Gaze

19. Convergent Boundary A Convergent Boundary is the opposite of a divergent boundary. Typically you will see a converging boundary on a tectonic plate that is on the opposite side of a divergent boundary SJ Gaze

20. Convergent Boundary Sometimes you'll see volcanic activity at converging boundaries where plates are crashing into each other. When one plate (usually the lighter continental crust) rides up over the top of the other it's called a Subduction zone one plate margin slides under the other and melts into magma as it moves downwards SJ Gaze

21. Convergent Boundary As a plate moves in one direction it collides with the adjacent plate on its "front" end, while the trailing end of the plate is being pulled and stretched (spreading) from the plate on the other end. The colliding plates can cause a pushing up of land and the forming of a mountain range along the edge of a plate.

22. Transform fault Boundary Transform fault boundaries are places where the two plates are just sliding past each other. Of major importance are the earthquakes that are triggered along fault boundaries. SJ Gaze

23. Transform fault Boundary Fault seen through plantation Aerial view of the San Andreas fault slicing through the Carrizo Plain in the Temblor Range SJ Gaze

24. Plate Boundary Summary

25. Plate Boundary Summary Divergent Boundary Convergent Boundary Transform plate Boundary

26. Mountain uplift New mountains are built when rocks are pushed upward by movement of the tectonic plates. SJ Gaze

27. Mountain uplift Mountains can also be made when the ground is pushed up by plate movement Fold mountains are formed when layers of rock become buckled

28. Mountain uplift Block mountains are formed when giant lumps of rock rise or fall SJ Gaze

29. Mountain uplift Volcanic eruptions also create mountains. Lava and ash left behind after an eruption remain as land and mountains SJ Gaze

30. Volcanic eruptions • When tectonic plates collide, one plate may slide below the other (called the subduction zone). • The sinking plate melts from heat created by friction. • Magma is produced and may force its way to the surface, creating a volcano. • The explosive effect is known as an eruption. SJ Gaze

31. Mt Ruapehu erupting SJ Gaze

32. Shield Volcanoes Shield Volcanoes  are built almost entirely of fluid lava flows.  During their formation, flow after flow pours out of the volcano's vent in all directions. This results in a broad, gently sloping cone with flat conical shape, which looks a little like the shield of an ancient warrior. Some of the largest volcanoes in the world are Shield Volcanoes. The Hawaiian Islands are composed of linear chains of Shield Volcanoes. SJ Gaze

34. What causes earthquakes Earthquakes occur when two tectonic plates move suddenly against each other. The rocks usually break underground at the hypocentre and the earth shakes. Waves spread from the epicentre, and the point on the surface above the hypocentre. If a quake occurs under the sea it can cause a tsunami. In a strike-slip fault, the blocks of rock move in opposite horizontal directions. These faults form when crust pieces slide along each other at a transform plate boundary.

35. What causes earthquakes As plates move the strain causes brittle rock to crack These cracks, called faults, are often weak zones where more movement or cracking may occur Constant movement of plates causes pressure to build up at faults, and at the boundaries of the plates If there is a sudden slippage of rock, this pressure is released quickly and an earthquakeoccurs SJ Gaze

36. The Alpine fault The Alpine Fault, is about 600km through the middle of the South Island. It’s the boundary of the Pacific and Australian Plates. Horizontal movement of the Alpine Fault is about 30m per 1000 years, very fast by global standards. A new fault line was discovered when the February 22 Earthquake occurred in Christchurch. This was an extension off the Alpine fault and was in the form of a strike slip fault

37. Earthquake waves

38. Earthquake waves There are 3 main types of seismic waves are generated when faulting triggers an earthquake. All the seismic waves are generated at the same time, but travel at different speeds and in different ways. Body waves penetrate the earth and travel through it, while surface waves travel along the surface of the ground. Primary and secondary waves are body waves. Primary waves (P-waves) travel the fastest and can move through solids and liquids. The P-wave energy causes the ground to move in a compressional motion in the same direction that the wave is traveling. Secondary waves (S-waves) are slower and travel only through solids. The S-wave energy causes the ground to move in a shearing motion perpendicular to the direction of wave movement. Surface waves can cause rolling motion or sideways movement. These waves results in ground heave and swaying buildings. Surface waves cause the most devastating damage to buildings, bridges, and highways.

39. Liquefaction

40. Why Does NZ have so many earthquakes? New Zealand is on the top of two plates moving with transverse motion.

41. Types of rocks Igneous Metamorphic Sedimentary SJ Gaze

42. Types of rocks Igneous Metamorphic Sedimentary SJ Gaze

43. Types of rocks

44. Types of rocks SJ Gaze

45. SJ Gaze

46. Classification of Igneous Rocks Scoria obsidian andesite Pumice rhyolite basalt Volcanic(extrusive) Plutonic (intrusive) crystalisation granite diorite gabbro SJ Gaze

47. SJ Gaze

48. Classification of Igneous Rocks SJ Gaze

49. Classification of Sedimentary Rocks Related to water flow Mudstone is a fine-grained rock whose original particles were clays or muds. Mud rocks, such as mudstone and shale (that show layers) comprise some 65% of all sedimentary rocks. Mudstone may show cracks or fissures, like a sun-baked clay deposit. Siltstone is a sedimentary rock which has a composition intermediate in grain size between the coarser sandstones and the finer mudstones. Sandstone is composed mainly of sand-size grains. Sandstone may be any colour. Because of the hardness of the individual grains, uniformity of grain size, sandstone is an excellent material for building and paving coal A conglomerate is a rock consisting of individual stones that have become cemented together. Conglomerates consist of rounded fragments. SJ Gaze

50. Classification of Sedimentary Rocks Related to water flow Mudstone is a fine-grained rock whose original particles were clays or muds. Mud rocks, such as mudstone and shale (that show layers) comprise some 65% of all sedimentary rocks. Mudstone may show cracks or fissures, like a sun-baked clay deposit. Siltstone is a sedimentary rock which has a composition intermediate in grain size between the coarser sandstones and the finer mudstones. Increasing Grain (clast) size Sandstone is composed mainly of sand-size grains. Sandstone may be any colour. Because of the hardness of the individual grains, uniformity of grain size, sandstone is an excellent material for building and paving A conglomerate is a rock consisting of individual stones that have become cemented together. Conglomerates consist of rounded fragments. SJ Gaze