1. Geology Notes Part 8

2. What is continental drift? The theory that states that all the continents were once joined together but over time have split and drifted apart

3. What is sea-floor spreading? The process by which new ocean floor forms as magma rises to the surface and solidifies As the tectonic plates move away from each other, the sea-floor spreads and magma fills in the gap

4. What is a mid-ocean ridge? A undersea mountain chain that forms as magma rises from the asthenosphere and creates new sea floor as tectonic plates move apart Forms at divergent plate boundaries

5. What is Pangea? The single super- continent formed 245 million years ago by the present continents

6. What is the Theory of Plate Tectonics? The theory that states that the Earth’s crust is made up of rigid plates that move

7. What is the Theory of Plate Tectonics? The motion of the plates causes continental drift

8. As plates move apart at divergent boundaries mid- ocean ridges form. As oceanic plates collide with continental plates, trenches form as the oceanic plate is subducted. When two continental plates collide mountain ranges form. Earthquakes and volcanoes occur along most plate boundaries. How does the Plate Tectonic theory account for features and processes that occur on or near the Earth’s surface?

9. What is the relationship between the rock cycle and the Plate Tectonic Theory?

10. What is the geological evidence that indicates climates were colder throughout Earth’s history? Glacier evidence is found in Africa and South America. Today their climates are far to warm for glaciers to form.

11. What is the evidence that indicates Africa and South America were once part of a single continent? similar coastline shapes mountain chains that fit together in a continuous chain with rock types and ages that match. many of the same fossils; matching glacial grooves

12. Geology Notes Part 9

13. Describe the three types of tectonic plate boundaries and the geographic features associated with them. Convergent boundaries - Plates collide, causing trenches when oceanic plates subduct under continental plates; mountains form when two continental plates collide; volcanoes and island arcs form when two ocean plates collide. Divergent boundaries - Plates move apart, causing mid-ocean ridges and continental rifts Transform boundaries - Plates slide past each other

14. Describe the three types of tectonic plate boundaries.

15. What causes tectonic plates to move? Convection within the mantle; when the warmer rock rises, cooler rock near the surface sinks

16. How do rocks bend, fold, and break to create faults? when plates move together and put stress on them land features that start as folds and faults can eventually become mountains

17. Geology Notes Part 8

18. What causes earthquakes? When plates slide past each other, collide, or move part http://news.bbc.co.uk/cbbcnews/hi/newsid_4130000/newsid_4132300/4132319.stm

20. What causes faults to form? When rocks are put under great stress and pressure, they begin to bend. Once the elastic limit is reached, they break forming a fault.

21. What is the elastic rebound theory? It explains how rocks spring back into their original shape after they have been deformed by seismic forces

22. What is a seismograph? Instruments that record the vibrations of the Earth during an earthquake

23. How are earthquakes measured? The Richter scale of magnitude is a scale used that measures the amplitude (height) of seismic waves

24. Richter Scale 1.0 = 32 x energy 2.0 =1024 x 3.0 = 32,000 x 4.0 = 1,000,000 5.0 = 32,000,000 6.0 = 1,000,000,000 7.0 = 32,000,000,000 8.0 = 1,000,000,000,000 9.0 = 32 x 10 13 (320000000000000)

25. What is the epicenter? The position on the Earth’s surface directly above the focus of an earthquake The point at which stress breaks the friction lock between two plates of the Earth’s crust What is the focus?

26. What is the relationship between Plate tectonics and earthquakes? Most earthquakes occur along plate boundaries. Most large earthquakes occur along convergent plate boundaries. Earthquakes occur deeper and deeper as on plate is being subducted Under another plate.

27. What are Seismic waves? Seismic waves are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. They are the energy that travels through the earth and is recorded on seismographs.

28. What are Seismic waves? The two main types of waves are body waves and surface waves. Body waves can travel through the earth's inner layers, but surface waves can only move along the surface of the planet like ripples on water.

29. Seismic waves

30. P-Waves –Primary (they arrive first), Pressure, or Push-Pull. Material expands and contracts in volume and particles move back and forth in the path of the wave. P-waves are essentially sound waves and travel through solids, liquids or gases. What are Seismic waves?

31. S-Waves –Secondary (arrive later), Shear, or Side- to-side. Material does not change volume but shears out of shape and snaps back. Particle motion is at right angles to the path of the wave. Since the material has to be able to "remember" its shape, S- waves travel only through solids.

32. What are Seismic waves? Surface Waves –Several types, travel along the earth's surface or on layer boundaries in the earth. The slowest waves but the ones that do the damage in large earthquakes.

33. What are Seismic waves?

34. How can seismic waves be used to identify the properties of Earth’s interior? By recording seismic waves around the world shadow zones are revealed due to the inability of S waves to travel through liquids. Seismic waves also bend (refract) when they pass through different materials. By measuring the speed, strength, and changes in the seismic waves Earth’s interior has been calculated

35. What impact do earthquakes have on humans? Earthquakes cause buildings and other structures to collapse which causes the most injury and death. Other dangers include landslides, fires, explosions from broken gas lines, and floods from collapsing dams.

36. Where would you be most likely to feel a minor earthquake? Someone on the top floors of a tall building.

37. Geology Notes Part 9

38. What is a volcano? A vent or fissure in the Earth’s surface through which magma and gases are expelled

39. What is the difference between lava and magma? lava is the molten rock or magma that has reached the surface

40. Where do volcanoes generally occur? They generally occur along plate boundaries when plates collide or move apart

41. What are the two different types of volcanic eruption? nonexplosive eruptions produce calm flows of lava; explosive eruptions are rare and rapidly erupt ash and rock into the atmosphere

42. How does the composition of lava affect the eruption of the volcano? Lava that has high silica contents is thick and sticky and traps gases like water vapor in it easily. This leads to explosive eruptions due to the built up pressure. Lava that has little silica is thin and runny and releases gases in it. This leads to quite/nonexplosive eruptions

43. What are the different types of lava? Aa lava is thin and froms brittle jagged crust as it cools Pahoehoe lava flows slowly forms a glassy wrinkled crust

44. What are the different types of lava?

46. What is a shield volcano and how do they form? formed by quiet eruptions thin lava that spreads out over a wide area sides are not steep

47. Photograph of the Hawaiian volcano, Mauna Kea, with a light dusting of snow, seen from Kohala above Kamuela. Photograph by Eric Guinther provided to Wikipedia under GNU.

48. Belknap Shield Volcano, Oregon.

49. What is a cinder cone volcano and how do they form? Formed by moderatly explosive eruptions the tephra and pyroclastic material forms steep sides

50. Tavurvur, Rabaul Caldera, Papua New Guinea. A small explosion from Tavurvur sends an eruption column into the sky a few weeks after it began erupting on September 19, 1994. Lava erupted from the cone in October 1996 and flowed through the breach in the crater (left center).

51. Mount Veniaminof, Alaska. Steam rises from the cinder cone within the caldera of Mount Veniaminof in the final stages of an eruption in 1983-1984. Lava flows that spilled down the side of the cone (dark areas) melted a pit in the summit ice cap about 2.3 x 1 km in dimension.

52. What is a composite volcano and how do they form? Form from explosive eruptions followed by slower flow of lava forms alternating layers of pyroclastic material and lava Also known as a stratovolcano

53. Mount St Helens 1980

54. Mount St Helens 1980

55. Snow-covered Kanaga Volcano in Alaska erupts a small column of tephra, gas, and steam. Kanaga is a stratovolcano.

57. What is a hot spot? A volcanically active area far from a plate boundary

58. Current Eruption December 28, 2007 - Ash and steam spewing from Tungarahua volcano, Ecuador, South America

59. How can hot spots be used to determine the motion of tectonic plate? Using the distance of volcanoes (such as the Hawaiian Islands) and their age, the direction and rate of plate movement can be determined.

60. How can volcanoes change the atmosphere, hydrosphere, and other Earth systems. The lava, gas, and ash that erupt into the atmosphere can remain in the atmosphere and be dispersed around the world by global wind currents. The sulfur dioxide combines with water vapor to form sulfuric acid, which reflects the sun’s energy back into space. This can cause global temperatures to decrease. Also the acid rain has a negative impact on vegatation around the world

61. How can volcanoes be used to determine plate boundaries? Composite volcanoes usually form in straight lines along convergent plate boundaries as one plate is being subducted under another