Unit 4 & 5 Geology of the Ocean, Water, Waves, and Tides

1. Unit 4 & 5Geology of the Ocean, Water, Waves, and Tides Mrs. Stahl Marine Biology

3. Some Facts • Solar system was formed more than 5 billion years ago, with Earth forming 400 million years later. • Surface was so hot that water could not remain there because there was no free oxygen gas in the atmosphere • Ocean began forming 4.2 billion years ago • Life first evolved in the ocean • Ocean covers 70.8%

4. How did the ocean form? Hypothesis is: Earth was composed of cold matter and over time energy from space and radioactive decay causes the temperatures to rise. Process continued for several hundred million years until the core of the Earth was hot enough to melt iron and nickel. Elements melted -> moved to the core-> raising temps to 2,000 C Molten material moved to the surface and spread out, continued to melt and solidify, creating our landscape separating the lighter elements from the denser ones.

5. They think that if there was any water present that it was stored up in the Earth’s minerals. Then continuous heating and cooling took place and water vapor was carried to the surface, it cooled, condensed, and formed the ocean!

6. Origin of Life • Atmosphere was originally made up of gases like carbon monoxide, carbon dioxide, methane, nitrogen, and ammonia. Oxygen is chemically active so any other free oxygen gas present would have combined with some other element forming oxides. Therefore, oxygen did not start to accumulate in the atmosphere until the evolution of modern photosynthesis. • Oxides- Chemical compound containing at least one oxygen atom as well as another element.

7. Biologists also theorize that the molecules (carbon monoxide, carbon dioxide, nitrogen, methane, and ammonia) formed and accumulated in the ocean and over time the ocean turned into a huge, highly concentrated bowl of nutrient soup.

8. The molecules then became organized and the first cells evolved. • There wasn’t any oxygen so the first cells had to be anaerobic. • The first cells were also heterotrophs or relied on others for food.

9. The oldest marine fossil is marine bacteria (cyanobacteria) and was found in NW Australia between 3.4 and 3.5 billion years old.

10. The Ocean Today

11. The Ocean Today 139 million square miles, 362 X 10^18 gallons 362,000,000,000,000,000,000 gallons of water Largest habitat on the planet Referred to as the world ocean

12. There are Four Major Basins Pacific Atlantic Indian Arctic

13. The area around Antarctica is referred to as the Southern or Antarctic

21. Continental Drift The movement of the seafloor caused by the continuous movement o the continents that rest on it.

22. The seafloor is constantly being replaced with new seafloor, therefore organisms have to adapt constantly.

27. Moving Continents Timeline of Moving Continents Early 1600’s Sir Frances Bacon Continents may have once been connected to each other. Proposed Gondwanaland- fusion of Southern Continents (S. America, Africa, India, Antarctica, and Australia). 19th Century Edward Suess 1915 Alfred Wegener One supercontinent= Pangaea. Forces of the Earth’s rotation separated the continents. Molten rock / Magma in the mantle moved by convection currents (heating and cooling of magma). 1960’s H.H. Hess

28. Pangaea

29. The man of Pangaea is Alfred Wegener

30. Evidence of Continental Drift 1. Continental plates fit together like a puzzle. 2. Distribution of Earthquakes -> occur in narrow zones that correspond to areas along ridges and trenches. Most active areas of crustal movement.

31. 3. Temperature of Sea Bottom-> highest temps at ridges. Temps decrease with distance from ridges. Why do you think that is????? Heating magma oozing out.

32. 4. Age of rock samples from seafloor. Youngest rock was found near ridges and older rocks were found further away. 5. Fossils collected on opposite coasts were similar.

33. 6. Coal deposits and other geological formations matched up on opposite sides of the Atlantic. 7. Sediment gets thicker and thicker as you move away from the ridges.

34. 8. Seafloor Spreading-> basalt magma from the mantle rises to create new ocean floor at mid-ocean ridges. On each side of the ridge, sea floor moves from the ridge towards the deep sea trenches, where it is subducted or sucked back into and recycled back into the mantle

35. 9. Magnetic evidence-> * 170 reversals in the past 76 million years (north / south polarity switched back and forth). Reverses directions. * Caused by fluctuations in the movement of material in iron-nickel outer core. * When rocks are in the molten stage they are free to move around and act like tiny little compasses pointing either north or south. * When the rocks cool they keep whatever their orientation is. There are literally stripes on the rocks that show the magnetic bands and they match up on either side of the mid ocean ridge= magnetic anomalies.

37. Continental Drift was not accepted at first because: Scientists thought that he did not have enough evidence to prove his theory.

38. Laurasia consisted of: Europe, Asia, and North America Gondwanaland- S. America, Africa, India, Antarctica, and Australia

40. The Forces that Drive Continental Movement HH Hess Convection currents- the way magma moves. Magma rises from the Earth’s core to the upper mantle because its less dense than the surrounding material. When it reaches the mantle it cools, becomes more dense, and sinks back into the core. This recycling causes changes in temperature called convection. Volcanoes form when the magma breaks through the Earth’s crust. Lines of volcanoes form underwater mountain ranges = midocean ridges When it cools, it forms new crust = oceanic basaltic crust

41. Rift Valley Where the Earth’s crust is splitting apart Narrow, steep sides, flat floor Looks like a ditch Created by tectonic activity High volcanic activity.

42. Tanzania’s Great Rift Valley

43. Fracture Zones- Linear regions of unusually irregular sea bottom. Almost like cracks in the crust

44. SUBDUCTION ZONES Regions where the old material / sinks down into the mantle and when it hits the magma of the mantle it liquefies and recycles itself through convection currents into the core.

45. Seafloor Spreading Oceanic plates are diverging from one another, the magma rises along a rift zone and spreads out at the surface building new sea floor. The age of the rocks increases as one moves away from the rift zone. The mid-oceanic ridge is the primary site for sea-floor spreading. Earthquakes and volcanoes are where seafloor spreading is occurring.

47. Theory of Plate Tectonics The lithosphere is viewed as a series of rigid plates that are separated by earthquake belts that are located around trenches, ridges, and faults.

48. Seven Major Plates are: 1._Pacific 2. North American 3. Eurasian 4. South American 5. African 6. Antarctic 7. Australian

49. Where plate boundaries move apart and new lithosphere is formed divergent plate boundaries occur. Where the old lithosphere is destroyed because the plates move toward each is called convergent plate boundaries. Where the plates move past each other = Faults.

50. Transform Fault Special kind of fault that is found in sections of the mid-ocean ridge. Each side is formed by a different plate and the plates scrape against each other