1. The Ocean Floor Chapter 14 Earth Science Ms. Weigel

2. Seafloor Maps Discovery Video Field Trip 1.Describe how sonar technology can help scientist map an area of sea floor 2.Does sonar technology provide realistic measurements for the entire ocean floor? Why or why not?

3. THE VAST WORLD OCEAN 14.1

4. The Blue Planet 1.Nearly 71 percent of Earth’s surface is covered by the global ocean. 2.The oceans have only been an area of study since the late 1800’s 3.Oceanography is a science that draws on the methods and knowledge of geology, chemistry, physics and biology to study all aspects of the world ocean.

5. Geography of the Oceans 1.Earth is about 510 million square kilometers- approx. 360 million sq km is represented by oceans and smaller seas such as the Mediterranean Sea and the Caribbean Sea. 2.Continents and islands comprise the remaining 29 % 3.The world ocean can be divided into four main ocean basins- the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, and the Artic Ocean

6. Pacific Ocean Largest Ocean Coves more than half of the ocean surface World deepest ocean- avg. depth of 3940 meters Atlantic Ocean Half the size of the Pacific, not quite as deep Relatively narrow ocean The Atlantic and Pacific are bounded to the east and west by continents.

7. Indian Ocean Slightly smaller than the Atlantic, but same average depth Located almost entirely in the southern hemisphere Arctic Ocean 7 percent of the size of the Pacific Little more than one-quarter as deep as the rest of the oceans

8. Mapping the Ocean Floor Activity Use Figure 3 on page 396 of your text book 1.In which ocean basins are most of the oceanic trenches located 2.Which ocean basins contain oceanic ridges? 3.What is the major undersea geological feature in the Atlantic? 4.What kind of geological feature is part of the Hawaiian islands?

9. Mapping the Ocean Floor 1.If all the water were drained from the ocean basins, a variety of features would be seen including chains of volcanoes, tall mountain ranges, trenches, and large submarine plateaus 2.The topography of the ocean floor is as diverse as that of continents.

10. Mapping the Ocean Floor 3. Bathymetry is the measurement of ocean depths and the charting of the shape or topography of the ocean floor. 4. Today’s technology- particularly sonar, satellites, and submersibles- allows scientists to study the ocean floor in a more efficient and precise manner than every before.

11. Sonar 1.In the 1920’s a technological breakthrough occurred with sonar, a type of electronic depth- sounding equipment 2.Sonar is an acronym for sound navigation and ranging. 3.Depth can be calculated from the speed of sound waves in water-about 1500m per sec- and the time required for the energy pulse to reach the ocean floor and return. 4.In the last few decades, sonar has been used to map the ocean floor

12. Sonar Methods: Determine depth of ocean floor and obtains profiles

13. Satellites 1.Measuring the ocean surface from space is another breakthrough 2.Looking at waves, tides, currents and atmospheric effects, scientists discovered the ocean surface is not perfectly flat. 3.Satellites are able to measure things not visible to human eye 4.This is done by bouncing microwaves off the ocean surface.

14. Satellite Method- they can be used to measure sea-surface height.

15. Submersibles 1.A submersible is a small underwater craft used for deep-sea research. 2.They are used to collect data about areas of ocean that were previously unreachable by humans 3.Can record video and photos 4.Can collect water samples and sediment 5.First submersible in 1934

16. Assessment Page 400 1-7

17. THE OCEAN FLOOR 14.2

18. There are three major ocean floor region: 1.The continental margins 2.The ocean basin floor 3.Mid-Ocean Ridge

19. Continental Margins 1.The zone of transition between a continent and the adjacent ocean basin is known as the continental margin. 2.In the Atlantic Ocean, thick layers of undisturbed sediment cover the continental margin. 3.This region has very little volcanic or earthquake activity. 4.In the Pacific Ocean, oceanic crust is plunging beneath continental crust resulting in a narrow continental margin that experience both volcanic activity and earthquakes

20. Continental Shelf 1.The continental shelf is the gently sloping submerged surfce extending from the shoreline. 2.Continental shelves contain important mineral deposits, large reservoirs of oil and natural gas, and huge sand and gravel deposits.

21. Continental Slope 1.Marking the seaward edge of the continental shelf is the continental slope 2.Deep, steep-sided valleys known as submarine canyons are cut into the continental slope. 3.Turbidity currents are occasional movements of dense, sediment-rich water down the slope. 4.These currents are an important mechanism of sediment transport in the ocean, they erode submarine canyons and deposit sediments on the deep ocean floor.

22. Continental Rise 1.Where trenches do not exist, the steep slope merges into a more gradual incline known as the continental rise.

23. Ocean Basin Floor 1.Between the continental margin and mid- ocean ridge lies the ocean basin floor. 2.The size of this region is almost 30 percent of Earth’s surface

24. Deep-Ocean Trenches 1.Trenches form at sites of plate convergence where one moving plate descends beneath another and plunges back into the mantle. 2.Earthquakes and volcanic activity are associated with these regions.

25. Abyssal Plains 1.Abyssal plains are deep, extremely flat features. 2.The sediments that make up abyssal plains are carried there by turbidity currents or deposited as a result of suspended sediments settling.

26. Seamounts and Guyots 1.The submerged volcanic peaks that dot the ocean floor are called seamounts. 2.They are volcanoes that have not reached the ocean surface. 3.Once underwater volcanoes reach the surface, they form islands.

27. Mid-Ocean Ridges 1.The mid-ocean ridge is found near the center of most ocean basins. 2.This system is the longest topographic feature on Earth’s surface.

28. Seafloor spreading 1.Seafloor spreading occurs at divergent plate boundaries where two lithospheric plates are moving apart. 2.New ocean floor is formed at mid-ocean ridges as magma rises between the divergent plates and cools.

29. Hydrothermal Vents 1.These vents form along mid-ocean ridges. 2.These zones where mineral-rich water, heated by the hot, newly-formed oceanic crust, escapes through cracks in oceanic crust into surrounding water.