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Ocean Floor Topography and Features
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- 2. SOund Navigation AndRanging
- 3. Distance = RateX Time Depth = ½ time X Velocity Speed of Sound in Ocean = 1,524 m/s EXAMPLE PROBLEM: What is the ocean depth if the signal time of return is 5.4 seconds. D = ? t = 5.4 seconds v = 1,524 m/sec. Depth = ½(5.4sec.) x 1,524 m/sec. Depth = 2.7 sec. x 1,524 m/sec. Depth = 4,114.8 meters
- 4. Distance = RateX Time Depth = ½ time X Velocity Speed of Sound in Ocean = 1,524 m/s SAMPLE PROBLEM: What is the ocean depth if the signal time of return is 7.2 seconds. D = ? t = 7.2 sec. v = 1,524 m/sec. Depth = ½(7.2sec.) x 1,524 m/sec. Depth = 3.6 sec. x 1,524 m/sec. Depth = 5,486.4 meters
- 10. What would theworld look like with no oceans? Atlantic Ocean Basin Pacific Ocean Basin
- 12. Continental Margin • Thezone of the ocean floor that separates the thin ocean crust from the thick continental crust. Active Margin • Shorter continental shelf near the boundaries of plates where more geologic activity tends to take place. • US WEST COAST Passive Margin • Longer continental shelf further away from active plate boundaries. • US EAST COAST
- 13. Continental Shelf • Slopingarea that borders each continent. • Its width varies from just a few kilometers to as much as 1,300 km. Continental Slope • Steady incline marks the continental slope. • Pacific Ocean Slopes are steeper than Atlantic Ocean Slopes. Submarine Canyons • Submarine canyons are steep-sided valleys cut into the sea floor of the continental slope. • Can extending well onto the continental shelf.
- 14. Abyssal Plain • Thicklayer of sediment, formed by the sunken remains of dead organisms from the surface. • Cover vast, flat plains. Abyssal Hills • An abyssal hill is a small hill that rises from the floor of an abyssal plain. • Covering more than 30% of the ocean floors. • Have relatively sharply defined edges and climb to heights of no more than a few hundred meters.
- 15. Mid Ocean Ridge •Consists of many peaks along both sides of a central valley. • Chain of undersea volcanic mountains that run around the world.
- 17. Fracture Zones • Afracture zone is a linear oceanic feature—often hundreds, even thousands of kilometers long— resulting from the action of offset mid-ocean ridge axis segments – transform plate boundaries. • They are a consequence of plate tectonics. Hydrothermal Vents • Water seeps down through cracks, gets heated by the mantle, then emerges as steam (black smokers). • Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart, ocean basins, and hotspots.
- 18. Trench • Canyons created whena dense plate subducts (sinks) below a less dense plate. • The Mariana Trench in the Pacific is 11 KM deep
- 21. Volcanic Island • Volcanoeson the ocean floor erupt, they can create mountains whose peaks break the surface of the ocean. • As lava cools, the islands form. Seamounts • Mountains whose peaks do not break the surface of the ocean water. Guyot • A Volcanic Island that has been eroded away by wave action resulting in a flat top. • As the ocean floor moves away from the oceanic ridges, the sea floor gradually sinks, submerging the flattened peaks undersea.
- 24. atoll • An atollis a ring-shaped coral reef, island. • An atoll surrounds a body of water called a lagoon. • Atolls develop with underwater volcanoes, called seamounts. Tiny sea animals called corals begin to build a reef around the island. These corals create a hard exoskeleton of limestone (calcium carbonate). Billions of these limestone exoskeletons are the reef. • This coral reef, called a fringing reef, surrounds the island just below the ocean surface. • Over millions of years, the volcanic island erodes and sinks under the ocean leaving behind the atoll.