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Seafloor Spreading
The document discusses the topography of the ocean floor and features obtained through technologies developed after World War I, including echo sounders and sonar. It describes various oceanic features, such as mid-ocean ridges, ocean trenches, and seamounts, and introduces the concept of seafloor spreading proposed by Harry Hess, which suggests the seafloor is younger than the continents. Evidence for seafloor spreading includes sediment thickness variations, the composition of oceanic crust, and patterns of submarine earthquakes.
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Seafloor Spreading
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- 2. Topographic Map Earth Whatdo you think the ocean floor would look like if we drain all the
- 3. The Ocean Floor Whatdo you think the ocean floor would look like if we drain all the seawater?
- 4. SEAFLOOR BATHYMETRY Many topographic featuresthat exist on the ocean basin are obtained after World War I using the following technologies:1 Echo Sounder 2 Side-scan Sonar 3 Satellite altimetry (Click blue textbox to show image) is the study of underwater depth of the ocean floor.
- 5. OCEAN BASIN Are theresults of tectonic forces and processes which are formed from volcanic rock that was released from fissures located at the mid-oceanic ridges.
- 6. 1) Pacific Ocean 4)Southern Ocean 3) Indian Ocean 5) Arctic Ocean 2) Atlantic Ocean Major Ocean Basins
- 7. OCEAN BASIN OCEAN BASINare lowareas of the seafloor
- 8. OCEAN BASIN TOPOGRAPHIC FEATURES 1 3 5 7 9 1 1 MID-OCEANIC RIDGE ABBYSALPLAINS OCEAN TRENCHES VOLCANOES SUBMARINE CANYONS 2 CONTINENTAL SLOPE 4 6 8 1 0 RIFT VALLEY SEAMOUNT OCEAN FLOOR CONTINENTAL RISE CONTINENTAL SHELF
- 9. OCEAN BASIN TOPOGRAPHIC FEATURES 1 3 5 7 9 1 1 MID-OCEANIC RIDGE ABBYSALPLAINS OCEAN TRENCHES VOLCANOES SUBMARINE CANYONS 2 CONTINENTAL SLOPE 4 6 8 1 0 RIFT VALLEY SEAMOUNT OCEAN FLOOR CONTINENTAL RISE CONTINENTAL SHELF Is normally found rising above the ocean floor at the center of ocean basins.
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- 11. The Mid-Atlantic ridgeis an underwater mountain range. It is part of the most extensive chain of mountains that wraps around the globe for more than 65,000 km. North American Plate Mid-Atlantic ridge
- 12. OCEAN BASIN TOPOGRAPHIC FEATURES 1 3 5 7 9 1 1 MID-OCEANIC RIDGE ABBYSALPLAINS OCEAN TRENCHES VOLCANOES SUBMARINE CANYONS 2 CONTINENTAL SLOPE 4 6 8 1 0 RIFT VALLEY SEAMOUNT OCEAN FLOOR CONTINENTAL RISE CONTINENTAL SHELF Found in the center of mid-oceanic ridge, between 30-50 km wide and 1,000-3,000 m deep.
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- 14. OCEAN BASIN TOPOGRAPHIC FEATURES 1 3 5 7 9 1 1 MID-OCEANIC RIDGE ABBYSALPLAINS OCEAN TRENCHES VOLCANOES SUBMARINE CANYONS 2 CONTINENTAL SLOPE 4 6 8 1 0 RIFT VALLEY SEAMOUNT OCEAN FLOOR CONTINENTAL RISE CONTINENTAL SHELF A small elevated landform that rises from the great depths of the ocean.
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- 16. OCEAN BASIN TOPOGRAPHIC FEATURES 1 3 5 7 9 1 1 MID-OCEANIC RIDGE ABBYSALPLAINS OCEAN TRENCHES VOLCANOES SUBMARINE CANYONS 2 CONTINENTAL SLOPE 4 6 8 1 0 RIFT VALLEY SEAMOUNT OCEAN FLOOR CONTINENTAL RISE CONTINENTAL SHELF A large submerged volcanic mountain rising from the ocean floor.
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- 18. OCEAN BASIN TOPOGRAPHIC FEATURES 1 3 5 7 9 1 1 MID-OCEANIC RIDGE ABBYSALPLAINS OCEAN TRENCHES VOLCANOES SUBMARINE CANYONS 2 CONTINENTAL SLOPE 4 6 8 1 0 RIFT VALLEY SEAMOUNT OCEAN FLOOR CONTINENTAL RISE CONTINENTAL SHELF Are long narrow, steep-sided depressions found on the ocean floor that contain the greatest depths.
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- 20. OCEAN BASIN TOPOGRAPHIC FEATURES 1 3 5 7 9 1 1 MID-OCEANIC RIDGE ABBYSALPLAINS OCEAN TRENCHES VOLCANOES SUBMARINE CANYONS 2 CONTINENTAL SLOPE 4 6 8 1 0 RIFT VALLEY SEAMOUNT OCEAN FLOOR CONTINENTAL RISE CONTINENTAL SHELF Can be found at the continental rise in water 4,000 to 6,000 meters deep.
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- 22. OCEAN BASIN TOPOGRAPHIC FEATURES 1 3 5 7 9 1 1 MID-OCEANIC RIDGE ABBYSALPLAINS OCEAN TRENCHES VOLCANOES SUBMARINE CANYONS 2 CONTINENTAL SLOPE 4 6 8 1 0 RIFT VALLEY SEAMOUNT OCEAN FLOOR CONTINENTAL RISE CONTINENTAL SHELF Numerous numbers of these topographical features can be found in ocean basin, approxi-mately 10,000.
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- 24. OCEAN BASIN TOPOGRAPHIC FEATURES 1 3 5 7 9 1 1 MID-OCEANIC RIDGE ABBYSALPLAINS OCEAN TRENCHES VOLCANOES SUBMARINE CANYONS 2 CONTINENTAL SLOPE 4 6 8 1 0 RIFT VALLEY SEAMOUNT OCEAN FLOOR CONTINENTAL RISE CONTINENTAL SHELF Can be found at the base of the continental slope. Its depth ranges from 2,000-5,000 me-ters deep.
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- 26. OCEAN BASIN TOPOGRAPHIC FEATURES 1 3 5 7 9 1 1 MID-OCEANIC RIDGE ABBYSALPLAINS OCEAN TRENCHES VOLCANOES SUBMARINE CANYONS 2 CONTINENTAL SLOPE 4 6 8 1 0 RIFT VALLEY SEAMOUNT OCEAN FLOOR CONTINENTAL RISE CONTINENTAL SHELF Are V-shaped canyons cut into the continental slope to a depth of up to 1200 meters.
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- 28. OCEAN BASIN TOPOGRAPHIC FEATURES 1 3 5 7 9 1 1 MID-OCEANIC RIDGE ABBYSALPLAINS OCEAN TRENCHES VOLCANOES SUBMARINE CANYONS 2 CONTINENTAL SLOPE 4 6 8 1 0 RIFT VALLEY SEAMOUNT OCEAN FLOOR CONTINENTAL RISE CONTINENTAL SHELF Is a shallow, gently sloping part of the continental crust with at an average depth of 130 m that borders the continent.
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- 30. OCEAN BASIN TOPOGRAPHIC FEATURES 1 3 5 7 9 1 1 MID-OCEANIC RIDGE ABBYSALPLAINS OCEAN TRENCHES VOLCANOES SUBMARINE CANYONS 2 CONTINENTAL SLOPE 4 6 8 1 0 RIFT VALLEY SEAMOUNT OCEAN FLOOR CONTINENTAL RISE CONTINENTAL SHELF Extends from the continental shelf at an average depth of 135 meters
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- 32. Which of thefollowing statements are TRUE? The seafloor is flat or bowl-shaped and the deepest portion is in the middle. The seafloor is the same age as the continents. The entire seafloor is the same age. The Earth is expanding; seafloor is created but never destroyed. Continents drift through the ocean and oceanic currents are responsible for
- 33. All of thefollowing statements are misconceptions. We’ll discuss them further… The seafloor is flat or bowl-shaped and the deepest portion is in the middle. The seafloor is the same age as the continents. The entire seafloor is the same age. The Earth is expanding; seafloor is created but never destroyed. Continents drift through the ocean and
- 34. RECALL the Evidencesof Continental Drift Theory Topographic Evidence, Fossil Correlation, Rock Formation and Paleoclimatic Evidence RECALL why many scientists rejected Alfred Wegener’s Continental Drift? Wegener could not conceive of an acceptable mechanism for moving the continents around.
- 35. SEAFLOOR SPREADING DEMONSTRATION ACTIVITY After theactivity, try answering the following questions: 1. How sea floor spreading happens? 2. How does the movement of the seafloor affects the continents? 3. Can seafloor spreading help prove continental drift theory? https://youtu.be/V0h8v2w3LGU?list=TLPQMzAwNDIwMjAzbEu4EGHGgA https://youtu.be/5eka88IOJ-I?list=TLPQMzAwNDIwMjAzbEu4EGHGgA
- 36. HARRY HESS THE THEORY OF SEAFLOOR SPREADING Inthe 1960’s Harry Hess, an American Geophysicist theorized that the seafloor is a hundred million years younger than the continents. He suggested that not only were the continents moving but the seafloor was also moving. He theorized that
- 37. SEAFLOOR SPREADINGSEAFLOO Rthe ground atthe bottom of the ocean SEAFLOOR SPREADINGthe process of creating new seafloor
- 38. Observations/Evidences that leadto the idea of SEAFLOOR SPREADING A. Distribution of seafloor topographic features – distribution of mid-ocean ridges and depth of the seafloor B. Sediment thickness – fine layer of sediment covering much of the seafloor becomes progressively thicker away from mid-ocean ridge axis; seafloor sediment not as thick as previously thought C. Composition of oceanic crust – consists primarily of basalt D. High heat flow along mid-ocean ridge axes – led scientists to speculate that magma is rising into the crust just below the mid-ocean ridge axis E. Distribution of submarine earthquakes – earthquakes do not occur randomly but define distinct belts (earthquake belts follow trenches, mid-oceanic ridges, transform faults).
- 39. HOW DO SEAFLOOR SPREADS? Moltenmaterial or magma from the Earth's mantle rises up because of mantle convection at ocean ridges, causing volcanic and seismic activity,
- 41. PALEOMAGNETIS M A proof thatsupports seafloor spreading. It tells how far from the poles rocks were when they were formed by looking at the angle of their
- 42. Want to LearnMore? Credits to: M.R. Dela Peña Edited by: R.N. Visit the following websites: • https://www.slideshare.net/AbbieMahinay • https://www.youtube.com/watch?v=fcqEnmIPui8 • https://www.youtube.com/watch?v=ZAAuY3l42qc • https://www.youtube.com/watch?v=-WgzkjPV5Sg
Editor's Notes
- #35 Point out that these arguments for continental drift can also be evidences to support seafloor spreading. The continents were once joined together but now separated. This implies that something had to be put between the continents for them to move apart. Then, relate Hess’ Seafloor Spearing.