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10 Science Seafloor Spreading theory.pptx
- 1. Most Essential LearningCompetency Trace how the seafloor spreading theory was develop by the scientist. Identify the different evidences that support the seafloor spreading Explain how the evidences support the seafloor spreading Appreciate the significance of this evidences in the theory of plate tectonics ● Enumerate the lines of evidence that support plate movement
- 2. Alfred Wegener Despite theevidences presented in his theory, his idea that the continents were once joined together was not accepted by the scientific society until 1960s.
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- 12. Purpose of theSeafloor studies during WWII To understand the topography of the sea floor To find hiding places for both allied and enemy submarines
- 13. enabled scientists tomake better observations and gather new information about the ocean floor.
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- 15. MID-OCEAN RIDGES A systemof ridges or mountains in the seafloor like those found in the continents Located: Atlantic Ocean Cleft size: 32km- 48km long Depth: 1.6 km
- 16. Harry Hammond Hess RobertS. Dietz
- 18. The processof seafloor spreading allowed the creation of new bodies of water.
- 20. one of themost active sites of seafloor spreading, with more than 14 centimeters every year
- 21. What happens tothe ocean floor at deep ocean trenches? Continental Plate Oceanic Plate
- 22. As thenew seafloor is formed at the mid-ocean ridge, the old seafloor farthest from the ridge is destroyed at the subduction zone.
- 23. The rateof formation of a new seafloor is not always as fast as the destruction of the old seafloor at the subduction zone. Getting smaller Getting wider
- 24. ON is FASTER THAN SEAFLOOR SPREADIN G, theocean _ _ _ _ _ _ _ _ SPREADIN G is GREATER THANK the SUBDUCTI ON, then the ocean gets _ _ _ _ _
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- 27. 1. Rocks areyounger at the mid-ocean ridge. 2. Rocks far from the mid-ocean ridge are older. 3. Sediments are thinner at the ridge. 4. Rocks at the ocean floor are younger than those at the continents.
- 28. It states thatcontinents moved through unmoving oceans and that larger and sturdier continents broke through the ocean crust. It shows that the ocean is the actual site of tectonic activity.
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- 30. -Magnetic evidence inrocks. C REVERSA L
- 31. Seafloor spreading wasstrngthened with discovery that the magnetic rocks near the ridge follow a pattern aside from the fact that rocks near the ridge are remarkably younger than those farther from the ridge.
- 32. The Earth’s magneticfield is a DIPOLE, North and South Pole. Magnetic Compass Direction of the earth Show earth magnetic field
- 33. MAGNETIC REVERSAL Simple Experiment 1.Using a magnet rub the needle to the magnet 20 times. 2. Slowly place the plastic bottle cap at the middle and place the needle on top of it. 3. Observe what happen. 4. How does the needle work?
- 34. The needle became magnetizedafter rubbing the magnet against it, and once magnetized, it will have a north and south pole, exactly like other magnets. Needle The plastic bottle cap on the water’s surface was able to move freely after it was submerged. Plastic bottle cap The magnetized needle then force the plastic cap to spin around until the needle’s North and South poles aligned with the Earth’s N and
- 35. • Also calledmagnetic ‘fip” of the Earth • It happens when the geographic North Pole is transformed into a South Magnetic Pole or vice versa. Magnetic Reversal
- 36. • The occurrenceof magnetic reversals can be explained through the magnetic patterns in magnetic rocks, esp.those found in the ocean floor.. Magnetic Reversal • When lave solidifies, iron bearing mineral crystallize. • The minerals behave like tiny compasses and align with the Earth’s magnetic field.
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- 38. Over the last10 million years, there has been an average of 4-5 reversals per milion years MAGNETIC REVERSAL