* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Sea-Floor spreading
Maxwell's equations wikipedia , lookup
Magnetosphere of Jupiter wikipedia , lookup
Van Allen radiation belt wikipedia , lookup
Magnetosphere of Saturn wikipedia , lookup
Electromagnetism wikipedia , lookup
Mathematical descriptions of the electromagnetic field wikipedia , lookup
Superconducting magnet wikipedia , lookup
Geomagnetic storm wikipedia , lookup
Lorentz force wikipedia , lookup
Edward Sabine wikipedia , lookup
Electromagnetic field wikipedia , lookup
Giant magnetoresistance wikipedia , lookup
Magnetometer wikipedia , lookup
Magnetic stripe card wikipedia , lookup
Magnetic monopole wikipedia , lookup
Neutron magnetic moment wikipedia , lookup
Magnetic nanoparticles wikipedia , lookup
Electromagnet wikipedia , lookup
Earth's magnetic field wikipedia , lookup
Magnetotactic bacteria wikipedia , lookup
Force between magnets wikipedia , lookup
Multiferroics wikipedia , lookup
Magnetoreception wikipedia , lookup
Magnetochemistry wikipedia , lookup
Ferromagnetism wikipedia , lookup
Magnetotellurics wikipedia , lookup
Lesson Objective • Explain how sea-floor spreading provides a way for continents to move. • Describe how new oceanic lithosphere forms at mid-ocean ridges. • Explain how magnetic reversals provide evidence for sea-floor spreading. Sea-Floor Spreading • supports the continental drift hypothesis • Sea-Floor spreading process by which new oceanic lithosphere forms as magma rises toward the surface and solidifies. Sea-Floor Spreading • Mid-Ocean Ridges Mid-ocean ridges are underwater mountain chains that run through Earth’s ocean basins. • Mid-ocean ridges are located where sea-floor spreading takes place. Sea-Floor Spreading • Moving Sea-floor collides into continental crust • Subduction occurs when a denser (oceanic) crust moves under a less dense (continental) crust Subduction occurs at a “convergent” boundary Sea-Floor Spreading • Subduction form “trenches” • Trench • hemispheric-long, narrow depressions of the sea floor. • deepest parts of the ocean floor! Some not measurable • important natural boundaries formed between two lithospheric plates. Subduction form “trenches” • A trench marks the position at which the denser slab begins to descend beneath another lithospheric slab (less dense). • 3 to 4 km (1.9 to 2.5 mi) below the level of the surrounding oceanic floor. • The deepest ocean depth to be sounded is Mariana Trench at a depth of 10,911 m (35,798 ft) below sea level. (higher than Mt. Everest) Sea-Floor Spreading • What: mid-oceanic ridges, trenches, guyots • Where: oceanic crust • When: 1957-1963 • How??? What data or evidence? MAGNETIC FIELDS A field of attraction or repulsion to another substance based on its composition MAGNETIC FIELDS • Outer core of the Earth The molten iron flows creates an electric current (flow of electrons) & a magnetic field that surrounds the planet. • The magnetic field created in the center of the planet makes your compass point north • Protects the Earth from solar winds. MAGNETIC FIELDS MAGNETIC FIELDS Magnetic Stripes Alignment pattern of magnetic grains in the sea-floor crust that change over time based on the Polar direction (N v S) Every 100 K years the magnetic poles change direction (magnetic reversal) Magnetic Strips along the Mid-Ocean Ridge The older crust moves outward. Dates are confirmed by the Magnetic Reversal of the crust. Animation link How do… • Magnetic Stripes relate to Sea-floor Spreading? • What is Geomagnetic Reversal? • Magnetic Anomalies relate to Continental Drift? What is… • Paleomagnetism the Earth’s record of magnetic fields in rocks, clay or bricks, by direction and intensity “Guyot” (gee-oot) • Tabletop mountain, under the sea that stretches for miles • Cooled, flattened seafloor as it moves away from the mid-ocean ridge • Today, see old plateaus in mid West (UT, NM, CO) Mt. Roraima Earth Today Earth tomorrow RESOURCES • http://images.yourdictionary.com/pangaea • Magnetic Reversal animation • http://www.sciencebuddies.org/science-fairprojects/project_scientific_method.shtml • http://www.sciencedaily.com/articles/o/oceani c_trench.htm • www.appstate.edu/~marshallst/GLY1101/.../3 -Continental_Drift.pptx