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16 Αυγ 2018 · Students will analyze a magnetic polarity map, calculate seafloor spreading rates, and present their findings. They will learn that magnetic reversals are caused by changes in Earth's core and prove seafloor spreading by magnetic patterns in ocean floor rocks.
Seafloor Spreading Activity. Most basalt magmas contain abundant molten iron. As magma starts to harden into rock, iron-rich minerals solidify first. Their crystals are pulled into alignment by the Earth’s magnetic field, just like a compass needle is pulled towards magnetic north.
Seafloor spreading, or seafloor spread, is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. History of study.
29 Νοε 2023 · Seafloor spreading is a geologic process in which tectonic plates —large slabs of Earth's lithosphere —split apart from each other. Seafloor spreading and other tectonic activity processes are the result of mantle convection. Mantle convection is the slow, churning motion of Earth’s mantle.
Periodic reversals of the Earth’s magnetic field are shown by the remanent magnetisation of rocks of the sea bed, which have been used to demonstrate sea floor spreading. Following up the activity: • Study maps of magnetic anomalies as measured over the oceanic ridges and look for the symmetrical patterns.
At spreading centres, this crust is separated into parallel bands of rock by successive waves of emergent magma. When Earth's geomagnetic field undergoes a reversal, the change in polarity is recorded in the magma, which contributes to the alternating pattern of magnetic striping on the seafloor. (more)
29 Μαρ 2004 · Interactive Animation of Seafloor Spreading and Magnetic Field Reversals. Earth's magnetic field reverses itself from time to time; North becomes South and South becomes North. Lava that cools and becomes rock at a given time in Earth's history stores a record of our planet's magnetic polarity at the time of the rock's formation.
