The movement of tectonic plates across the Earth’s Molten magma that rises at a mid-ocean ridge is very surface is thought to be caused by a process called hot and heats the rocks around it. As the At a subduction boundary, one plate is ‘slab pull’. asthenosphere and lithosphere at the ridge are denser and heavier than the other plate. The denser, heated, they expand and rise higher than the heavier plate begins to subduct beneath the plate that surrounding sea floor. This produces a slope down is less dense. The edge of the subducting plate is and away from the ridge. Gravity then causes this much colder and heavier than the mantle, so it older, denser material to slide away from the ridge. continues to sink, pulling the rest of the plate along This is called might be better called ‘ridge push’ but with it. The force that the sinking edge of the plate gravitational sliding exerts on the rest of the plate is called slab pull. Ancient lava flows on land record remnant magnetism. Slab pull is presently considered to be a much Iron particles are aligned in the direction of the stronger factor than ridge push or mantle convection in magnetic North Pole. These record differences over driving plate movements. time that show that the magnetic field has Earth’s completely reversed on a number of occasions.
The movement of tectonic plates across the Earth’s surface is thought to be caused by a process called ‘slab pull’. At a subduction boundary, one plate is denser and heavier than the other plate. The denser, heavier plate begins to subduct beneath the plate that is less dense. The edge of the subducting plate is much colder and heavier than the mantle, so it continues to sink, pulling the rest of the plate along with it. The force that the sinking edge of the plate exerts on the rest of the plate is called slab pull. Molten magma that rises at a mid-ocean ridge is very hot and heats the rocks around it. As the asthenosphere and lithosphere at the ridge are heated, they expand and rise higher than the surrounding sea floor. This produces a slope down and away from the ridge. Gravity then causes this older, denser material to slide away from the ridge. This is called ‘ridge push’ but might be better called gravitational sliding Slab pull is presently considered to be a much stronger factor than ridge push or mantle convection in driving plate movements. Ancient lava flows on land record remnant magnetism. Iron particles are aligned in the direction of the magnetic North Pole. These record differences over time that show that the Earth’s magnetic field has completely reversed on a number of occasions.
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