Why plates float

However, convection also drives plate tectonics. Picture this scenario: when you cook noodles in a pot of water, you create convection cells. The noodles move upward in the middle of the pot where the temperature is higher, and then downward on the edges of the pan where the temperature is lower. Such convection cells exist inside the Earth's mantle.

One difference is that the mantle is not liquid; rather, the solid rocks are so hot that they can slowly flow. Hot, less dense rock material goes toward the crust whereas relatively denser, less hot material goes toward the core.

At certain times and places, hot, upflowing rock material in these convection cells weakens continental crust to create rifts and eventually new ocean basins. The East-African Rift, for instance, is the result of such a convection cell breaking up the African plate.

Convection cells were responsible for the breaking up of supercontinents many times in Earth's history. Skip to main content. Climate Sea Levels Why will sea level rise not be the same everywhere?

How can we date corals? Geology and Tectonics Geology How do we know the age of the seafloor? Why is the seafloor so recent and the continental crust so old? Where do we find the oldest continental rocks and the oldest seafloor? What are the different types of rocks? What is a fossil and what are they used for? The continental and oceanic crusts sit on a thick layer of solid rock known as the mantle. While there is a layer of liquid rock in the earth known as the outer core, this layer is about km below earth's surface and is separated from the surface by the thick solid mantle.

The tectonic plates do not slowly drift over time because they are floating on a layer of liquid rock. They drift because they are sitting on a layer of solid rock the upper mantle or "asthenosphere" that is weak and ductile enough that it can flow very slowly under heat convection, somewhat like a liquid. If there is not a giant sea of magma under the continents, where does lava come from? The molten lava that spews out of volcanoes is created locally right under the volcano rather than being released from a global sea of magma.

Evidence from previous studies hints at a similar structure beneath the coast of Norway and another off Costa Rica. Additional reporting by Elizabeth Finkel. Originally published by Cosmos as What tectonic plates float on. Cosmos is published by The Royal Institution of Australia, a charity dedicated to connecting people with the world of science. Financial contributions, however big or small, help us provide access to trusted science information at a time when the world needs it most.

Please support us by making a donation or purchasing a subscription today. New research shows a lubricating jelly layer beneath the tectonic plates that allows them to slide. At the base of the plate they found a 10 km thick jelly-like channel, the lithosphere asthenosphere boundary LAB , which decouples it from the underlying asthenosphere.

Additional reporting by Elizabeth Finkel Originally published by Cosmos as What tectonic plates float on. More from:. Plate boundaries migrate over time and it is unlikely that convection cells within the mantle would migrate with them. The migration of plate boundaries across the surface of the Earth means that they are not firmly fixed into the underlying convective motions of the mantle - from our analysis of real plate motions mantle convection is more likely to be related to the location of hot spots and mantle plumes.

So what, then, drives the plates? An answer to this question may lie in an analysis of the forces acting on plates, both on their undersides and at their boundaries. As you work through this course you will need various resources to help you complete some of the activities. Making the decision to study can be a big step, which is why you'll want a trusted University.

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