Here's a breakdown of what lies beneath the plates:
* Lithosphere: This is the rigid outermost layer of Earth, consisting of the crust and the uppermost part of the mantle. This is what the tectonic plates are made of.
* Asthenosphere: This is a partially molten layer of the upper mantle, located beneath the lithosphere. It's "plastic" in the sense that it can flow over very long timescales. The lithospheric plates "float" on the asthenosphere.
* Mesosphere: This is the lower mantle, extending down to the Earth's core. It's solid but can still deform under extreme pressure.
The movement of the tectonic plates is driven by convection currents within the mantle. Hotter, less dense material rises, while cooler, denser material sinks, creating a cycle of movement. This movement causes the plates to move, collide, and separate, resulting in geological phenomena like earthquakes, volcanoes, and mountain ranges.
So, while the plates themselves are made of lithosphere, they "float" on a layer of partially molten rock called the asthenosphere, which is part of the Earth's mantle.
