What happens to the fluid at the top of the asthenosphere? (subject: science)

Sitting on top of the outer core, we find the mantle. this layer is by far the thickest layer of earth, about 1,800 miles thick! it also makes up about 85% of earth's volume. like the core, the mantle contains mostly iron, but in the form of silicate rocks. you might be surprised to learn that this rock actually moves like a fluid, similar to how silly putty moves. if you poke silly putty hard, it acts like a solid, but if you slowly pull it apart, it acts like a liquid. we call this ability of rock to move without breaking plasticity.the mantle can also be divided into two portions, the upper mantle and the lower mantle. the lower mantle is completely solid because, like the solid inner core of earth, the pressure is just too great for it to melt and flow. the upper mantle is also known as the asthenosphere, which flows as convection currents. convection occurs in all fluids and is the rising of warm particles and sinking of cool particles. so, as the material in the upper mantle warms, it rises straight up, and as it rises, it cools and then sinks back down.