 So this video talks a little bit more about motions in the mantle, and I made this for my physical sciences 152 course to kind of clear up some confusion and some gaps between the various resources we use. So let me start by talking a little bit about the mantle regions. Now depending on the textbook you look at it might mention two or three different regions of the mantle. There's the lithosphere which is the very very top of the mantle combined with the crust. The esthenosphere which is right below the lithosphere, and then the mesosphere. Now this particular diagram isn't necessarily to scale on everything, but the mesosphere is the larger section while the lithosphere is the thinner section. As we look at this diagram in a little bit enhanced view, and this diagram itself is on blackboard for my students, the lithosphere is listed as being a solid and a strong solid. So it's a very rigid solid that if you try to put pressure on it, it's going to break. And then for the mesosphere they just list it as solid, and for the esthenosphere it lists it as plastic, weak and deformable. Now where this really gets into play, and where some of the confusion comes in, is then when we talk about convection in the mantle. And this is an image from a different website, the Wikipedia, so it's one of the freely released ones here. And it shows that we have these convection currents in the mantle which sort of drags the esthenosphere, and this is responsible or the causing mechanism of plate tectonics. If you look up a definition of convection, it's the heat transfer through the motion of material, and the most common example is like a pot of boiling water, where you can actually watch the water roll in this rolling boil as you heat the bottom of it and that heat comes up through the edges. So this can cause a confusion here, because we've got something that's described as working like boiling water, but yet it was described as being a solid. So how does this work? And the thing is, is the mantle, both the mesosphere and the esthenosphere, are deformable solids. They don't flow like a liquid or a fluid would, but under a very great pressure, you're able to deform them and move them. So think of it more more similar, but not quite the same as if you've got a chunk of metal and a machine puts a great pressure on it, that metal will actually change shape. So there's great, great pressure and great temperature differences inside the earth that create great forces on the solid mantle that causes it to slowly, very, very slowly over time, have a motion to it. And this motion is then what causes the gradual creep of the esthenosphere causing the movement of that crust and the plate tectonics. So the diagrams and even the animations show this as being more like a rapid flow, but everything's sped up here. It doesn't flow like water or even flow like lava that you might have seen in videos of a volcano. Instead, these are solids, not liquids, that are moving only because of the very, very great pressure. I hope this helps clear things up for you. If not, continue to ask me questions to make sure that you have this concept and how it's different than the convection you might see in any other liquid or gas here on earth. We don't have the conditions here on the surface of the earth like is what's going on inside the earth.