 And when the mantle gets very shallow, it melts. When it melts, it makes basalt. So we have basalt. We start to convey your belt. That's part of what's driving plate tectonics, is that making new basalt continuously is what they call ridge push. Not only is it up higher than the surrounding area, so the gravity is helping move the slabs off, but we're also making new material continuously. So the greatest volcanic activity on Earth is the continuous formation of basalts underwater at these ridges continuously for the last at least four billion years we've been doing that. And that's part of the fact that we're saying that we're not creating or destroying anything. We're reshuffling. So we're moving stuff around. We melt the mantle because of decompression. And then it cools, and we have crossed, and then it comes back down and melts again. So the energy that it takes to melt, which is an endothermic reaction. We have to put energy in there. However, the opposite is the exothermic reaction is when they come to the other end, they release a lot of that energy so that we're transferring energy around. We have that original thermal energy, but then we're moving it around and we're switching between phases. So now the two biggest thermal effects on Earth are this really hot core and this cooling mantle. And so that there's a geothermal gradient as we go down so that the places that we see heat coming out of the planet are where plumes arise at mid-ocean ridges and at the volcanic arcs where the magnets are coming out. So this is an interesting interplay between formation across, destruction across, building continents via that arc magnetism. When I say arc magnetism, I mean above the seduction zone where the water comes out into the mantle, flux is melted, then that rises up. So we get chains of them and they're shaped like an arc because we're on a spherical planet. And so the slab isn't like we draw it. We draw the slab going down like this, but it's not because we're on a sphere. So it's going down like that, which means that it's an arc you had shaped with the volcanoes that it makes. So if you look at the Japan arc, it's shaped like that and all the arcs on Earth are shaped like that. And the magnet that forms from the dehydration of the slab causing mantle melting, it doesn't know what's about it. So it can rise up and come up like Japan in the ocean and make an oceanic arc, or it can be like the Andes and come up through continental crust and actually help make a big mountain range. So we find the mountain ranges at the boundaries of the plates. And so either if it's ocean ocean or if it's continent, that's where we make the mountain ranges. So the mountain ranges are important in this whole process of reshuffling things around and moving them around.