more stuff than the core, though, so distributing the heat means that the overall temperature is a bit lower, and since it's not in the center of everything, there's less pressure so it flows around like a thick liquid. The crust moves around on the outside of this, causing tectonic plate movement. As the plates move and run into each other, in some places one plate slides over another. This is called a subduction zone. The plate that slides under melts as it pushes into the hot mantle. It melts relatively slowly and tends to trap some of the liquid stuff (called magma when it's inside the planet) between the two plates, creating a magma chamber. The plate movement builds pressure in the magma chamber, and the only place the pressure can vent is through cracks in the crust created by earthquakes and such. When the magma vents out of the crust and reaches the surface it is then refered to as lava, and the lava leaking out is what creates one type of volcano known as a "shield volcano" as well as another type known as a "lava dome." There is another type of volcaic mountain known as a "composive volcano," but that's not lava and you specifically asked about lava. I could go on forever here, in fact I'm afraid I almost have. If you have any more questions, please feel free to contact me directly via email or IM: darren_hepp@yahoo.com Look it this way, take a metal