Rock cycle
The rock cycle is a continuing process, beginning as rocks are pushed up by tectonic forces, and eroded by wind and rain. The eroded rocks travel by wind or moving water until they are crushed, settling into layers. Additional eroded rocks may bury these layers until heat and pressure change the underlying layers to metamorphic rock. More eroded rocks may squeeze and press the layers into sedimentary rocks. Rocks can also be sunk down into the lower layers of the earth by plate tectonic processes. Buried rocks may also melt and turn into igneous rocks. Metamorphic, sedimentary, and igneous rocks may then be pushed up by tectonic forces, starting the rock cycle again.