Rocks are placed into three different types according to how they are formed. The rock cycle tells the story about how rocks change. The rock cycle changes igneous rocks and sedimentary rocks into metamorphic rocks. When rocks are under a really good deal of force, the heat will build up and this causes them to change. First of all, melting magma cools and gets crystallized into igneous rocks. Then the igneous rock gets weathered away by wind, ice, and glaciers and turn to sediment. Sediment breaks down and starts compacting and forming sedimentary rock. Later the sedimentary rock changes to metamorphic rock through heating and compression. Next metamorphic rock melts to magma and the rock cycle starts over again.