The rock cycle is the process by which rocks of one kind change into rocks of another kind. There are three main kinds of rocks: igneous rock, metamorphic rock, and sedimentary rock. Each of these rocks can change into the other kinds by one of these processes: cooling, melting, heat/pressure, weathering/erosion, and compacting/cementing (or squeezing tightly together). Two other substances also can become rocks and enter the rock cycle. They are magma which is liquid rock above or below ground, and sediment which is dust from crushed rock.
Igneous rock [change]
Igneous rock is hardened magma, which can happen above or below ground. It can melt into magma, erode into sediment, or be pressed tightly together to become metamorphic.
Metamorphic rock [change]
Metamorphic rock is pressurized igneous or sedimentary rock. It can erode into sediment or melt into magma. It formed under extreme pressure and temperature.
Sedimentary rock [change]
Sedimentary rock is compacted sediment which can come from any of the other rocks. It can erode back into sediment, or be pressurized into metamorphic rock.
These processes can occur in different orders, and the cycle goes on forever. Earth has several processes for changing rocks. Wind and water can create sediment from rocks, and movement of a tectonic plate creates heat and pressure which compacts rocks into rock crystals, and eventually rock.
- Earth Floor: Cycles. Exploring the Environment. Retrieved 2011-05-09.