The Rock Cycle is a group of changes. Igneous rock can change into sedimentary rock or into metamorphic rock. Sedimentary rock can change into metamorphic rock or into igneous rock. Metamorphic rock can change into igneous or sedimentary rock. Igneous rock forms when magma cools and makes crystals. Magma is a hot liquid made of melted minerals. The minerals can form crystals when they cool. Igneous rock can form underground, where the magma cools slowly. Or, igneous rock can form above ground, where the magma cools quickly. When it pours out on Earth's surface, magma is called lava. Yes, the same liquid rock matter that you see coming out of volcanoes. On Earth's surface, wind and water can break rock into pieces. They can also carry rock pieces to another place. Usually, the rock pieces, called sediments, drop from the wind or water to make a layer. The layer can be buried under other layers of sediments. After a long time the sediments can be cemented together to make sedimentary rock. In this way, igneous rock can become sedimentary rock. All rock can be heated. But where does the heat come from? Inside Earth there is heat from pressure (push your hands together very hard and feel the heat). There is heat from friction (rub your hands together and feel the heat). There is also heat from radioactive decay (the process that gives us nuclear power plants that make electricity). So, what does the heat do to the rock? It bakes the rock. Baked rock does not melt, but it does change. It forms crystals. If it has crystals already, it forms larger crystals. Because this rock changes, it is called metamorphic. Remember that a caterpillar changes to become a butterfly. That change is called metamorphosis. Metamorphosis can occur in rock when they are heated to 300 to 700 degrees Celsius. When Earth's tectonic plates move around, they produce heat. When they collide, they build mountains and metamorphose (met-ah-MORE-foes) the rock. The rock cycle continues. Mountains made of metamorphic rocks can be broken up and washed away by streams. New sediments from these mountains can make new sedimentary rock. The rock cycle never stops. Rock cycle time-consuming transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous Read in another language Watch this page Edit The rock cycle Magma fountain sprays liquid rock from deep underground The rock cycle is the process by which rocks of one kind change into rocks of another kind.[1] 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 physical processes: cooling, melting, heat, weathering/erosion, compacting (squeezing tightly together), cementing, and pressure. When heated deep under ground, rocks become magma (liquid rock). Above ground, it is called lava. Sediment, the particles from rock erosion and weathering, is the basis for sedimentary rock of the future.[2] Igneous rock is hardened magma, which can happen above or below ground.[1] It can melt into magma, erode into sediment, or be pressed tightly together to become metamorphic. Metamorphic rock is igneous or sedimentary rock that has been heated and squeezed.[1] It can erode into sediment or melt into magma. It is formed under extreme pressure and temperature deep inside mountain chains. Sedimentary rock is compacted sediment which can come from any of the other rocks,[1] plus remains of living things. 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 one tectonic plate against another creates enormous heat and pressure which affects rocks greatly.[3] Subduction converts all kinds into magma, which eventually rejoins the cycle as igneous rock. THE ROCK CYCLE IGNEOUS-SEDIMENTARY-METAMORPHIC Introduction The rock cycle consists of igneous rocks, sedimentary rocks and metamorphic rocks. These groups of rocks are constantly changing from one group into another. The rocks in each of these families are changing due to tectonic plate movement as crustal plates collide, move apart or slip past each other. 5Save Basalt rock that formed in the upper mantle, Myrna Martin Igneous rocks Igneous Rocks are a major group of rocks. All igneous rocks develop when molten rock cools and hardens. Find out about these igneous rocks in the links below that form when a volcano erupts: pyroclastic rocks, aa lava, welded tuff, ignimbrite, pyroclastic material, pahoehoe lava and basalt rocks. 5Save Seashell collection from shells collected on Pacific Ocean beaches, Myrna Martin Sedimentary rocks Sedimentary rocks form when older rocks weather. The pieces of older rock are carried down stream to form clastic rocks which include shale, mudstone and siltstone.  Sedimentary rocks found in the rock cycle are varied and include three major groups: clastic rocks, organic rocks and chemical rocks. You will find more information on clastic rocks, organic rocks, limestone caverns, salt domes and coal formation in the links below. 5Save Gneiss rocks are high-grade metamorphic rocks, Myrna Martin Metamorphic rocks Metamorphic rocks are the third group of rocks. Metamorphic rocks form when igneous, sedimentary and metamorphic rocks recrystallize without melting within the Earth. These rocks form intrusive rocks or plutonic rocks. Limestone rocks that recrystallize into metamorphic rocks form marble. Shale, a clastic rock, can recrystallize into gneiss a high-grade metamorphic rock. MORE ROCK CYCLE LINKS Pyroclastic Rocks Find out how pyroclastic rocks form during volcanic eruptions. Aa Lava Learn more about aa lava flows that occur on the Hawaiian Islands and the lava balls that often form on their surface. Welded Tuff Find out how welded tuff is produced during violent eruptions and by supervolcanoes. Intrusive Rocks Learn more about intrusive rocks that cool underground forming batholiths like the Sierra Nevada Mountains in California. Clastic Rocks Find out how bits and pieces of older rocks form shale, sandstone and conglomerate rocks. Pyroclastic Material This page gives all kinds of information about volcanic material that forms during volcanic eruptions. Organic Rocks Learn how animals extract calcite out of ocean water to form shells that are organic rocks. Limestone Caverns Learn how limestone caverns form and where you can visit some of them. Basalt Rocks Basalt rocks cover the floors of all the oceans, create cinder cones and form the largest volcanic mountains on Earth. Salt Domes Learn more about how salt domes form, what they are used for and how they are sometimes a key to find oil. Lava Caves Find out how pahoehoe lava flows form lava caves. Ignimbrite Learn more about ignimbrite that forms during large volcanic eruptions that produce pyroclastic flows. Coal Formation Find out how leaves falling into a swamp can turn into coal. Pahoehoe Lava Find out how pahoehoe lava forms in the Hawaiian Islands. Rock Cycle Learn more about igneous, sedimentary and metamorphic rocks and how they form. Kids Fun Science The links on our home page include information about volcanoes, science activities, plate tectonics, the rock cycle and much more. The Rock Cycle Click For Larger Image Rocks never completely disappear.  Igneous rocks may become metamorphic or sedimentary.  Sedimentary rocks become metamorphic and back into igneous.  Rocks are in an endless cycle called The Rock Cycle.  In the picture to the left you can see how different rocks will eventually become other rocks.