Metamorphosed sedimentary rocks are the dominant rock types in the park, but some igneous rocks also occur. Sedimentary rocks form through a cycle of erosion and deposition mostly in water. The eroded materials include cobbles, pebbles, sand, silt, and clay, or the accumulations of shells from ancient sea animals. Igneous rocks solidify from melted rock or lava. Rocks become metamorphosed when they are subjected to heat and pressure, usually related to mountain building. Metamorphosed sandstone, siltstone, and shale, are most common in the park. However, metamorphosed limestone and dolomite are found in the Anakeesta Formation and unmetamorphosed limestone and dolomite are found on the floor of Cades Cove, below the Great Smoky fault.