You may have noticed that there are many kinds of rocks, from the soft sandy rocks that form the cliffs at Scripps beach to the hard rocks that form the mountains to the East of San Diego. Geologists have developed a way of classifying the various rocks and understand fairly well where they come from and where they go. Thus rocks are always changing form and are redistributted as part of a giant cycle of renewal. This cycle is called the Rock Cycle .
Volcanoes are places where magma erupts as lava or ash .
Sediment is the stuff that is transported by wind, water or ice to a site of deposition. Many plants and animals precipate hard parts made for example of calcite and leave organic sediments behind. Limestone is an example of an organic sediment. The range of temperatures for metamophism is 150C up to the melting temperature. Metamorphism causes growth of new minerals, rotation or deformation of mineral grains, and recrystallization of minerals.