There are three different types of rock.
igneous rocks are made from cooled magma which mas molten and solified. where the rock reaches the surface we sometimes get a volcano. the rocks contain crystals wich are made from various minerals. the crystals are arranged randomly.
sedimentary rocks are formed from layers of sediment laid down in lakes or seas over millions of years. the particles are then cemented togeather by crystals of salt. sometimes the remains of long dead plants and animals are found in the rock. these are called fossils. scientists study the fossil type to work out the age of the rock. in general, the deeper the rock, the older it is.
metamorphic rocks are formed by changes to other types of rock. they can be caused by pressure or heat effects, or both togeather. the changes take a long time. metamorphic rocks can contain tiny crystals and may also have minerals.
sedimentary rocks are formed from layers of sediment laid down in lakes or seas over millions of years. the particles are then cemented togeather by crystals of salt. sometimes the remains of long dead plants and animals are found in the rock. these are called fossils. scientists study the fossil type to work out the age of the rock. in general, the deeper the rock, the older it is.
metamorphic rocks are formed by changes to other types of rock. they can be caused by pressure or heat effects, or both togeather. the changes take a long time. metamorphic rocks can contain tiny crystals and may also have minerals.
No comments:
Post a Comment