What are igneous, sedimentary and metamorphic rocks?
Rocks are made up of different minerals and form the Earth’s crust (outer layer). Different combinations of minerals form rocks; minerals are made of elements.
There are 3 different types of rocks; igneous, sedimentary and metamorphic.
Igneous rock is formed when magma or lava from volcanoes cools. Examples include basalt and granite. Most igneous rock is very hard. Some of the most spectacular rock formations on our planet are made of igneous rock; in Britain we see granite shapes called tors in south-western locations like Bodmin Moor, Dartmoor and Land’s End.
Sedimentary rocks are formed over millions of years when sediments (tiny pieces of rocks and animal skeletons) are pressed together at the bottom of seas and rivers. Examples include sandstone, coal and chalk. Some sedimentary rocks contain fossils (bones or shells of living things that were buried long ago and have turned to stone).
Metamorphic rocks are formed when other rocks are changed due to heat or pressure. Examples include slate and marble. Metamorphic rocks are very hard but can be damaged by acids like acid rain or even lemon juice.
Fossils are created when plants or animals are trapped within rocks. Soils are made from rocks and organic matter.