Igneous rocks are formed as a result of volcanic activity. When hot molten magma escapes from the mantle it cools and hardens. If it
reaches the surface as lava, it cools and solidifies quickly, whereas the magma inside the crust cools more slowly.
Metamorphic rock
Burial, high temperatures and pressures
Sedimentary rocks
Sedimentary rocks are formed from particles of other rocks, as well as dead plants and animals. These sediments are deposited on sea and lake beds as well as on land. Layers of this material build up over time and are compressed and cemented, creating solid rock.
Compression and cementation
Sedimentary rock
Metamorphic rocks
Metamorphic rocks are formed from rocks that already exist. They form when igneous or sedimentary rocks are changed into new, harder rocks by great heat or pressure or sometimes both.
(i) List two ways in which rocks differ from one another. (ii) List three different categories of rocks. (iii) Which rock type has different layers? (iv) Briefly describe how igneous rocks form. (v) Briefly describe how sedimentary rocks form. (vi) Briefly describe how metamorphic rocks form.
/ I can list the ways in which rocks differ from each other. / I know the three rock groups and I can explain how they are formed.
