| A | B |
|---|
| origin | how they were formed |
| three main groups of rocks | sedimentary, igneous, metamorphic |
| Sedimentary rocks | formed by the cementing together of sediments that form in water and show flat layers |
| igneous rocks | rocks that are made from melted liquid rocks that have cooled and hardened |
| crystallization or solidification | hardening process |
| magma | melted rock material |
| lava | melted rock |
| volcanic glass | igneous rocks that cool quickly that there is no time for the crystals to form and this gives the rock a glassy texture |
| metamorphic rocks | form when rocks that already exist are changed by heat, pressure or chemicals into different rock |
| metamorphism of rock causes | distortion, increased density, different chemical composition |
| distortion | twisting and bending of the rock |
| increased density | high pressure squeezes the atoms closer together raising the density |
| different chemical composition | material may be added or removed during the changing process or the rearrangement or the atoms may form new materials |
| rock cycle | tells us any rock can be changed into any other type of rock |
