The process of rock formation involves three main types of rocks: igneous, sedimentary, and metamorphic.
1. **Igneous Rock Formation:** Created from the cooling and solidification of molten rock (magma or lava). If it cools beneath the surface, it forms intrusive igneous rocks (e.g., granite). If it cools on the surface, it forms extrusive igneous rocks (e.g., basalt).
2. **Sedimentary Rock Formation:** Formed from the accumulation of sediments, such as minerals, rock fragments, or organic material, which are compacted and cemented over time. Common examples include sandstone, limestone, and shale.
3. **Metamorphic Rock Formation:** Created when existing rocks (igneous, sedimentary, or other metamorphic rocks) are subjected to high heat and pressure, causing physical and chemical changes. Examples include schist and marble.
These processes occur over millions of years and are part of the rock cycle, where rocks continually change from one type to another.