* Igneous rocks: These form from cooling magma or lava.
* Intrusive igneous rocks (like granite and gabbro) form when magma cools slowly underground, giving large crystals time to grow. These are commonly found deep in the Earth's crust.
* Extrusive igneous rocks (like basalt and rhyolite) form when lava cools on the surface. While they can be found deep underground, they are more commonly found at the surface.
* Metamorphic rocks: These form when existing rocks (igneous, sedimentary, or other metamorphic rocks) are changed by heat and pressure deep within the Earth. Examples include marble (from limestone), slate (from shale), and gneiss (from granite).
* Sedimentary rocks: These form from the accumulation and cementation of sediments, often at the surface. While some sedimentary rocks can be buried deep underground, they are less common than igneous and metamorphic rocks at depth.
In summary: While all types of rocks can be found underground, igneous and metamorphic rocks are most common at significant depths.
