Igneous: Formed directly from the cooling and crystallization of magma/lava. The original rock.
Sedimentary: Formed by weathering, erosion, deposition, and lithification (compaction) of any other rock type.
Metamorphic: Formed when existing rock is subjected to extreme Heat and Pressure deep underground.
Tags
GeologyRock TypesWeatheringMagma
Transformational Processes
Melting & Cooling
Any rock (Sedimentary, Metamorphic, or even older Igneous) dragged deep into the mantle by subduction will melt into magma. When that magma erupts or cools underground, it crystallizes into new Igneous Rock.
Result: IGNEOUS ROCK
AP Exam Tip
Only Sedimentary Rock contains fossils. Heat and pressure (Metamorphic) or melting (Igneous) destroys any biological remnants. Also, remember that the cycle is non-linear—any rock can become any other rock!