Science
How does the rock cycle work?
The rock cycle is the slow, continuous process by which rocks change from one type to another over millions of years. Heat, pressure, melting, weathering, and sediment build-up keep recycling Earth's rock between igneous, sedimentary, and metamorphic forms.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how the rock cycle works.
Step by step
- 1Igneous rock forms when molten magma or lava cools and hardens.
- 2Weathering and erosion break rock into sediment, which compacts into sedimentary rock.
- 3Heat and pressure deep underground transform rock into metamorphic rock.
- 4Buried deep enough, rock melts back into magma, and the cycle begins again.
- 5Plate tectonics drives much of this by moving and burying rock.
Frequently asked questions
- What are the three main types of rock?
- Igneous (cooled from molten rock), sedimentary (compacted sediment), and metamorphic (changed by heat and pressure). The rock cycle converts between them.
- How long does the rock cycle take?
- Usually millions of years. It's far too slow to watch, but the evidence is everywhere in the layers and structures of Earth's rocks.
- What powers the rock cycle?
- Earth's internal heat (driving melting and plate movement) and surface forces like water, wind, and ice (driving weathering and erosion).