Rock cycle — Science definition
The continuous, looping set of processes — cooling, weathering and erosion, lithification, metamorphism, and melting — that recycle Earth's materials among igneous, sedimentary, and metamorphic rock.
Where it is taught
- The Rock Cycle — Rocks, Landscapes & Water, Earth & Space Science, Grade 9
In use
The rock cycle is the name for that endless recycling — the set of processes that shuffle the same Earth material back and forth among the three great rock families: igneous, sedimentary, and metamorphic.
The Rock Cycle
Questions using rock cycle
Problem 1
Answer and explanation
Because any rock type can change into any other rock type depending on which process acts on it next, there's no fixed starting or ending point, so a loop with many crossing arrows shows all the possible paths.
Problem 2
- Sedimentary to metamorphic to magma to igneous
- Igneous only to sedimentary
- Metamorphic only to igneous
- Sedimentary cannot change
Answer and explanation
Sedimentary to metamorphic to magma to igneous
Any rock type can become any other given the right conditions; the cycle has no fixed one-way path.
Problem 3
- Earth's internal heat and the Sun
- the Moon
- the oceans alone
- lightning
Answer and explanation
Earth's internal heat and the Sun
Internal heat drives melting and uplift; solar energy drives weathering, erosion and transport.
Problem 4
Answer and explanation
Because there is no fixed start or end and no single path: a sedimentary rock may be metamorphosed, melted and cooled as igneous, or weathered straight back into sediment. Any type can become any other depending on the conditions it meets, so a cycle with multiple routes represents the processes more honestly than a line would.
Response criteria
- State a scientifically accurate conclusion.
- Show the data, mechanism, or calculation that supports it.
- Include units, conditions, or limits where relevant.