Rocks and the Rock Cycle
Rocks are igneous, sedimentary or metamorphic and cycle between types.
About this topic
Rocks are classified by how they form. Igneous rocks form from cooled magma or lava (granite, basalt); sedimentary rocks form from compacted and cemented sediments (sandstone, limestone) and often contain fossils; metamorphic rocks form when heat and pressure change existing rocks (marble from limestone, slate from shale).
The rock cycle shows how each type can change into another through melting, weathering, erosion, deposition, burial and uplift over millions of years. No rock is permanent.
A single mineral grain can pass through all three states. Imagine granite formed from slowly cooling magma deep underground, which is uplifted and weathered into sand, buried and cemented into sandstone, then baked and squeezed into quartzite, and finally melted again to start over. Crystal size in igneous rocks shows cooling speed: large crystals mean slow cooling underground (granite), while tiny crystals mean fast cooling at the surface (basalt).
Sedimentary layers record environments and contain fossils, and they hold most of the oil, coal and groundwater we use. Metamorphic rocks may show foliation, banded layers formed under directed pressure, as in gneiss. Rocks give materials for buildings, such as marble, slate and granite. Geologists read them like pages to reconstruct how landscapes formed. A common misconception is that the cycle follows a fixed order; any rock can go to any other state, and many paths are possible. Also, metamorphic rock does not melt; if it melts, it becomes magma and the rock is igneous when it cools.
Key ideas
- Igneous from cooled magma
- Sedimentary from compacted sediments
- Metamorphic from heat and pressure
Quick check
Use cases: where Rocks and the Rock Cycle helps
- Homework: review the key idea behind Rocks and the Rock Cycle before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Rocks and the Rock Cycle without notes.
- Visual learning: play with the interactive lab to see how Rocks and the Rock Cycle changes when you adjust its inputs.
- Teaching a friend: explain Rocks and the Rock Cycle in your own words, then compare your version with the key ideas.
Earth science helps with weather forecasts, natural hazards, energy and climate planning.
Frequently asked questions
What is Rocks and the Rock Cycle?
Rocks are igneous, sedimentary or metamorphic and cycle between types.
What will I learn in Rocks and the Rock Cycle?
Igneous from cooled magma. Sedimentary from compacted sediments. Metamorphic from heat and pressure.
Is Rocks and the Rock Cycle part of Earth & Space?
Yes. It is one of 60 Earth & Space topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Rocks and the Rock Cycle lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Rocks and the Rock Cycle?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.