Earth & space science · Grades 9–12
Rocks, plate boundaries and geological timescales · revision notes
Igneous, sedimentary and metamorphic rocks describe formation processes. Material can move among these categories through several possible pathways.
Key ideas and conditions
Rock cycle
Igneous, sedimentary and metamorphic rocks describe formation processes. Material can move among these categories through several possible pathways.
Plates
Lithospheric plates move relative to one another. Boundary types influence deformation, volcanism and earthquake patterns but do not make every location identical.
Time
Relative dating orders events under geological principles; numerical ages require suitable measurements and models. Geological rates can vary over time.
Evidence
Combine structures, fossils where appropriate, mineral evidence and dating constraints. A single sample rarely describes an entire geological history.
Explain without looking
- Why is the rock cycle not a single compulsory circular sequence for every rock?
- Which evidence may help reconstruct deformation history?
Further reading and review references
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