WJEC Geology GL2 Geological Processes — Unit Papers & Mark Schemes

GL2 rewards candidates who can connect geological processes to the rocks and structures they produce. When asked about a specific rock type, trace backwards through the process chain: a porphyritic andesite, for example, indicates two-stage cooling — slow crystallisation at depth (producing phenocrysts) followed by rapid eruption and quenching (producing a fine-grained groundmass) — at a convergent plate margin. Sedimentary environment questions test your ability to read the clues preserved in rocks. Grain size, sorting, roundness, cross-bedding geometry, and fossil content each reveal aspects of the depositional environment. Practise interpreting vertical sedimentary logs, identifying coarsening-upward sequences (e.g., prograding deltas) and fining-upward sequences (e.g., meandering river point bars). Structural geology questions demand precise use of terminology. Know the geometric elements of folds (axial plane, hinge line, limbs, plunge) and faults (hanging wall, footwall, hade, throw, heave). When describing a fault, specify its type (normal, reverse, thrust, strike-slip) and the stress regime that produced it.