WJEC Geology GL4 Geological Record — Unit Papers & Mark Schemes

Know the geological time scale confidently. You should be able to place the Eons (Hadean, Archaean, Proterozoic, Phanerozoic), Eras, and key Periods in correct sequence with approximate dates. Associate each Period with its characteristic life forms: Cambrian (trilobites, first shelled fauna), Carboniferous (coal swamp forests, amphibians), Jurassic (dinosaurs, ammonites), and so on. Correlation questions test your ability to match strata between separate locations using biostratigraphy (zone fossils with short time ranges and wide geographic distributions), lithostratigraphy (matching distinctive rock units), and chronostratigraphy (absolute dating). Know the criteria for a good zone fossil: short stratigraphic range, wide geographic distribution, easily identifiable, and abundant. Palaeogeographic reconstruction questions ask you to infer ancient environments from rock and fossil evidence. When given a stratigraphic column, identify transgression (deepening-upward sequences) and regression (shallowing-upward sequences), and explain how changes in sea level, tectonic activity, or climate produced the observed succession.