era, rocks, period, strata, age, time, times, formations, forms, basement, formation, sediments, fossils, ages, periods, deposits, types, corals, series, fauna, beds, fishes, limestones, floor, stratigraphy, palaeogeography, plants, geology, epoch, crinoids, flora, sandstones, rock, genus, seas, shales, type, insects, echinoids, mesozoic, algae, fish, epochs, slates, events, massif, genera, schists, crinoid, evolution, limestone, bedrock, animals, amalgamation, granites, shells, brachiopods, magmatism, spirifer, extinctions, terranes, plateau, sea, ferns, chorus, basins, belts, seeds, palaeomagnetism, reefs, sequence, deposit, ridge, forests, complex, sedimentation, biostratigraphy, aera, orogeny, faunas, eras, sequences, sulphide, ocean, tectonics, platform, basin, deformation, volcanism

late, early, lower, upper, later, older, post, pre, middle, latest, younger, earlier, proterozoic, folded, earliest, mid, eminently, characteristic, type, lowest, marine, lowermost, fossiliferous, horizontal, thick, eroded, shallow, undisturbed