Knowra Historical geology Historical geology Historical geology reconstructs Earth’s past from rocks, fossils, and other geological evidence, establishing the sequence and causes of changes in the planet and its life.
Stratigraphy : The study of rock layers and their relationships, used to interpret geological history. Superposition and layer correlations establish the relative order of events.
Law of superposition : The principle that, in an undisturbed sequence, lower sedimentary layers are older than layers above them. It establishes relative ages within a sequence of strata.
Paleogeography : The reconstruction of the geographic arrangement of land, seas, and other features in the geological past. It maps how continental positions and ancient environments changed through time.
Great Oxidation Event : A major rise in atmospheric oxygen beginning about 2.4 billion years ago. Ancient rocks preserve evidence of this fundamental change in Earth’s atmosphere.
Physical geology : The study of the materials, structures, and processes that shape Earth. It emphasizes how geological processes operate, while historical geology emphasizes their sequence through time.
Geologic time scale : A chronological framework dividing Earth’s history into eons, eras, periods, epochs, and ages. It organizes reconstructed events into a shared timeline.
Principle of faunal succession : The principle that fossil organisms appear and disappear in a recognizable chronological order. Distinctive fossil assemblages help correlate and relatively date rock layers.
Paleoclimatology : The study of climates that existed before modern instrumental records. Geological archives reveal long-term climate patterns and abrupt shifts.
Cambrian explosion : A geologically rapid diversification of many animal groups beginning around 539 million years ago. Fossil succession reveals a major transition in the history of complex animal life.
Actualism : The methodological principle that past geological processes are explained using physical laws and mechanisms that remain valid today. It clarifies how present-day observations can inform explanations without assuming unchanged rates or conditions.
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