Other mass extinctions

Neal Monks (UK) The extinctions at the Cretaceous-Tertiary (K/T) boundary make up what is probably the most famous geological event in popular culture. This is the point when the great reptiles that characterise the Mesozoic went extinct. Alongside the dinosaurs, the giant marine reptiles died out too, as did the pterosaurs, and a whole host of marine invertebrates, including the ammonites and belemnites. What happened? Some geologists argue the climate changed over a period of a million years or more, thanks to the massive volcanism that created the Deccan Traps in India. Others maintain that the K/T extinctions happened suddenly, pointing to evidence of a collision between the Earth and an asteroid. Perhaps there wasn’t a single cause, but rather a variety of factors: volcanism, climate change, asteroid impact, underlying changes in flora and fauna, and perhaps even variation in the output of the Sun and resulting weather patterns. That life on Earth can be wiped out this way is the stuff of disaster movies as much as TV documentaries. However, what comes as a surprise to many people is that there wasn’t just one mass extinction at the K/T boundary, but a whole series of them that can be observed throughout the fossil record. One of them, the Permo-Triassic extinctions, appear to have been even more catastrophic than the K/T extinctions, and at least three other extinction events are comparable in scale. In between these five big extinctions were lots of smaller extinctions that aren’t well studied, but had … Read More

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Geology and fossil fauna of the South Ferriby foreshore

John P Green (UK) The large working quarry at South Ferriby, North Lincolnshire (SE991204) is a well known and productive source of Late Jurassic and Cretaceous fossils, exposing beds from the Upper Oxfordian stage, Upper Jurassic (Ampthill clay, Ringsteadia psuedocordata zone) to the Terebratulina lata zone of the Turonian stage (Welton Chalk Formation, Upper Cretaceous). Research on the stratigraphy and palaeontology of the site has been carried out by many authors, and a generalised section detailing the overall stratigraphy and macrofossil occurrences was published by the local amateur geologist, Dr Felix Whitham (1992). However, in recent years, access to the quarry for geologists has been relatively curtailed due to health and safety concerns. In light of this, my research at South Ferriby has shifted to the nearby geological exposures on the easily accessible foreshore, on the southern banks of the Humber Estuary. Fig. 1. South Ferriby foreshore, looking east. In general terms, the beds exposed on the South Ferriby foreshore tilt eastward, exposing the older (Jurassic) rocks to the west and the younger (Cretaceous) rocks to the east. The exposures are largely wave-cut platforms, accessible only at low tide, and are often covered with sand and estuarine sediments, as well as a large variety of erratic rocks and fossils. Especially prominent among the latter are carboniferous corals and limestones, Cretaceous flints, the Jurassic oyster, Gryphaea, and specimens of the Cretaceous (Late Campanian) belemnite, Belemnitella mucronata, most likely derived from chalk of this age that floors the North Sea. The low … Read More

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