Key Earth Science Links
Late Ordovician Mass Extinction
University of Southern California, Department of Earth Sciences. Nice outline of the Late Ordovician extinction, with pictures and graphs of the marine invertebrates that were affected and paleogeographic maps showing where glaciers were.
Enchanted Learning software. This site is a summary of mass extinctions, but includes a graph on the first page that shows that the Late Ordovician extinction was the greatest extinction of invertebrates.
Deep Time-Ordovician Period. PBS.org. Summary of life (with links) in the Ordovician with a short summary of the extinction at the end of the Ordovician.
Stable Isotopes. What can they tell us about oceans, atmospheres, and mass extinction? Jim Marshall, University of Liverpool. Summary of how carbon isotope changes accompany the major mass extinctions, using the end-Ordovician mass extinction as an example.
National Academies Press. Online version of technical paper by W. Berry and others, University of California, Berkeley, which summarizes data and impacts of continental glaciation and deglaciation on the Late Ordovician mass extinction. A shorter summary of these ideas was published at the Catastrophic Events Conference.
See also these articles for technical summaries:
Sheehan, P.M., 2001, The Late Ordovician mass extinction: Annual Reviews of Eearth and Planetary Sciences, v. 29, p. 331-364.
Some key references (technical articles)
- Berry, W.B.N., and Boucot, J., 1973, Glacio-eustatic control of Late Ordovician-Early Silurian platform sedimentation and faunal changes: Geological Society of America Bulletin, v. 84, p. 275-284.
- Berry, W.B.N., Quinby-Hunt, MS., and Wilde, P., 1995, Impact of Late Ordovician glaciation-deglaciation on marine life, in Panel on Effects of Past Global Change on Life, National Research Council (eds.), Effects of Past Global Change on Life: Washington, D.C., National Academy Press, Commission on Geosciences, Environment, and Resources, p. 34-46. Examines the influence of Late Ordovician glaciations on extinction of marine life (specifically graptolites), including a 50 m drop in sea level, isotopic evidence for cooling ocean surface waters, and changes in deep ocean circulation caused by colder glacial waters.
- Brenchley, P.J., Carden, G.F., and Marshall, J.D., 1995, Environmental changes associated with the “first strike” of the Late Ordovician mass extinction: Modern Geology, v. 20, p. 69-72.
- Brenchley, P.J., and others, 2003, High-resolution stable isotope stratigraphy of Upper Ordovician sequences: Constraints on the timing of bioevents and environmental changes associated with mass extinctions and glaciations: Geological Society of America Bulletin, v. 115, no. 1, p. 89-104. Identifies two phases of Late Ordovician mass extinction and correlates them to periods of rapid climate change associated with the buildup and melting of Gondwana glaciers.
- Marshall, J.D., and Middleton, P.D., 1990, Changes in marine isotopic composition and the late Ordovician glaciations: Journal of the Geological Society, v. 147, p. 1-4. Examines isotropic data from Late Ordovician brachiopod shells, which indicate simultaneous shifts in carbon and oxygen isotopes consistent with the onset of Late Ordovician glaciations and rapid global cooling.
- Sheehan, P.M., 2001, The Late Ordovician mass extinction: Annual Reviews of Earth and Planetary Sciences, v. 29, p. 331-364. Correlates glaciation with two pulses of extinction, and infers that the first pulse was caused by sea level fall and draining epicontinental seas. The second pulse is hypothesized to have been caused by sea-level rise. Glaciation also caused changes in climate and ocean circulation that influenced extinction.
- Sutcliffe, O.E., and others, 2000, Calibrating the late Ordovician glaciations and mass extinctions by the eccentricity cycles of Earth’s orbit: Geology, v. 28, no. 11, p. 967-970. Infers that Ordovician glaciations were controlled by the eccentricity cycle similar to the Pleistocene glaciations. If controlled by eccentricity, than the duration of the Late Ordovician extinction can be inferred from Late Ordovician glaciation cycles.