Biostratigraphy of the Ordovician Nemagraptus gracilis Zone

  title={Biostratigraphy of the Ordovician Nemagraptus gracilis Zone},
  author={S. Finney and S. M. Bergstr{\"o}m},
  journal={Geological Society, London, Special Publications},
  pages={47 - 59}
Summary The middle Ordovician Nemagraptus gracilis Zone has long been used as a prominent, reliable correlation datum, having been recognized on every continent except Africa and Antarctica. However, there is some disagreement today on its definition and its boundaries. A re-examination of the original definition of the zone and evaluation of pertinent graptolite and conodont biostratigraphical data from key sections in Scotland, Wales, Scania, New York, Texas, Alabama and Australia indicate… Expand

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