February 2009 Geology and GSA Today media highlights

Boulder, CO, USA - GEOLOGY includes three papers about Mars; continuation of the "jelly sandwich" versus "crème brûlée" debate; support for the Snowball Earth hypothesis; what nine-million-year-old tooth enamel says about vegetation in an ancient sub-Himalayan ecosystem; anthropogenic lead in the Tyrrhenian Sea; evidence for a prehistoric South Pacific tsunami; a multicentennial megadrought in medieval Europe; and a newly discovered fossil turtle in the Canadian Arctic. GSA Today's science article proposes a new method for classifying Quaternary glacial deposits.

Highlights are provided below. Representatives of the media may obtain complementary copies of articles by contacting Christa Stratton at Please discuss articles of interest with the authors before publishing stories on their work, and please make reference to GEOLOGY or GSA TODAY in articles published. Contact Christa Stratton for additional information or assistance.

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Tropical sea temperatures in the high-latitude South Pacific during the Eocene
Christopher J. Hollis et al., GNS Science, P.O. Box 30368, Lower Hutt 5040, New Zealand. Pages 99-102.

Hollis et al. provide evidence for a tropical climate in the high-latitude southwest Pacific in Eocene time. The early Eocene, around 50 million years ago, has been long recognized as a time of pronounced global warming. In New Zealand, warm climate conditions were inferred for this time period from a wide range of fossil evidence but, until now, the degree of warmth was uncertain. Hollis et al. used three independent geochemical methods for extracting sea temperatures from the sedimentary rock record and determined that surface waters exceeded 30 degrees Celsius, and water at the sea floor hovered around 20 degrees Celsius, during what is inferred to have been a 2-3-million-year episode of greenhouse gas-induced global warming. These temperatures are at the extreme end of modern tropical water masses (annual sea surface temperatures of 25-30 degrees Celsius). Tropical temperatures at this high-latitude location (55 degrees south) present a huge challenge for climate modelers. Even under extreme greenhouse conditions of greater than 2000 parts per million of carbon dioxide, modeled temperatures for Eocene era New Zealand do not exceed 20 degrees Celsius. Anomalously warm conditions have also been reported for early Eocene records from high-latitude regions in the Northern Hemisphere. It now seems likely that some as yet unknown heat transport mechanism comes into play during times of extreme global warmth.

Lateral trends in carbon isotope ratios reveal a Miocene vegetation gradient in the Siwaliks of Pakistan
Michele E. Morgan et al., Peabody Museum, Harvard University, Cambridge, Massachusetts 02138, USA. Pages 103-106.