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A Smoking Gun for an Ancient Methane Discharge

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Science  19 Nov 1999:
Vol. 286, Issue 5444, pp. 1465
DOI: 10.1126/science.286.5444.1465

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Paleoceanographers are closing in on a possible cause for the evolutionary watershed 55 million years ago that brought modern mammals into global dominance: a vast belch of climate-changing methane from under the sea floor. Proposed less than 5 years ago, the "methane burp" hypothesis gets its most direct support yet on page 1531 of this issue of Science. Paleoceanographers have discovered a sequence of sediment layers buried half a kilometer below the sea floor off Florida, which records the exact sequence of deep-sea changes--including vast submarine landslides--predicted by the scenario.