Peter Ward's 'Gorgon': a great darkness

December 21, 2003|By John R. Alden | John R. Alden,Special to the Sun

Gorgon: Paleontology, Obsession, and the Greatest Catastrophe in Earth's History, by Peter Ward. Viking. 288 pages. $27.95.

What, in the view of paleontologists, was the greatest catastrophe in Earth's history? Measured by the number of species that disappeared forever in a brief span of time, it wasn't the asteroid impact that wiped out the dinosaurs at the end of the Cretaceous some 63 million years ago -- it was the Permian Extinction that happened almost 200 million years earlier.

There have been five great extinctions in the last half billion years -- biological cataclysms during which more than half of the species living on the earth died off within a short -- geologically speaking -- time. (By those terms, of course, we are probably living during a sixth great extinction, precipitated by humankind's 10,000-year march from hunting and gathering to the biological domination of the planet.) Yet of those great extinctions, scientists only agree on the cause of the one that terminated the Cretaceous.

Did the Permian end with the kind of cosmic bang that wiped out the dinosaurs? Was that extinction a result of dramatic changes in oceanic chemistry or atmospheric composition caused by vast belches of noxious carbon dioxide (from volcanic eruptions) or methane (from deep sea waters and ocean bottom deposits)? Or was it due, as scientists long believed, to gradual climatic change brought about by global warming or continental drift?

Gorgon, named after the most dramatic denizen of the late Permian bestiary, is geologist and paleontologist Peter Ward's account of his adventures searching for the cause of the Permian extinction.

Ward, a professor at the University of Washington, is an accomplished writer as well as a scientist active in the research described in his book. His informed and informative book will delight anyone curious about the process and progress of modern scientific investigation into the earth's biological history.

Ward's story is rich with descriptions of South Africa, where he was hunting for fossils in the Karoo highlands, and of the people he worked with on various expeditions. There is a lot about the process of fieldwork, about the beauty of the Karoo, and about the difficulties and rewards of working in this challenging environment. And scattered throughout the narrative are clear accounts of the questions that Ward and his colleagues want to address and the way the data they are laboring to collect may reveal some answers.

The work carried out by Ward and his associates reduced the time frame for the Permian extinction from a few million to less than 100,000 years. It added important detail to the paleontological picture of late Permian and early Triassic life in the Karoo. But it didn't tie down what caused the Permian extinction.

When Ward finished writing, he thought the most plausible explanation for the Permian extinction was a massive release of carbon dioxide or methane into the earth's atmosphere. Last month, however, a group of geologists working in Antarctica published a paper saying they'd identified evidence of a meteoritic impact in the Permian / Triassic boundary stratum. In explaining the Permian extinction, as with so many other questions in science, there is much that remains to be done.

John R. Alden is an archaeologist interested in the origin and evolution of complex societies. His most recent fieldwork in a difficult but rewarding environment was in highland Iran, where he hopes to return next spring.

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