Friday, August 19, 2005

Scrambling among the rocks

The sandstone cliffs at the end of the Dingle Peninsula are quick to yield trilobite fossils. I have several fine specimens on the ledge above our fireplace. In 1839, fossils were collected here by Richard Griffith, the first important cartographer of Irish geology. He sent them off to London to be examined by expert paleontologists. The verdict came back: The fossils were of Silurian age, which we now know to be about 420 million years ago.

Farther east, near the limestone Vale of Tralee, the rocks of the Dingle Peninsula were recognized as Devonian, younger than the Silurian. What then of the strata between, the so-called Dingle beds? Were they Silurian or Devonian?

The question might now seem to be of little consequence, but at the time it was momentous, for reasons that were personal and social as well as scientific. The dispute about the age of the Dingle rocks was a skirmish in a larger war of ideas and personalities, the so-called Great Devonian Controversy.

The chief antagonists were, on the one hand, Henry De la Beche, the director of the Geological Survey of Britain, and, on the other, Roderick Murchison and Adam Sedgwick of the Geological Society of London. At issue was the proper interpretation of those sedimentary formations that (as we now know) were laid down between 300 and 400 million years ago.

Careers and reputations turned on the outcome of each skirmish in the war. The status and prestige of scientific institutions waxed and waned with the rise and fall of hypotheses. Egos swelled and shrank with each new coloring of the geologic maps.

It short, it was a classic conflict of scientific ideas, fought with all the gusto and resolve that a few years later would mark the battles over Darwin's theory of evolution by natural selection.

In the end, the issue was not resolved by the exercise of institutional power or the weight of egos, but by the evidence of the rocks themselves.

It is the great strength of the scientific enterprise that it can contain flawed personalities, rampant egos, hidden agendas, imperfect motivations, and still reach consensus. The bottom line is the evidence of nature. Not piecemeal evidence -- a rock here, a fossil there -- but the vast, systematic assembly of data that speaks with more authority than any individual or institution.