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By MARLAN DOWNEY

If the Data Doesn't Fit, You Must Admit (It)

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Perhaps a review of the past may make us better geologists in the future.

"Studies on Origin of Petroleum; Occurrence of Hydrocarbons in Recent Sediments," by P.V. Smith, Esso, appeared in the AAPG BULLETIN, Vol. 38, 1954.

" ... It seems plausible to suggest that petroleum is being formed in the present era and that the crude product is nature's composite of the hydrocarbon remains of many forms of marine life."

This was a very thorough piece of work, documenting that hydrocarbon molecules from recently living cells are abundantly dispersed in many muddy sediments.

Analytical techniques of the time suggested a similarity between these hydrocarbons and crude oils. Many geologists and geochemists seized on this work to pronounce that the problem of the origin of petroleum had been solved, and the only remaining questions involved collection and migration of these recent hydrocarbons to traps.

Unfortunately, this was a major misdirection. Within a decade, gas chromatographic analytical techniques determined that these hydrocarbon molecules from recent organisms differed fundamentally from the hydrocarbons characterizing all crude oils. The hydrocarbons in crude oil were shown to be identical to those produced by the thermal cracking of organic matter buried deeply in the earth.

The concept that crude oil is a composite of hydrocarbon debris from recently living organisms seemed to fit the available evidence, but ... it was wrong.

Perhaps it is a good reminder to us that it is easy to create a hypothesis that fits the data -- but fitting the available data doesn't mean that the hypothesis is true.