The oracle of Delphi in Greece was the telephone psychic of ancient times: People came from all over Europe to call on the Pythia at Mount Parnassus to have their questions about the future answered. Her answers could determine when farmers planted their fields or when an empire declared war.

The Pythia, a role filled by different women from about 1400 B.C. to A.D. 381, was the medium through which the god Apollo spoke.

According to legend, Plutarch, a priest at the Temple of Apollo, attributed Pythia's prophetic powers to vapors. Other accounts suggested the vapors may have come from a chasm in the ground.

This traditional explanation, however, has failed to satisfy scientists. In 1927, French geologists surveyed the oracle's shrine and found no evidence of a chasm or rising gases. They dismissed the traditional explanation as a myth.

Their conclusion was aggregated by a modern misconception that vapors and gases could only be produced by volcanic activity.

Now, a four-year study of the area in the vicinity of the shrine is causing archaeologists and other authorities to revisit the notion that intoxicating fumes loosened the lips of the Pythia.

The study, reported in the August issue of Geology, reveals that two faults intersect directly below the Delphic temple. The study also found evidence of hallucinogenic gases rising from a nearby spring and preserved within the temple rock.

"Plutarch made the right observation," said Jelle De Boer, a geologist at Wesleyan University in Middletown, Connecticut, and co-author of the study. "Indeed, there were gases that came through the fractures."