For many many years no underlying fissure or possible source of intoxicants was found. Experts had concluded that the vapors were mythical, like much about Delphi.
Now a geologist, an archaeologist, a chemist and a toxicologist teamed up to produce a wealth of evidence confirming that that reason the ancient Greeks gave for the oracle's inspiration, vapors rising from the temple's floor, actually exist.
It turns out that the underlying rocks under Delphi are composed of oily limestone fractured by two faults crossing directly under the ruined temple.
These fisures create a path by which petrochemical fumes could rise to the surface to induce visions.
Specifically the scientists found ethylene — a sweet-smelling gas once used as an anesthetic. In light doses, it produces feelings of euphoria.
"What we set out to do was simple: to see if there was geological truth to the testimony of Plutarch and the others," said Dr. Jelle Zeilinga de Boer, a Wesleyan University geologist involved with the research.
The team's work was described in 2001 in Geology, the magazine of the Geological Society of America, and at the annual meeting in January 2002 of the Archaeological Institute of America. There was also an article in the April 2002 issue of Clinical Toxicology.
source: New York Times