Ancient Greek and Roman authors stated that the Apollo’s sacred oracle at Delphi in central Greece was located at the site of unusual geological features an phenomena: a chasm or fissure in the rock; an emission of sweet-smelling vapor or gas; and a sacred spring.  The priestess who pronounced the oracles, known as the Pythia, sat on a tall tripod above the fissure where she could inhale the vapor, thus triggering a prophetic trance in which she could serve as a medium for the prophetic oracles of the god Apollo.  So great was the influence of the woman’s words that scarcely a colony was founded or a war undertaken in Greece for over a millennium without the sanction of the Delphic Oracle.  Famous figures from Oedipus and Agamemnon to Alexander the Great and various Roman emperors consulted the shrine.

During the 20^th century, most scholars adopted a skeptical attitude towards the ancient traditions about Delphi, denying that there had ever been a fissure or a gaseous emission in the crypt of the temple.  However, in 1995 an interdisciplinary team was created to study not only the archaeology of Delphi, but also the evidence from geology, chemistry, and toxicology that related to the oracle.  The results of the research vindicated the ancient sources.  Our team has gone on to study Greek oracle sites elsewhere in the Aegean and Asia Minor, where we have found similar geological features.