Ancient tradition linked the Delphic oracle in Greece to specific geologica
l phenomena, including a fissure in the bedrock, intoxicating gaseous emiss
ions, and a spring. Despite testimony by ancient authors, many modern schol
ars have dismissed these traditional accounts as mistaken or fraudulent. Th
is paper presents the results of an interdisciplinary study that has succee
ded in locating young faults at the oracle site and has also identified the
prophetic vapor as an emission of light hydrocarbon gases generated in the
underlying strata of bituminous limestone.