Greek historians wrote of an oracle at Delphi who provided cryptic consultation
to pilgrims plagued with questions. For about 12 centuries Delphic women chosen
for this job delivered the advice of the gods, from family matters to choosing
sides during times of war. During the late Bronze Age, around 1200 B.C., they
translated for the Earth goddess, Gaia, and later in the eighth century B.C.
spoke as Apollos vocal instrument when this god took over the sanctuary.
The oracle sat on a three-legged stool in the interior recesses of the temple, calmly delivering her prose while inhaling the breath of the gods. This breath, or pneuma, emanated from fissures in a floor left naked to the earth, according to classical accounts. Springs bubbling to the surface, they said carried sweet-smelling fumes. Some days and months were better for prophecy than others. The oracle spoke specifically on the seventh day after each new moon, but not at all in winter. If the temples visitor demanded a forced performance at the wrong time, the oracle might run wild and frantic around the room delivering her prophecy in a frenzy.
Throughout this time, the sacred site remained in a unique geological location. According to a team of four researchers led by geologist Jelle de Boer of Wesleyan University in Middletown, Conn., the temple was built over the intersection of two faults: one young and active and the other old and probably inactive. Since 1996, de Boer and colleagues in the fields of archaeology, chemistry and toxicology have been exploring the implications of these faults. Embedded in oily limestone, the faults vented hydrocarbon vapors through fissures in the bedrock and continue to bubble forth ethylene, ethane and methane in neighboring springs today.
All three hydrocarbon gases have the potential to produce an altered mental state, says Henry Spiller of Poison Center at Kosair Childrens Hospital in Louisville, Ky., who published a paper on the toxic aspects of these gases in the April issue of Clinical Toxicology. Ethylene in particular would have the strongest effect and is often described as a sweet-smelling gas. The onset of the effects from ethylene are nearly immediate. The dose needed for an awake euphoric feeling are significantly less than that needed for deep operable anesthesia, Spiller says. During the first human experiments with ethylene as an anesthetic gas in 1923, most subjects had a very pleasant experience. However two people in the 12 studied had periods of excitement, confusion and combative behavior, similar to a frantic oracle on a bad day.
The philosophers in the first century wrote of gases producing euphoria and of a spring emanating from fissures, or chasms, in the bedrock inside the oracular chamber. But a dichotomy arose in the 20th century between ancient and modern interpretations for the geological source of the oracles inspiration. In 1892 and following years, French archaeologists including Pierre Amandry excavated the temple ruins and were disappointed to find fissures and water, but not the opening of a chasm. In 1904 a visiting English scholar A. P. Oppé deemed the ancients were perpetuating a myth or worse a blatant lie. He stated that Delphi did not sit on volcanic land and therefore the bedrock never emitted gases. Amandry in 1950 published a book also declaring the area volcano- and vapor-free. Over the decades the original French finding of water and fissures was forgotten and the Greek interpretations ignored. In their place came a standing assumption that the ancients were wrong.
Geological features beyond the immediate temple site provided more modern explanations on how the myth got started. The sanctuary of Apollo sits at the base of Mount Parnassus, where faults crisscross the region like wrinkles in the palm of an aged hand. Motion along the Delphi fault, which strikes east-west under the sanctuary, is thought to have caused the destruction of Apollos older temple in 373 B.C. But ruins and landslide deposits obscure the exact site where the fault runs below the temple. Questions arose concerning the role of this fault in the rise of the mysterious vapors.
Wesleyan University graduate student Emily Hager stands beside the exposed face of the Kerna fault. Photo courtesy of John Hale.
Archaeologist John Hale of the University of Louisville in Kentucky took some cajoling from de Boer to begin what would become a five-year expedition to determine the veracity of the ancient accounts. Over a bottle of Dão, a Portuguese red wine, the two made a bet. Jelle de Boer caught my interest with his description of exposed fault planes that he had seen on the slope of Mount Parnassus east and west of the oracle site, and with his assumption that this fault represented the chasm in the earth that ancient authors linked to the Delphic oracle, Hale says. It took a bet or a challenge to start this project because for almost a century it has been an article of faith among archaeologists, historians and classicists that the ancient traditions about the Delphic oracle were all wrong. I was very reluctant to admit that a geologist might be able to prove that it was modern scholarship that was wrong, and the ancient authors were right.
Last year in the August issue of Geology, de Boer and his team reported the discovery of a second fault they called Kerna, after a spring northwest of Apollos temple, and the gaseous findings of the spring. The Kerna and Delphi fault zones contain numerous extensional fissures, de Boer says. Where the faults intersect the bedrock is especially permeable. With regard to the absence of volcanic fumes, de Boer says: Fractures all over the world emit gases. Here in New England, for instance, radon surfaces along faults in many areas. Along the fractures in Delphi, warm groundwater significantly enriched in calcium has emerged for ages. The springs left deposits of travertine below the temple and among the ruins. Geochemist Jeffrey Chanton of Florida State University found methane and ethane still trapped in the travertine. The ethylene, a less stable molecule, he found still emerging from Kerna spring, but not in a spring 100 meters to the east of the temple. This finding suggests that the sites of hydrocarbon emissions at Delphi vary in output and are rather localized, the authors say.
Delphi is not the only Greek site where hydrocarbon gases emerge. On the island of Zakynthos to the west, where gas springs and tar pits are tourist attractions, Chanton found spring water with ethylene levels similar to those in Delphi.
Now de Boer and his team have opened the flood gates for further research to investigate the truth of the ancient accounts. It is interesting to note that the Delphi oracle never held sessions during the winter months, when the god Apollo was believed to have gone north to the land of the Hyperboreans. de Boer says. This suggests that the gas emissions at Delphi may have diminished during the colder periods.
Geologist George Davis of the University of Arizona runs a seminar that integrates geology and archaeaology. In January, Hale was one of his guest lecturers. Im confident if someone would go with Hale to that site, they would be convinced that at least one fault passes right through the site and that gases have been measured coming out of the fault zone that would have affected people, including the oracle, in the enclosed chamber above the fault, Davis says. More interpretive challenges of what may have happened still exist, but overall their story holds together.