Through the centuries that followed, there was a persistent but unproven theory that the mysterious vapors of the inner chamber were the result of some kind of natural subterranean activity beneath the temple, like a hot spring or a volcanic process of some kind.
In fact, by the beginning of the 20th century, conventional archeologists had pretty much completely investigated the site at Delphi, searching for evidence that would support the vapor theory.
But the traditional methods of archeology failed to produce any such evidence. For the next 80 years or so, the archeology community more or less dismissed these fantastic spiritual stories of the oracle as just exaggerated myths, to be archived along with the other ancient Greek myths of gods and spirits.
In this video, presenter Frederick Tamagi reveals what archeologists eventually discovered about Delphi.