The Faults at Delphi, the Oracle, and the Tectonic Setting of the Gulf of Corinth: Case Example

Barbara Tewksbury, Hamilton College

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Students interpret data on the faults at Delphi, evaluate the tectonic context of the faults, and explore the proposed connection between faults and the Delphic Oracle of Ancient Greece.

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Structural geology course for geo majors.

Skills and concepts that students must have mastered

Faults, stereonets (planes, lines, poles to planes), focal mechanism solutions, general tectonic setting of the eastern Mediterranean and the Anatolian Plate.

How the activity is situated in the course

In some years, I have used this as part of a homework assignment and, in other years, as part of a take-home exam. I have also used it as a class/lab activity accompanied by more extensive reading on the Delphic Oracle (see Description below) and examination of the active Gulf of Corinth detachment.


Content/concepts goals for this activity

The primary goal is for students to apply content and concepts that they have already learned, but they also learn about faults and fluid flow, vein formation, practice with stereonets, and the usefulness of structural geology concepts in another discipline.

Higher order thinking skills goals for this activity

Interpret stereonets and combine with field data to analyze faults; interpret focal mechanism solutions; analyze faults in the context of regional plate motions.

Other skills goals for this activity

Description and Teaching Materials

Students read a brief context description for the faults at Delphi, plus deBoer et al.'s hypothesis (2001) that groundwater with dissolved ethylene percolated upward along intersecting faults at Delphi and that release of ethylene at the Oracle spring was responsible for inducing a trance-state in the Pythia (the woman at the Oracle who uttered the prophecies). Armed with this context, students use stereonets from deBoer's article plus descriptive information and photographs to interpret the nature of the faults and their slip. Students then evaluate whether the slip on the faults at Delphi is consistent with the focal mechanisms for earthquakes in the larger Gulf of Corinth region and analyze how regional plate motions in the eastern Mediterranean and Middle East are manifested in the focal mechanisms in the Gulf of Corinth and the types of faults at Delphi.

The Scientific American article listed in the references is a nice one for students to read as background for a follow-up discussion on faults, fluid flow, vein formation, and connections of structural geology to human/historical events. Adding consideration of the Gulf of Corinth as a modern, active low-angle detachment is something else that could be done.

If students do not have background on the tectonic setting of the eastern Mediterranean, the Gulf of Corinth, and the Anatolian Plate, this could be added in a previous class or as homework as background for the case example. References listed below provide a starting point for background on plate motions in the area.

Assignment for Delphi case example (Microsoft Word 2007 (.docx) 1.8MB May9 12)

Teaching Notes and Tips


Students individually submit written analyses with argument and evidence.

References and Resources

deBoer, J.Z., Hale, J.R., and Chanton, J., 2001, New evidence for the geological origins of the ancient Delphic Oracle (Greece): Geology, v. 29, no. 8, p. 707-710.

Hale, John R., de Boer, Jelle Zeilinga, Chanton, Jeffrey P., and Spiller, Henry A., 2003, Questioning the Delphic Oracle: Scientific American, August 2003, p. 66-73.

Piccardi, Luigi, 2000, Active faulting at Delphi, Greece; seismotectonic remarks and a hypothesis for the geologic environment of a myth: Geology, v. 28, no. 7, p. 651-654.

Moretti, Isabelle, Sakellariou, D. Lykousis, V., and Micarelli, L., 2003, The Gulf of Corinth: an active half graben? Journal of Geodynamics, v. 36, no. 1-2, p. 323-340.

McClyusky, S., Balassanian, S., Barka, A., Demir, C., Ergintav, S., Georgiev, I., Gurkan, O., Hamburger, M., Hurst, K., Kahle, H., Kastens, K., Kekelidze, G., King, R., Kotzev, V., Lenk, O., Mahmoud, S., Mishin, A., Nadariya, M., Ouzounis, A., Paradissis, D., Peter, Y., Prilepin, M., Reilinger, R., Sanli, I., Seeger, H., Tealeb, A., Tokxoz, M.N., and Veis, G., 2000, Global Positioning System constraints on plate kinematics and dynamics in the eastern Mediterranean and Caucasus: JGR, v. 105, no. B3, p. 5695-5719.