TEACHING STRATIGRAPHY IN THE FIELD: THE ARCHAEOLOGICAL SITES REGION OF CENTRAL OAXACA, SOUTHEASTERN MEXICO

Given that actual fieldwork done in connection with geosciences curricula has declined in the last years for several reasons, such as mounting costs, and that national protected areas of various kinds, besides natural features or man-made monuments worth preserving, also include interesting natural settings, whose knowledge would add to their touristic/visiting value, it is quite appropriate to conduct curricular fieldwork there.

In Mexico, Central Oaxaca is an ideal region to do this, because: (a) There lie world famous Zapotecan archaeological sites [e.g. Monte Albán, Mitla, Yagul, Dainzú], and Colonial historic monuments [e.g. Oaxaca City Center, and numerous ex-haciendas dating back to Colonial times]. (b) Geologically this region includes rock bodies ranging in age from Late Proterozoic to Late Cenozoic, which record a wide genetic spectrum rarely seen anywhere else [e.g. plutonic, hypabyssal, volcanic lavic and pyroclastic, metamorphic, sedimentary marine, and continental], and a complex geologic history that includes Pre-Cambrian continental collision events, Mesozoic continental and marine sedimentary events, Cenozoic tectonic (compressive and extensional), magmatic, and continental sedimentary events.

Hence, Central Oaxaca is perfect to teach Stratigraphy, because one can apply its principles and illustrate nearly all its concepts in many places just a few kilometers apart: One could examine the different kinds of rock bodies, and nearly effortlessly do the leap to the stratigraphic unit concept, and to perceive the need of having several classes of them, so to best characterize them; further one can analyze their space/time relationships, and workout such relations for the lithogenetic events they record. The same could be done with the depositional systems making up the formations, and detect from them the environment where they originated. Finally, integrating the information on the Cenozoic Valle de Oaxaca units, one could outline the tectono-sedimentary evolution of the Valle de Oaxaca Graben, so accomplishing Stratigraphy’s major goal: making cognitive blocks to reconstruct Earth’s History. A multimedia precourse show would enhance this teaching. Learning Stratigraphy this way, and knowing this geologic information would greatly benefit both students and visitors alike.