ORBIT TO OUTCROP AND OUTCROP TO ORBIT: USING THE WORLD’S GREAT SITES FOR TEACHING STRUCTURAL GEOLOGY AND GEOLOGIC MAPPING

High resolution satellite imagery in Google Earth offers the opportunity for students to “visit” spectacular fold and fault terrains that are otherwise inaccessible and to learn how to map and interpret geologic structures in ways that add to, and improve on, outcrop-level mapping. Fold and fault terrains in layered rocks that are exposed in semi-arid to arid regions of the world are outstanding for practice in pattern recognition and interpretation, as well as experience in the range of structures in deformed layered rocks. For many years, I have used the 3D fly-through capability of Google Earth to help students visualize structures in three dimensions and to teach them how to do geologic mapping and draw geologic cross sections. The very high resolution of Google Earth imagery, plus the tilt-and-fly-through capability, gives students a virtual experience at nearly the outcrop level. My students’ first mapping experiences are done in Google Earth, where they learn to define mappable units, map outcrop traces of contacts, and determine the geometries of structures. For accessible areas where students will subsequently work in the field, students use Google Earth to do preliminary mapping and interpretation, discover structures and relationships that are not easily visible from the ground, and plan targeted field work to check interpretations and to answer questions that are not resolvable in the imagery. In the past, we have mapped both digitally in Google Earth and by hand on mylar overlays on high resolution printouts from Google Earth Pro. The recent launch of Arc2Earth, where Google Earth imagery is available directly in ArcMap, will allow more sophisticated digital mapping prior to field work.

I have also recently used the same approach for teaching recognition and interpretation of structures to the newest group of NASA astronauts. They began by using Google Earth to learn how to interpret the spectacularly exposed fold and fault structures that they will see first hand while on orbit on the ISS. Then, before going into the field in northern New Mexico, they used Google Earth and other orbital data sets to map structures in several areas. Visiting those areas in the field to check interpretations, collect field data, and augment their maps underscored the need for ground truth and the critical role of “outcrop to orbit”.