Introducing Geologic Map Interpretation and Cross Section Construction Using Google Earth In a Structural Geology Course

A typical approach to maps and cross sections in a structural geology course begins with concepts (strike and dip, types of contacts), map patterns of contacts with and without topography, and construction of cross sections. Despite hands-on practice, clay models, and 3D block diagrams, many students struggle with map interpretation, the concept of strike and dip, structures in 3D, and cross section construction. Using Google Earth, coupled with a revised approach to the basic topics, appears to make a difference for most students.

Instead of starting with concepts and map interpretation, my students start by making their own geologic maps. They visit an area in Google Earth that has folds, topography, and distinctive units, and they make a geologic sketch map of the area. Being able to tilt and view from any direction allows the students to make maps successfully, despite having little or no experience. They can also see directly which way contacts are inclined and add inclination directions to their maps. The tilt and fly-through views also help students successfully sketch topographic profiles and cross sections. We then address the concept of strike using an area near Khvorgu, Iran (27 34N, 56 26E), where the elevations are adequate in Google Earth to construct strike lines and calculate dip. After creating several more maps and cross sections of areas viewed in Google Earth, we generalize the concept of outcrop patterns and begin to work with “flat” geologic maps. For the first time in 30 years of teaching structural geology, I didn't have any students who struggled with maps and cross sections.

Areas of interesting structures and adequate image resolution that lend themselves well to this approach include portions of the Zagros, Anti-Atlas Mountains, Dasht-e Lut (Iran), west-central Pakistan, east-central Afghanistan, Makran Coast, southern Tian Shan, and south-central Algeria.