Geologic maps are the most important source of information when trying to learn about the geology of a place, and geologists have well-worn strategies and new techniques for visualizing the geology and deciphering key relationships from such maps. When examining a geologic map, a practiced geologist employs what visualization researchers call "disembedding", isolating and focusing on one aspect at a time – topography, map patterns, structural attitudes, etc. Geologists use disembedding to successively build mental models of the topography, the geology, and the relationship between the two. Other traditional techniques include the rule of V’s, down-plunge viewing, cross-cutting relations, mentally constructing cross sections of small areas, and mimicking geometry of structures with hand gestures.

To help students learn map-reading skills, we developed interactive 3D visualizations of (1) contours draped over digital topography, (2) rotating planes that intersect topography, (3) virtual geologic blocks that students can rotate and make partially transparent, and (4) geologic maps draped over digital topography. These interactive materials, available as web-based QuickTime VR movies and as VRML worlds on the GeoWall 3D stereo projection system, let students actively explore geologic maps, visualize structural geometries, and better learn the traditional techniques. Students also construct their own geologic maps and sections from satellite images draped over digital topography and from immersive 3D perspectives of geologically realistic virtual worlds. The various materials have shown great results with geology majors and with nonmajors and give students a jump on map-reading skills required for field studies. Interactive geologic maps are available at http://reynolds.asu.edu/