Introduction

Geologic maps, in our view, are the most important type of geologic information. Geologic maps provide the basis for exploring for energy and mineral resources, evaluating geologic hazards, and making decisions about land use. Teaching students to understand geologic maps is a fundamental goal of an undergraduate geology curriculum.

We have found that movies and images of geologic maps draped over digital topography provide an excellent way for students to learn how to read geologic maps and visualize the geology depicted on such maps. Interactive 3D Geologic Maps contains QuickTime Virtual Reality (QTVR) movies where traditional geologic maps are transformed into interactive three-dimensional geologic maps. We have generated two types of these movies. In QTVR object movies, students can spin the map-draped geologic terrain 360 degrees around a vertical axis to view the geology and the topography from any direction. In QTVR panorama movies, students can tour an entire 3D geologic map by clicking and dragging on the movie to scroll or zoom in and out on any location. A QTVR panorama of the scanned geologic map, along with a legend, accompanies each map area.

In Quick Time Virtual Reality movies, the student spins or otherwise moves across the map by clicking and dragging the cursor inside the movie. For panorama movies, students can click the + or – buttons in the control bar to zoom in or out of a particular area of interest on the map. Once students have zoomed in on the map, they may click and drag in the movie to pan around to different parts of the map. In object movies, students click and drag left or right to spin the terrain, and can zoom in and out using the control bar.
A significant feature of Interactive 3D Geologic Maps is that students can easily observe how the geology and the topography relate. Another unique aspect of Interactive 3D Geologic Maps is that students can zoom in or out on an area, enabling them to focus on the geology at a specific location.

These interactive 3D maps were created by scanning published geologic maps and draping them over digital topography using Corel’s Bryce4. Most of the geologic maps are from the U.S. Geological Survey (USGS); the digital topography files (Digital Elevation Models - DEMs) are from the USGS and were manipulated (mostly converted to grayscale, elevation maps) using MicroDEM written by Dr. Peter Guth. Bryce4 was configured to automatically generate 36, 72, 108, or 144 three-dimensional perspectives (bitmap images) for each map, each image being 800K to 3 Mb in size. These images were combined into a QuickTime Virtual Reality (QTVR) object movie using the program VR Worx. The standard QTVR object movies were derived from 800 X 600 pixel images, and mostly are between 1 and 3 Mb in size. Larger movies have been created from 1600 X 1200 pixel or 1200 X 900 pixel images; these are spectacular, and are available at http://reynolds.asu.edu/geomap3d/geomap3d_home.htm.

Use of the Materials

In this contribution, the different types of movies are accessed via the links listed below. The movies are organized alphabetically by location as follows:

Bald Mountain, Wyoming Laramide (Late Cretaceous to Early Tertiary) uplift in the Big Horn Mountains flanked by Mesozoic sedimentary rocks: legend; flat map; panorama map movie; spin movie

Calabasas, California Deformed Tertiary and Cretaceous sedimentary and volcanic units, with numerous erosion features: legend; flat map; panorama map movie; spin movie

Hollidaysburg Folio, Pennsylvania (30-minute quad) Amazing folds of lower Paleozoic formations in the Martinsburg area of the Ridge and Valley Province: legend; flat map; panorama map movie; spin movie

Mescal Mountains, Arizona Strike ridges and dip slopes of Paleozoic and Precambrian strata; Tertiary normal faults; Late Cretaceous pluton: legend; flat map; panorama map movie; spin movie

Mingus Mountain, near Jerome, Arizona (15-minute quad). Basalt mesa; several unconformities; Precambrian structures: legend; flat map; panorama map movie; spin movie

Sunland, California Tilted and locally folded late Cenozoic units and older metamorphic and granitic rocks near Los Angeles: legend; flat map; panorama map movie; spin movie

Acknowledgements
Development of these materials was supported in part by the NSF-funded Hidden Earth Project (EAR 9907733 to Stephen Reynolds, Michael Piburn, and Barbara Tewksbury), NSF-funded Hidden Earth Curriculum Project (DUE 0127595), and the U.S. Department of Education Arizona Teacher Excellence Coalition (AZTEC) project (P336B990064 to James Middleton and others).

References
Anderson, D.S. and Creasey, S.C., 1967, Geologic map of the Mingus Mountain quadrangle, Yavapai County, Arizona: U.S. Geological Survey, Geologic Quadrangle Map GQ-715, scale1:62500.

Butts, Charles, 1945, Hollidaysburg-Huntingdon folio, Pennsylvania: U.S. Geological Survey, Geologic Atlas of the United States Folio GF-227, scale 1:62500.

Darton, N.H. and Salisbury, R.D., 1906, Bald Mountain-Dayton folio, Wyoming: U.S. Geological Survey, Geologic Atlas of the United States Folio GF-141, scale 1:125000.

Dibblee, T.W., Jr., 2001, Geologic maps of the Santa Monica Mountains, California: Santa Barbara, Dibblee Foundation CD-1 (Calabasas and Sunland quadrangles).