BUILDING INTERACTIVE GEOLOGIC MAPS IN GOOGLE EARTH

Geologic field data collection, analysis, and map compilation have undergone a major change in methodologies, largely precipitated by GPS- and GIS-equipped mobile computers paired with internet-based virtual globe visualizations. Ruggedized mobile PCs can record a wide spectrum of geologic data and facilitate iterative geologic map construction and evaluation on location in the field. Spatial data and interpretations can be presented in a variety of formats on virtual globes, such as Google Earth, NASA World Wind, Microsoft Virtual Earth, and ESRI ArcGIS Explorer. We present examples of Google Earth-based geologic maps at a range of scales, from highly detailed 7.5 minute quadrangle-sized field areas up to more generalized state-sized maps. Interactive features of these maps include: 1. The ability to zoom, pan, and tilt the globe and map overlays to any desired viewpoint; 2. Selectable, draped polygons of geologic units that can be rendered semi- or fully-transparent, allowing the viewer to examine the underlying terrain; 3. Structural symbols (e.g., strike and dip) positioned at outcrop locations, which can also display associated metadata; 4. Cross-sections that emerge from the subsurface in response to a slider control; and 5. Other data, such as digital photos or sketches, as clickable, zoomable objects in their correct field locations.

We have designed exercises for introductory and advanced earth science courses that use interactive, Google Earth-based geologic maps to explore concepts such as the relationships between topography and geology, geologic time and the spatial juxtaposition of units, coupled interpretation of surface geology and cross-sections, and tectonic assembly of ancient orogens. Preliminary evaluation suggests that these interactive maps communicate geologic data and interpretations in a format that is more intuitive and easy to grasp than the centuries-old format of paper maps and cross sections. Future work will include interactive surficial geology maps that will document glacial and coastal features and highlight associated geomorphic change as recorded by historical images and records.