Digital geologic maps that use a virtual globe interface, like Google Earth (GE), are a relatively new medium for presenting geologic data and interpretations. This format incorporates significant advantages over traditional paper geologic maps and cross sections, including:

• A user-friendly and intuitive interface for novice users, which enhances the utility of geologic information for students and the general public;

• The ability to view multiple maps simultaneously and seamlessly transition between maps by zooming or panning;

• The option of displaying cross sections in situ on geologic maps as vertical interpretations of above ground or subsurface geology; and

• A facility for integrating map interpretations with individual outcrop and field data, which traditionally has been relegated to field books.

This paper outlines a digital maps package, composed of geologic maps of regions of Virginia, as a proof of concept and template for possible future expansion beyond state boundaries or into the realm of soils, geomorphological, or hydrological maps. Through collaboration amoung universities, state agencies, and federal organizations we have assembled a multi-layered, fully interactive map accessible through two portals: the stand-alone Google Earth application, and as a web page using the GE web browser plug-in (GE API). All maps within this package have selectable polygons, polylines (“paths”), and points (“placemarks”), many of which contain associated metadata, such as lithologic descriptions, fault information, outcrop orientation data, etc. At the smallest scale, a generalized geologic map of Virginia is displayed with a selectable overlay of regional physiographic provinces. As users pan and zoom, the maps automatically transition from generalized statewide maps to more refined regional maps and 1:24,000 scale quadrangle maps. Many of the map components (cross sections, explanations, and orientation symbols) cannot be created directly in GE but are added to the digital maps using KML scripts derived from an HTML-based toolkit.

Challenges related to the method of digital map development described herein include: effective importation of vector data from other GIS databases, style limitations inherent in GE, and time-consuming labor associated with the digitization of polygons and polylines in GE. There are also conceptual challenges at the user interface level, including possible misconceptions with the display of vertical cross sections due to the inability to look below the GE digital elevation model and associated surface imagery.