GEOLOGIC MAPPING WITH GOOGLE EARTH: A GIS ALTERNATIVE

Google Earth is widely used for map applications due to its extensive database of satellite imagery, roads, and other geographic features. Although the vast majority of users rely on the software for simple routing and recent satellite data, it has powerful functionality as a tool for creating custom geologic maps as KML files. Coupled with Earth Point, a free online Excel to KML converter, large geologic datasets can be quickly added to Google Earth as point files and represented by a variety of clickable icons complete with station data (e.g., station name, lithology, stratigraphy, structural, geochemical). Using custom icons created from any image file, Earth Point’s Excel conversion tools allow for bulk insertion of structural symbols rotated according to strike/bearing and noted with dip/plunge data. Although lacking the powerful querying abilities of more widely used GIS software (e.g. ESRI and Autodesk products), Google Earth coupled with Earth Point is far easier to learn, can be used free of charge, and doesn’t require significant computing power. Google Earth can be used to create boundaries and polygons based on the distribution of incorporated point data, and can be used to link map features and web data. Image overlay tools make georeferencing raster maps (e.g., topographic, geologic) a simple task and facilitate creation of KML-based geologic maps using historical and new geologic datasets. Additionally, use of a laptop/tablet computer with Google Earth software, a GPS device, and internet connection (e.g., a tethered smart phone or wireless hot spot) allows the software to be used in the field as a real-time mapping tool. The ability to quickly locate stations, utilize satellite imagery and recent road data, and add-manipulate geologic data onto a digital map in real-time has significant advantages over traditional pen and paper mapping, especially in typical “roadside” geologic mapping activities. Although some aspects of Google Earth limit its ability to create finished geologic maps (e.g., inability to create fault ornamentation), the advantages of Google Earth make it a functional alternative to expensive and difficult to learn GIS software when the full capabilities of such software is not essential to a project.