CREATION OF A DIGITAL GEOLOGIC MAP USING FREE AND OPEN SOURCE SOFTWARE AND INEXPENSIVE RECREATION-GRADE GPS UNITS: AN EXAMPLE FROM NORTHERN NORWAY

Free and open source software and inexpensive recreation-grade GPS units were used exclusively to aid ongoing fieldwork on the arctic Kjerringøy peninsula, north of Bodø, in Nordland, Norway. Lithologies within the study area consist of medium- to high-grade schists, marbles, and gneisses that are intruded by nonfoliated tonalitic granitoids. The area has recently been interpreted as a portion of Laurentian basement orphaned on the western margin of Baltica during the Early Tertiary opening of the northern North Atlantic. To assist in creating detailed structural and lithologic maps of the area, averaged coordinates were obtained using Garmin GPS60 and Garmin eTrex handheld GPS units for all locations where data was collected. Using gpsbabel (version 1.40), location information was transferred to a laptop computer and stored as a non-proprietary CSV text file. All location data was imported into a PostgreSQL object-relational database system (version 8.4.5) with additional GIS capabilities provided by the PostGIS (version 1.4.2) extension. In addition to providing increased storage redundancy, use of a PostGIS-enabled database allowed data to be more easily manipulated and supplemented using Quantum GIS (version 1.4.2) as a front-end. The use of Quantum GIS allowed data collected using traditional, non-digital techniques to be transcribed into the PostGIS database to which it was linked. Structural measurements, lithologic descriptions, contact information recorded on working maps in the field, and photographs, collected by different workers at different locations, were all added to the PostGIS database at the end of each field day. This rapidly-developed geological database was then easily exported as a non-proprietary SVG text file or proprietary ESRI Shapefile as needed. We present a working geologic map of the study area, created entirely using the described software and techniques, as well as our current thoughts on the history of the area.