MELDING TRADITIONAL AND MODERN TECHNIQUES TO CREATE AND DISTRIBUTE DIGITAL GEOLOGIC MAPS IN MONTANA

The Montana Bureau of Mines and Geology (MBMG) has served as Montana’s geologic survey since 1919 and has a deeply rooted tradition in classical field mapping. This tradition continues today but has been greatly enhanced by emerging remote sensing and GIS technologies. MBMG uses these technologies, combined with web-based services, to routinely create and distribute digital geologic maps.

MBMG field mapping is exclusively done on paper USGS topographic bases; however, ruggedized tablets designed for digital mapping are being tested and could potentially replace paper maps. GPS devices equipped with GIS software are routinely used in the field to visualize georeferenced data such as USGS topographic bases, existing geologic maps, satellite imagery, and digital elevation models; all of which greatly aid traditional field mapping. A GIS quick form is also loaded onto the GPS devices to record station locations, general geologic notes, structure data, and other miscellaneous geologic data. This form is easily saved on a desktop or laptop computer that allows the geologist to quickly visualize, query, and export field data to other software packages (spreadsheets, structural analysis software, etc.).

Finalized geologic field maps are traced onto mylar overlays that are subsequently georegistered and digitized using GIS software; MBMG stores geologic map data in multi-user geodatabases that adhere to the cartographic representations set forth by the Federal Geographic Data Committee. The digitized maps are then exported to graphic design software for cartographic finishing. Portable document format (PDF) copies of the final geologic maps, accompanying GIS data, and technical reports are made available to the public through MBMG’s website featuring a searchable digital catalogue and interactive map. MBMG digital geologic maps can also be downloaded from the National Geologic Map Database website.