PROTOTYPE GIS DATABASE FOR THE DNAG GEOLOGIC MAP OF NORTH AMERICA

In 1998, the Geological Society of America (GSA) and the U.S. Geological Survey (USGS) National Geologic Map Database project (NGMDB) agreed to cost-share the digital preparation of the Geologic Map of North America (GMNA). The preparation required digitization of the hand-drawn, author-prepared, geologic maps in order to provide digital data for two purposes: (1) to allow the GSA to print the GMNA, and (2) to permit the NGMDB project to develop a prototype database. In 2005, the GMNA was printed (Reed, J.C. Jr., Wheeler, J.O., and Tucholke, J.E., compilers, 2004, Geologic Map of North America: Decade of North American Geology Continental Scale Map 001, Boulder, Geological Society of America, scale 1:5,000,000). In 2006, the NGMDB project began to design and create the prototype. The first version of the GMNA prototype database contains the descriptive information for geologic units shown on the map, and serves as the fundamental entity from which products of the map then can be derived.

The GMNA prototype includes both continental and seafloor geologic units in the western United States and Canada. This area was chosen due to its relatively complex geology and abundance of both onshore and offshore map symbology displayed in the published GMNA. The main objective of the prototype was to determine the most efficient way to convert the print files (Adobe Illustrator format, with more than 1500 layers on each of two sheets) into a topologically clean ArcGIS geodatabase.

The creation of this database and its enhancement to include new mapping and more richly attributed information is a daunting task that will take a significant amount of time and effort. Recognizing that a group of dedicated and knowledgeable scientists is essential to make this database useful and to keep its content up to date, GSA may develop a consortium of geological agencies to manage the database. With development of the prototype database, the USGS National Geologic Map Database project provides a basis for this consortium to proceed.