THE NEW ALASKA GEOLOGIC MAP

A new bedrock geologic map of Alaska has recently been prepared and is presented; it will ultimately be published as a USGS Scientific Investigations Map by F.H. Wilson, C.P. Hults, C.G. Mull, and S.M. Karl. This map integrates original published and unpublished sources as well as new mapping and reflects more than a century of work in Alaska by a host of geologists and nearly two decades of compilation work. A number of regional geologic maps were released as the compilation process was ongoing. Each of these regional compilations is an integral part of the new state map. Alaska remains mapped only at a reconnaissance level in many areas, and conflicting interpretations and map boundary mismatches are common. Using the regional compilations and source maps from areas where regional compilations were not available, we tried to integrate the geology. However, in some cases, available data did not permit resolution of map boundary mismatches. We utilized the best original geologic map information and any new data available in the compilation.

The compilation is in two parts. One part consists of spatial datasets and attribute databases containing extensive data regarding sources, map unit descriptions, lithology, geologic setting, and age and tables of radiometric age determinations. For every polygon and line, the source map data is preserved in a database. The second part, a draft of which is presented, is a printed, somewhat generalized, map. The digital version of the map contains about 450 distinct map units, whereas the printed version contains approximately 220 generalized map units.

Compilation on this scale could only be done with the assistance of many geologists. USGS Emeritus scientists and volunteers were important contributors to this effort, providing many insights, much unpublished data, and much appreciated advice. They included Robert Detterman, William Patton Jr. , Donald Richter, Bill Brosgé), Robert Chapman, and Donald Grybeck (all deceased), as well as retired geologists Florence Weber, Warren Coonrad, Hank Schmoll, Lynn Yehle, David Brew, Thomas Hamilton, Jeanine Schmidt, Cynthia Dusel-Bacon, Alison Till, and Dwight Bradley. Active USGS staff who contributed to this effort by providing data and participating in discussions included Julie Dumoulin, Rick Saltus, Marti Miller, and Peter Haeussler.