The linework was digitized in 1997 from a paper copy of the 1994 map at
the U.S. Geological Survey's Alaska Section (Geologic Division) facilities in
Anchorage, AK. The original Transverse Mercator projection of the map (Central
Meridian: 100*W; Scale factor: 0.926; Reference ellipsoid:(6371204m, 63712004m)) was
converted to an Albers equal-area coverage in ARC/INFO (version 7.1.2). The
resulting coverage did not align exactly with an Albers equal-area coverage of the
Alaskan coastline, so a rubber-sheeting operation was performed using points
along the coastline and major rivers to match an Albers equal area projection.
Map unit (polygon) locations and attributes were checked by the person responsible for
the digitizing, and spot-checked by one reviewer, by comparing a printed copy
of the coverage to the published map. Metadata were collected using document.aml
v. 7.1.1, distributed by ESRI, Inc.
None completed or planned.
Moll-Stalcup, E.J., Brew, D.A., & Vallier, T.L. 1994. Latest Cretaceous and Cenozoic
Magmatic Rocks of Alaska, Plate 5 in: Volume G-1, "The Geology of Alaska", Geology of
North America series (GNA-G1), Plate 5. Geological Society of America, Inc., Boulder, CO.
The completeness and quality of the geologic data in the digital
coverage is that of the published 1994 map, which summarized data collected prior to
that date (mainly since 1980). No recent data have been added. The geographic accuracy
of the published map has been slightly degraded by the rubber-sheet operation.