U.S. Geological Survey
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Reston, VA 20192
Telephone: (703) 648-6907
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In the 1980's, the geology shown on USGS Map I-1970-A, -B, -C, and -D was compiled according to traditional methods, using ink on mylar. The draft map showed the thickness and character of Quaternary sediments in the United States east of the Rocky Mountains, at a scale of 1:1,000,000. The map area at this scale is more than 30 square feet. The geologic information was contained on four separate mylar overlays. The map contained a highly complex portrayal of the geology, and it was determined that conventional methods of map production would yield a substandard product because of difficulties in registering color separations with peelcoats. In 1987, after discussion between author and cartographer, it was decided that the emerging technology of computer-based mapping might offer the precision needed to produce high-quality printing negatives. Also, in discussions with potential users of the map information, it became clear that if the map were in GIS format, its utility would be significantly enhanced.
Methods for producing this type of map did not, however, exist in 1987. Therefore, we sought and obtained funding through the USGS Director's "sweepstakes", which awarded "seed money" to selected projects that proposed to develop innovative methods in GIS and digital cartography. In 1988-89, we developed a method for scanning the manuscript maps, manipulating the digital map data, and outputting the data as color separates for map printing. This method required a Tektronix 4991 autovectorizing scanner, Arc/Info, and a Scitex Response-80 editing workstation and film writer. Details of the method were published as a user's manual (Soller and others, 1990). Although the hardware specifications described in the publication are no longer useful because of technological advances, the general approach and processing steps (e.g., methods for map registration) still are applicable.
In the early 1990s, the manuscript maps were scanned and edited in Arc/Info by the authors and by others. Data files then were submitted to the National Mapping Division for processing on the Scitex and for the generation of negatives to make proofs. These negatives were registered to negatives of the conventional greenline base map. Text and figures were produced as graphic files and placed manually; when assembled, the package was submitted for printing. The first of these maps, I-1970-A, was published in 1993 (Soller, 1993). The last map, I-1970-B, was published in 1998. The edited digital data also were used to build a geographic information system (GIS) database for analysis. The digital data were published as USGS DDS-38 (Soller and Packard, 1998), which is online at http://pubs.usgs.gov/dds/dds38/.
Soller, D.R., and Packard, P.H., 1998, Digital representation of a map showing the thickness and character of Quaternary sediments in the glaciated United States east of the Rocky Mountains: U.S. Geological Survey Digital Data Series DDS-38, one CD-ROM. http://pubs.usgs.gov/dds/dds38/.
Soller, D.R., Stettner, W.R., Lanfear, K.J., and Aitken, D.S., 1990, A user's manual for a method of map scanning and digital editing for thematic map production and data-base construction: U.S. Geological Survey Circular 1054, 38 p.
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