Database for USGS Map I-1970 - Map showing the thickness and character of Quaternary sediments in the glaciated United States east of the Rocky Mountains

Abstract

U.S. Geological Survey (USGS) Miscellaneous Investigations Series Map I-1970 is a 1:1,000,000-scale map of Quaternary deposits (including both glacial and glacially related sediments, and any overlying Holocene sediments) compiled for the glaciated area of the United States east of the Rocky Mountains (that is, the area covered by the Laurentide ice sheets). Parts of southern Ontario, areas beneath the Great Lakes, and parts of the submerged eastern seaboard also are included on the map. The map has four principal geologic components that together provide the first regional three-dimensional view of these deposits. These components are: (1) the surface distribution of Quaternary sediments; (2) the total thickness of Quaternary sediments; (3) significant thin, surficial Quaternary units (“veneers” of sediment overlying the unit generally mapped for a given area); and (4) significant buried Quaternary sediments. The map is a regional synthesis and interpretation of available geologic data derived from about 850 sources of information. It was published in four sheets, as Map I-1970-A--D (Soller, 1993a, 1994, 1997, and 1998). It also was simplified and printed at the reduced scale of 1:3,500,000 (Soller, 1993b, 2001). Text and references to support the map are provided by Soller (1992). The Geographic Information System (GIS) data from which the map was printed were released on CDROM (Soller and Packard, 1998). To allow this large map to be printed, new digital methods were developed (Soller and others, 1990). The GIS and digital printing technology of the early 1990s required that the map be divided into manageable pieces. Therefore, the mosaic of 23 4-degree by 6-degree International Map of the World Series quadrangles, upon which the map was compiled, was taken apart, and each quadrangle was processed separately. Because the file size was quite large for a database of the entire map area, GIS files in the first version of this database (Soller and Packard, 1998) were provided by quadrangle rather than for the entire area. For each of these quadrangles, the geologic information was supported by a rudimentary vector base map adapted from existing paper and digital bases. With gradual advances in GIS technology, and owing to continued user requests for the map database, it became incumbent on us to reprocess the database in order to ensure its usefulness in a modern GIS. Data Series 656 contains the updated database, organized in ten feature classes in an ESRI Geodatabase. Reprocessing a published database for these and other reasons will, in time, become necessary for other agency publications. The experience gained in updating this map for use in a modern GIS may inform agencies as they develop plans to prioritize older publications in need of updating and may help agencies in estimating the resources necessary to address this important responsibility.