New Mexico Geological Society Annual Spring Meeting — Abstracts

This project involved the conversion of NMBM&MR Geologic Map 60: Geology of southwest quarter of Las Cruces and northwest El Paso 1° x 2° sheets, New Mexico (Seager 1995) into digital form using GIS technology. The project is sponsored by the WRRI, Department of Geological Sciences at NMSU, and the NMBM&MR. The purpose of this project was to produce a completely digital form of the GM-60 so that the GIS coverage could be used in an aquifer assessment study.

The initial step taken in this project was to scan a scribe sheet used to create GM-60. Scribe sheets are used the cartographic process for NMBM&MR map production. The original image was a TIFF file that was then converted, using Arc/Info into a grid file (Arc/Info raster file format) that was georeferenced to UTM, Zone 13 NAD 27. This grid was scanned from a scribe sheet supplied by Glen Jones of NMBM&MR. Next, the linework was traced on the computer using the grid as a backdrop to create a coverage. This method was used instead of digitizing a hard copy of the original map because it was felt that copying the grid and producing a GIS coverage would be more precise and geologically accurate. The tracing of the grid was done within the Arc/Info program using Arctools commands.

This process was completed after going through and fixing all of the necessary edits. Errors were identified by comparing the output of the digital map with the original scribe sheet. The map and description can then be printed out in different forms, whatever may be required for use or display. This work created a digital map that is accurate and hopefully more useful than the hard copy of the map. This process has been by no means perfected but is a useful format when converting a hard copy of a map to digital form. Therefore, use of this GIS database should be done in conjunction with the original hard copy map to ensure a complete of the information on GM-60. The GIS database is in Arc/Info format and has FGDC metadata.