New Mexico Geological Society Annual Spring Meeting — Abstracts

This project involved the conversion of NMBM&MR Geologic Map 57: Geology of east half of Las Cruces and northeast EI Paso 1° x 2° sheets, New Mexico (Seager et al. 1987) into digital fonn using GIS technology. The project is sponsored by the NMSU Department of Biology, the WRRI and the NMBM&MR. The main points of the study were to produce a completely digital fonn of the published map, which includes the geologic map itself and the description of the geologic units found on the map. The map was created in the Arc/Info and subsequently placed into an Arc/Info and Arc/Niew format upon completion.

The initial step taken in this project was to scan a scribe sheet used to create GM-57. 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/lnfo, 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 coverage was essentially 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. 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 understand of the information contain on GM-57. The GIS database is in Arc/Info format and has FGDC metadata.