Digital Geologic Map of the Altiplano and Cordillera Occidental, Bolivia

The geologic map of the Altiplano/Cordillera Occidental was produced digitally from fifteen, 1:250,000 scale, field compilation maps. These paper maps were made by Servicio Geológico de Bolivia (GEOBOL) geologists over the last decade. After examination of the field maps it was determined that the best method for capturing the geologic data digitally was by means of an optic scanner. Because of the condition of the maps and the fact that they had been hand colored the geology was transferred to mylar stable-base overlays at 1:250,000 scale using a fine (.35 mm) ink pen prior to scanning. The overlays were then scanned into ARC/INFO using a Tectronics 4991 digital drum scanner. The 15 scanned images were converted into ARC/INFO coverages and edited in ARCEDIT using all 137 geologic units derived from the original field compilation maps. The resulting 15 digital maps at 1:250,000 scale were plotted in color on an electrostatic plotter and then reviewed and edited by USGS and GEOBOL geologists using new geologic information from field studies conducted during the spring and fall of 1990.

Data files opened and inspected; projection was implicit (parameters shown in this record were given in an aml script and appear to be appropriate) and unit symbol numbers were not associated with the map symbols or unit descriptions. These associations were adduced by inspection of the printed map and the data; spatial reference and attribute information were added to this record.