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This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. INTRODUCTION Topographic surveys of abandoned, acid producing mine dumps were performed at four sites in Colorado to provide reference maps for U.S. Geological Survey research projects for geochemical and geophysical characterization of mine dumps. Two of the sites are located in southwestern Colorado near the town of Silverton, and the other two sites are located in central Colorado near the town of Leadville. The sites have been named for the mines located on them. The sites near Silverton are located along Cement Creek just north of town, and have been named the May Day (also known as BLM60) and Yukon (also known as Gold Hub) sites (Figure 1). Those near Leadville are located east of town on Ball Mountain and are named the Venir Pile and Sunday #2 (Figure 2). The topographic base maps resulting from these surveys contain information useful to ongoing research. Included in the maps are topographical features such as roads and hills, geophysical profile locations and grids, some geochemical sampling cells, biochemical sampling points, and other pertinent features such as vegetation "dead zones" produced by acid runoff from the dumps. The goal in producing these maps was to tie sample sites to topography, in some cases helping to interpret data. Many of the sites may need to be reoccupied in the future, accordingly steel pins (12" nails) were placed in the ground at all EDM locations to facilitate surveying of additional points or measuring changes of features such as vegetation boundaries with time. EQUIPMENT A Sokkisha Set 2 electronic distance meter (EDM) was used for surveying. A a HP-7 IB handheld computer was used for data logging. Digital surveying data were transferred directly from the EDM to the HP-7 IB. A corner reflector, tripod, barometer, thermometer and notebook completed the field equipment. The computer program used to record and download of data from the EDM to the HP-716 is described in Lucius (1997). Distances are estimated to be accurate to 1-2 cm, and elevation differences accurate to 2-4 cm. While this instrumentation is capable of much more precise surveying, this was not warranted for our purposes. Absolute positioning of the survey points was done using a military …

Topographic surveys of selected mine dumps near Silverton and Leadville, Colorado