Surficial-geologic map of the Eagle A-1 Quadrangle, Fortymile mining district

Preliminary Interpretive Report 2002-1C, Surficial-geologic map of the Eagle A-1 Quadrangle, Fortymile mining district, provides 1:63,360-scale geologic mapping of the Eagle A-1 Quadrangle. The area is part of the 100-year old Fortymile mining district and is located in eastern Alaska near the Alaska-Yukon border. This map illustrates the distribution of a variety of unconsolidated deposits and undifferentiated bedrock in the Eagle A-1 Quadrangle, Fortymile mining district. It was prepared by the interpretation of 1:63,360-scale, false-color, infrared aerial photographs taken from July 1978 through August 1981 and is locally verified by ground observations during field visits.The results should be considered reconnaissance in nature. The dominant unconsolidated deposit is colluvium, which mantles most surfaces other than the tops of ridges and those areas immediately adjacent to streams. Three levels of stream terrace can be traced along major drainages at elevations of roughly 200, 100, and 30 meters above modern streams. A fourth low terrace is limited to the southwest part of the map area. Pleistocene mammalian remains have been recovered from ice-rich organic silt and muck overlying placer gravels in many valleys. The complete report, geodatabase, and ESRI fonts and style files are available from the DGGS website: http://doi.org/10.14509/22081.