Sixtymile River alluvial deposits can be subdivided into four main types, on the basis of age and physiographic setting. These are pre-Reid and older; interglacial (prior to the McConnell glacial episode); modern (Holocene); and technogenic. All deposit types are placer-gold-bearing, and historically the most placer gold has been produced from modern (Holocene) deposits, followed by pre-Reid and older, interglacial, and finally, technogenic deposits.
Prospective placer gold exploration targets still exist and include 1) pre-Reid and older buried abandoned channels; 2) interglacial buried and/or abandoned alluvial terraces; 3) modern (Holocene) alluvial channels and gulches; and 4) technogenic deposits. Various exploration techniques can be used to evaluate these targets including airphoto interpretation, seismic and ground-penetrating radar surveys, electrical resistivity and magnetometer surveys, auger and reverse circulation drilling, and bulk sampling.
