Eagle Creek is a 7.5-mile-long tributary to the East Fork Chistochina River. The mouth of the creek is on the Gulkana quadrangle. The Eagle Creek mine is a few hundred feet east of the center of section 10, T. 14 N., R. 5 E., Copper River Meridian (Moffit, 1944; Richter and others, 1977). (A feature shown in the SE1/4 section 34, T. 15 N., R. 5 E., Copper River Meridian, on the topographic map of the Mount Hayes A-1 quadrangle is almost certainly a landslide, not tailings [see Richter and others, 1977].)

Bedrock in the upper part of Eagle Creek consists of limestone, argillite, chert, and porcellanite (Richter, 1967; Richter and others, 1977); the lower canyon and lowlands below the canyon are cut in volcanic flows, clastic debris, and tuff that is locally pyritic and silicified (Moffit, 1944; Richter and others, 1977). Bedrock at the mine consists mainly of andesitic volcanic rocks of the Tetelna Volcanics of Pennsylvanian age. The Tetelna is overlain by volcanic and impure limy rocks of the Slana Spur Formation of Pennsylvanian and Permian age. Up the canyon, the Slana Spur Formation is successively overlain by Eagle Creek Formation of Permian age and the Nikolai Greenstone of Late Triassic age. Small granitic plutons are present in upper Eagle Creek. The placer mine site is just west of the type area for the Slana Spur Formation (Richter and Dutro, 1975). The placer mine is in valley alluvium of Holocene age. The area is extensively mantled by glacial drift of Wisconsin age.