Southern Gravina Island is underlain by an assemblage of undivided Silurian or Ordovician metamorphosed bedded and intrusive rocks; a stock and associated dikes of Silurian trondhjemite that cuts the metamorphic assemblage; and a sequence of Upper Triassic carbonate, clastic, rhyolitic, and basaltic strata that unconformably overlies the older rocks (Berg, 1973, 1982; Berg and others, 1988). The rocks are complexly folded and are cut by high-angle faults and by low-angle thrust faults. In many places, the Triassic rhyolite and the rocks beneath it are permeated by microscopic particles of hydrothermal hematite, giving them a pink, purple, or red hue (Berg, 1973, p. 14).

Wright and Wright (1908, p. 139) describe the Buck prospect only as a wide quartz vein, in altered quartzite and schist, that reportedly assayed well in Cu and Au. Maas and others (1995, p. 229) describe the North Paula deposit as seams and clasts of chalcopyrite and pyrite in silicified breccia in metavolcanic hostrock. Their best sample assayed 1.1% Cu across a 6-foot-wide section of the deposit. Workings, probably mainly dating to the early 1900s, included a 12.5-foot adit, a flooded shaft, and several trenches.