The region is underlain by the Paleozoic and/or Mesozoic Wark Gneiss and basaltic to rhyolitic volcanics of the Lower Jurassic Bonanza Group. A stock of the Late Devonian Saltspring Intrusive Suite (formerly called the Saltspring Intrusions) consisting of metagranodiorite, metaquartz porphyry and quartz sericite schist occurs nearby to the southeast.
A discontinuous carbonate horizon extends from Cordova Bay northwestward across Saanich Inlet to the east shore of Shawnigan Lake. Its general fine-grained, massive character and its associa- tion with greenstones and magnetite-sulphide skarns suggests that this horizon is correlative with the Upper Triassic Quatsino Formation, Vancouver Group.
The Wark Gneiss has given a few potassium-argon ages ranging from 131 to 182 Ma indicating the latest metamorphism to be of Jurassic age. Discordant zircon dates have yielded indefinite Paleozoic ages. The protolith of the Wark Gneiss may have been composed of rocks of the Sicker Group and Karmutsen and Quatsino formations (Vancouver Group). The Wark Gneiss comprises mainly massive and gneissic metadiorite, metagabbro and amphibolite.
At least 10 principal skarn showings occur along an 800-metre section of the discontinuous limestone band just north and west of Oliphant Lake. The band here is about 300 metres wide. The deposits occur as lenses and fracture fillings in limestone or limy bands near greenstone or diorite and consist of two intermingled or compliment- ary types: (a) massive pyrrhotite and pyrite with minor chalcopyrite in skarn, and (b) magnetite in skarn. The showings all seem to be about a metre or so in width and up to several metres in length. The skarn minerals present are garnet, diopside and epidote.
Some of the showings have been worked since the turn of the century. At least 3 adits, 3 shafts and several opencuts have been excavated. A sample taken at showing Number 9 assayed 2.74 grams per tonne gold, 24.00 grams per tonne silver, 2.38 per cent copper and 57.33 per cent iron. Most samples taken, however, assayed nil or trace gold and silver and less than 0.5 per cent copper (Property File - Aho, 1961, page 14).
