Upper Jurassic to Lower Cretaceous Bowser Lake Group sediments are intruded by the Early Tertiary age Seven Sisters stock which forms the core of the Seven Sisters Peaks. The sediments are mainly siltstone and greywacke with minor conglomerate, greenstone and rhyo- lite. Near the stock, they are sharply crenulated and deformed. The stock is largely granodiorite with lesser granite and diorite. Quartz feldspar porphyry is gradational with the intrusive and forms dykes cutting the sediments. Aplitic dykes extend from the intrusive into the sediments.

Mineralization in the north central cirque area consists of widely spaced fractures with quartz, molybdenite, and minor chalco- pyrite and scheelite in granodiorite. A talus sample with rusty pyrrhotite taken from below a gossan zone assayed 0.171 grams per tonne gold, 49.71 grams per tonne silver, 0.38 per cent copper, 0.44 per cent lead, 3.1 per cent zinc, 0.01 per cent molybdenum (MoS2) and 0.02 per cent tungsten. A one kilometre long, north-northeast trending geochemical high returned assays up to 0.08 per cent copper, 1.12 per cent lead, 0.13 per cent zinc, 0.32 per cent molybdenum, 37 grams per tonne silver and 0.03 per cent tungsten. Talus samples carrying massive pyrrhotite with chalcopyrite and scheelite occur 1.5 kilometres to the east and returned values of 1.22 per cent copper, 0.010 per cent Mo, 0.57 per cent tungsten and 16.1 grams per tonne silver (Assessment Report 8467).