The western half of Quadra Island is underlain primarily by andesitic volcanic rocks of the Upper Triassic Karmutsen Formation which are overlain and bounded on the east by a northwest trending belt of Upper Triassic Quatsino Formation limestone, both of the Vancouver Group.

The Radium area is underlain by fractured and sheared chloritic andesitic and basaltic rocks of the Upper Triassic Karmutsen Formation. The flow rocks are commonly amygdaloidal and dip gently south and southwest at about 15 degrees. The amygdules are filled with chlorite, quartz, calcite and amphibole and locally chalcocite. Flows of amygdaloidal augite andesite contain disseminated chalcocite and a fractured, thinly banded, black siliceous carbonaceous rock that carries vanadium values. Sparsely disseminated chalcocite and some malachite staining are also present within this black rock which is also cut by minute quartz veinlets. Carnotite was reported in fractures within the volcanic rocks. An analysis of a carnotite sample taken in 1932 gave 24.5 per cent uranium and 21.1 per cent vanadium oxide (Geological Survey of Canada, Economic Geology 11). The occurrence of carnotite could not be confirmed during a field visit by the Geological Survey of Canada (Dr. R.T. Bell, personal communication).