The Karmutsen Group is very thick, and is neither highly metamorphosed nor strongly folded. About 18,000 feet of rocks, divided into five mappable units, are present. The group conformably overlies Triassic(?) argillites and flows and is conformably overlain by the Upper Triassic Quatsino Formation. The minimum depth of burial of the Karmutsen was 5,000 feet, and the maximum was never greater than 20,000. The volcanic activity in the geosyncline was cyclic, and each cycle can be divided into four parts: (1) volcanic quiescence and limestone deposition, (2) accumulation of close-packed pillow lavas, pillow breccias, and aquagene tuffs, (3) extrusion of thin-layered flows, and (4) extrusion of thick layered flows.