An erosional outlier of Quatsino limestone is in conformable contact with undifferentiated Karmutsen basalt and andesite, all of which has been intruded by a northwest trending body of coarse-grained biotite quartz monzonite. Thin sills and dykes of fine-grained diabase cut the limestone but were not seen to cut the monzonite. Thin skarns form along the volcanic limestone contact.