At the Uchucklesit Inlet occurrence, a limestone band of the Upper Triassic Vancouver Group, Quatsino Formation extends northward from the northwest shore of Uchucklesit Inlet for 5 kilometres to the southeast shore of Henderson Lake, 30 kilometres southwest of Port Alberni. The band is segmented by several west-northwest trending cross faults. The unit is underlain by volcanics of the Upper Triassic Vancouver Group, Karmutsen Formation and overlain by volcanics and sediments of the Lower Jurassic Bonanza Group.