Tofino Basin comprises a Tertiary forearc assemblage of clastics sediments in excess of four kilometres thick that occupies an area of about 7500 km 2 on the continental margin of western Vancouver Island. The strata are characterized by an overall low total organic carbon content and low hydrogen index. The organic matter is predominantly Type III and petrographically is comprised mainly of finely divided vitrinite. The richest source rocks are Miocene and Oligocene strata encountered in the D-14 and I-87 wells, but even these are poor source rocks as traditionally defined. Pliocene and younger strata are immature with respect to the oil window, whereas Lower Miocene and Oligocene strata are mature. Tofino Basin has little liquid hydrocarbon potential.