AbstractA recently driven sewer tunnel west of Blackburn has shown the presence of a thick turbidite sequence between theR. gracileandR. bilingueGoniatite Bands. Above theR. bilingueBand, turbidites pass up through delta slope deposits into delta top fluviatile sandstones, derived from the northeast. The section provides evidence for the westward limit of advance of the pre‐R. gracileKinderscoutian delta slope and also enables a more accurate R2isopachyte map to bc draw