New fieldwork investigating the provenance and stratigraphic setting of Triassic sedimentary rocks in the northern Cordillera focused on previously documented, but largely unstudied, exposures overlying the Yukon-Tanana, Slide Mountain and Cassiar terranes. We report on the lithologies observed and samples collected from the Sheldon Lake, Quiet Lake and Glenlyon map areas of Yukon, and McDame map area of northern British Columbia. Our research goal is to characterize sediment source regions in the Triassic and constrain early Mesozoic basin development in the northern Cordillera. We interpret the Triassic sedimentary evolution in Yukon and northern British Columbia to be intimately tied to collision of the Yukon-Tanana terrane with the ancient Pacific margin by closing of the Slide Mountain ocean. Our new samples collected from Middle to Late Triassic strata will further constrain that collisional event and add to the database that consists mainly of Early to Middle Triassic miogeoclinal rocks.