The Anvil district contains the most westerly off-shelf basinal facies of the Cordilleran miogeocline, a prism of sedimentary rocks of Precambrian to Jurassic age deposited along the relatively stable continental margin of western North America. The district is part of Selwyn basin, a large area of central Yukon in which deep water clastic rocks, chert, and minor carbonate accumulated along the ancient North American continental margin during Neoproterozoic and early Paleozoic time (Gabrielse, 1967).
