The Neruokpuk Formation in northeastern Alaska is a complex sequence of slightly metamorphosed rock units that lies below the major sub-Carboniferous unconformity. Cambrian fossils found in one of these units provide the first paleontologic evidence for the age of any part of the Neruokpuk in Alaska. The quartz semischists in the type area of the Neruokpuk near Lake Peters are considered to be Precambrian. Other fossiliferous strata lie unconformably above the schist and beneath the Cambrian beds. Sedimentologic, structural, or radiometric evidence indicates that both Taconic and Acadian orogenic episodes are represented in northeastern Alaska and northern Yukon.