This map of the Yakataga district is one of five maps at the same scale, showing the geology of the Gulf of Alaska Tertiary province (see index map). In this province, an accurate belt more than 300 miles long and 2 to 40 miles wide, sedimentary rocks of Tertiary age are exposed or inferred to underlie lowland areas covered by Quaternary unconsolidated deposits or ice (Miller, Payne, Gryc, 1959, p. 37-47). Field studies were carried out in the province intermittently from 1944 to 1960, under the Geological Survey's program of petroleum investigations in southern Alaska.