No abstract

In 1980 a large proboscidean femur, probably Mammuthus sp., was found in situ in a bluff exposure at the mouth of the Tyone River in the northwestern part of the Copper River Basin, Alaska. The regional setting, stratigraphy, radiocarbon chronology, flora, and implications of the fossil locality, which represents the first documented occurrence of Pleistocene terrestrial mammalian fauna in southern Alaska, are described. Radiocarbon dates and stratigraphic relations at the site indicate that the sediments containing the fossil accumulated during the transition from interstadial to glacial conditions during terminal middle Wisconsin time. During this interval the immediate vicinity was unforested and large areas of south-central Alaska may have been available for faunal and possibly human habitation. This documented find, dated at 29,450 ± 610 14C yr B.P., extends the known range for Pleistocene mammals and possibly steppe-tundra conditions south-ward at least 150 km, and suggests that mountain passes through the Alaska Range to the north were ice free during the last part of the middle Wisconsin interstadial.

This atlas illustrates the interrelationships among the landforms, soils and vegetation of a portion of the Arctic Coastal P lain of Alaska. The Prudhoe Bay region is dominated by an alkaline peaty coastal tundra, a type that has not been intensively studied. Forty-two vegetation communities, thirteen major landforms, and eight soil types are described. Several of the plant communities and one soil, the Pergelic Cryoboroll, have not been described previously. The vegetation is discussed with respect to three important gradients: temperature, soil pH and soil moisture. Other aspects of the Prudhoe Bay environment, including geology, permafrost, and winter and summer climate, are discussed and illustrated. Also included are historical descriptions of the development of the oilfield and of selected scientific investigations in the Alaskan Arctic. Master maps present the landforms, soils and vegetation of a 145-km 2 portion of the oilfield road network at a scale of 1:1 2,000. Derived geobotanical special purpose maps, useful for land-use planning and management of the ecosystem, are explained and several examples are shown for a 3.6-km 2 portion of the oilfield. Cover: The lillie Putuligayuk River. Meandering tun• dra streams, low-centered polygons, high• centered polygons, onented thaw lakes, and dramed thaw lake basms are all characteristic features of the landscape withm the Prudhoe Bay regeon Photograph by D A.