Cave, a lava tube cave on St. Paul Island in the Pribilofs, has recently produced a mid-Holocene vertebrate faunal assemblage including woolly mammoth, polar bear, caribou, and Arctic fox. Several dates on the mammoth remains converge on 5700 14C yr BP. These dates, ~ 2300 yr younger than mammoth dates previously published from the Pribilof Islands, make these the youngest remains of proboscideans, and of non-extinct Quaternary megafauna, recovered from North America. Persistence of mammoths on the Pribilofs is most parsimoniously explained by the isolation of the Pribilofs and the lack of human presence in pre-Russian contact times, but an additional factor may have been the local existence of high-quality forage in the form of grasses enriched by nutrients derived from local Holocene tephras. This interpretation is reinforced by stable carbon and nitrogen isotope values obtained from the mammoth remains. The endpoint of mammoth survival in the Pribilofs is unknown, but maybe coterminous with the arrival of polar bears whose remains in the cave date to the Neoglacial cold period of ~ 4500 to 3500 14C yr BP. The polar bear record corroborates a widespread cooling of the Bering Sea region at that time.
The temperate Laurentide Ice Sheet exhibited a grounded calving front as it retreated across coastal Maine about 14,000 to 12,500 B.P. The terminus resembled a modern tidewater glacier as the ice retreated through 0 to 80-m-deep water in the isostatically depressed region.Many areas of coastal Maine exhibit structural features that affect Holocene coastal landforms. In southwestern Maine, these northeast-southwest-trending strike valleys and ridges formerly exerted strong control on glacial retreat rates and deposition along the ice margin. Deposition of small DeGeer-type moraines and larger, stratified, subaqueous moraines/fans occurred where structural ridges slowed ice retreat. As ice retreat continued landward into even shallower water, the retreat rate was slowed by structural ridges, and deposition prograded to sea level, producing ice-contact beheaded deltas. In some areas, bedrock ridges underlie Gilbert-type deltas, while in other situations, ridges protruded above sea level as hills or islands. Eskers connected to the proximal sides of the deltas indicate that ridges deflected subglacial water to the surface in these locations. to the Androscoggin River basin (Fig.
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