Quaternary of Tierra del Fuego, Southernmost South America: an updated review

Abstract

The Quaternary of Tierra del Fuego is represented by glacial, glaciofluvial, glaciolacustrine, marine and aeolian deposits. Six drift units have been described, the oldest dating from the Late Pliocene: these are, starting from the oldest, the Río Grande, Sierra de los Frailes, Cabo Vírgenes, Punta Delgada, Primera Angostura and Segunda Angostura Drifts. Neoglacial and ?Little Ice Age? events are represented in cirques and higher mountain valleys. Marine deposits and raised beaches were formed during Middle Pleistocene, Late Pleistocene and Holocene interglacial stages. After the definitive ice-retreat (10 ka ago) vegetation changed from tundra and cold steppe to subantarctic forest environments. Marine deposits reflect also colder conditions than the present ones. Aeolian processes prevailed in northern Tierra del Fuego, where semiarid conditions and the frequent westerlies favoured the retransportation of finer materials coming from preexisting deposits. Before the opening of the Magellan Straits, earliest human colonization occurred in northern Tierra del Fuego ca. 11 ka BP, in tundra-like environmental conditions. Pedestrian hunters of camelids and foxes co-existed with Pleistocene fauna that became extint during Late Glacial-Earliest Holocene times. The steppe area (inland and Atlantic coast) was successively occupied since then until recent times. On the other hand, the Beagle Channel coasts were occupied since 6 ka BP by hunter-gatherer groups adapted to maritime littoral conditions. Finally, the easternmost area of the island was inhabited at least since 1.5 ka BP. The human settlements in these latter areas occurred under environmental conditions similar to the present ones, when the Fuegian forest was definitively established.