TRANSGRESSIONS - RETHINKING BERINGIAN GLACIATION

Citation
Ba. Hughes et Tj. Hughes, TRANSGRESSIONS - RETHINKING BERINGIAN GLACIATION, Palaeogeography, palaeoclimatology, palaeoecology, 110(3-4), 1994, pp. 275-294
Citations number
154
Language
INGLESE
art.tipo
Review
Categorie Soggetti
Paleontology
ISSN journal
0031-0182
Volume
110
Issue
3-4
Year of publication
1994
Pages
275 - 294
Database
ISI
SICI code
0031-0182(1994)110:3-4<275:T-RBG>2.0.ZU;2-W
Abstract
The purpose of this investigation is to encourage a fresh look at Plei stocene Beringia. Heretofore, flooding of Bering Strait has been cited as the only barrier to migration, with marine sea transgressions bein g a ''sea gate'' that closed off migration during glacial interstadial s and interglaciations. However, the possibility exists that glacial a dvances were also barriers, with marine ice transgressions being an '' ice gate'' that closed off migration during glacial stadials and glaci al maxima. This possibility proceeds from the Marine Ice Transgression Hypothesis (MITH), which states that marine ice sheets form on the br oad Arctic continental shelf of Northern Hemisphere continents when se a ice thickens, grounds and domes in shallow water, and then transgres ses landward as continental ice sheets and seaward as floating ice she lves (Hughes, 1987). Landward transgression is onto coastal lowlands. During Pleistocene glaciations, a marine ice sheet extending from Spit sbergen to Greenland may have transgressed the circumpolar continental landmass at its lowest and narrowest gap, central Beringia, and calve d into the Pacific Ocean. Four models of Beringian glaciation are pres ented, based on the distinction between marine glaciation and highland glaciation. Central Beringia was glaciated only in highlands in the t raditional model (Hopkins et al., 1982), was also glaciated by a self- sustaining ice shelf floating over the deep ocean basins of the Bering Sea in the model by Grosswald and Vozovik (1984), was glaciated by a marine ice sheet that covered highlands, the continental shelf, and su pplied the ice shelf in a model for maximum Pleistocene glaciation, an d was glaciated by a marine ice sheet in the Chukchi Sea that merged w ith highland glaciers, transgressed the continental shelf of the weste rn Bering Sea, and calved into the southern Bering Sea along the edge of the continental shelf in a model for the last glaciation. Field tes ts are suggested to assess the viability of these four models. The fir st model is already established for highland glaciation in Alaska, but less established in Siberia. The last model should be the easiest to evaluate for marine glaciation. The last model limits human migration across the Beringian land bridge to brief intervals between stadials a nd interstadials of the last glaciation cycle, when bath the ice gate and the sea gate were opened to human migration. This model can influe nce the sea change now underway among Quaternary scientists studying p eopling of the Americas, based on the archaeological, linguistic and e thnic diversity among native American populations.