Climate Change Research Today is a free monthly online journal that collates and summarizes the latest research about Climate Change, including details on causes, effects, impact, facts, myths, information.

Younger Dryas "black mats" and the Rancholabrean termination in North America.

Haynes CV

Departments of Anthropology and Geosciences, PO Box 210030, University of Arizona, Tucson, AZ 85721, USA. cml@email.arizona.edu

Of the 97 geoarchaeological sites of this study that bridge the Pleistocene-Holocene transition (last deglaciation), approximately two thirds have a black organic-rich layer or "black mat" in the form of mollic paleosols, aquolls, diatomites, or algal mats with radiocarbon ages suggesting they are stratigraphic manifestations of the Younger Dryas cooling episode 10,900 B.P. to 9,800 B.P. (radiocarbon years). This layer or mat covers the Clovis-age landscape or surface on which the last remnants of the terminal Pleistocene megafauna are recorded. Stratigraphically and chronologically the extinction appears to have been catastrophic, seemingly too sudden and extensive for either human predation or climate change to have been the primary cause. This sudden Rancholabrean termination at 10,900 +/- 50 B.P. appears to have coincided with the sudden climatic switch from Allerød warming to Younger Dryas cooling. Recent evidence for extraterrestrial impact, although not yet compelling, needs further testing because a remarkable major perturbation occurred at 10,900 B.P. that needs to be explained.

Published 7 May 2008 in Proc Natl Acad Sci U S A, 105(18): 6520-5.
Full-text of this article is available online (may require subscription).

© 2004-2008 Climate Change Research Today. All Rights Reserved.