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Geology; January 2004; v. 32; no. 1; p. 58; DOI 10.1130/G19957.1; 2 figures; Data Repository item 2004001. 5
Prolonged wet period in the southwestern United States
through the Younger Dryas
Victor J. Polyak*
Jessica B.T. Rasmussen
Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, USA
The Younger Dryas was one of the more dramatic climatic transitions ever recorded.
How these types of climatic shifts are expressed in continental interiors is of primary
scientific interest and of vital societal concern. Here we present a speleothem-based ab-
solutely dated record (using uranium-series data) of climate change for the southwestern
United States from growth chronology of multiple speleothems. The stalagmite growth
represents the onset of wetter climate (12,500 yr B.P.) soon after the start of the Younger
Dryas; the wetter climate persisted a millennium beyond the termination of the Younger
Dryas. This wet cycle is likely related to a more southern positioning of the polar jet
stream in response to cooler Northern Hemisphere climate. The end of the wet period
coincides with the peak of the Holocene summer insolation maximum ca. 10,500 yr B.P.
The A° llerød (prior to the Younger Dryas), which corresponds to Clovis occupation in the