HR: 11:05h
AN: PP42A-03    [Abstracts]
TI: Before and After the Younger Dryas: Chronostratigraphic and Paleoenvironmental Research at Arlington Springs, Santa Rosa Island, California
AU: * Johnson, J R
EM: jjohnson@sbnature2.org
AF: Santa Barbara Museum of Natural History, 2559 Puesta del Sol, Santa Barbara, CA 93105, United States
AU: Stafford, T W
EM: twstafford@stafford-research.com
AF: Stafford Research Laboratories, 200 Acadia Avenue, Lafayette, CO 80026, United States
AU: West, G J
EM: gjwest@dcn.davis.ca.us
AF: Department of Anthropology University of California, Davis, One Shields Avenue, Davis, CA 95616, United States
AU: Rockwell, T K
EM: trockwell@geology.sdsu.edu
AF: Department of Geology San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, United States
AB: To corroborate the age of 10,960 +/- 80 RCYBP (CAMS-16810) obtained on collagen from human bone from Arlington Springs, Santa Rosa Island, several seasons of fieldwork have been conducted at the site. This date, the oldest yet obtained for human skeletal remains in North America, indicates that Paleoamericans had reached the offshore Channel Islands by 13,000 CALYBP and confirms the use of watercraft along the Pacific coast of North America in Clovis times. The Arlington Springs field investigations have been undertaken as part of a research program to (1) identify the stratum from which the bones were originally discovered by Phil Orr in 1959, (2) establish the geological and chronostratigraphic context for the remains, (3) gather data for paleoenvironmental reconstructions, (4) assess geophysical techniques for detecting buried features at the site, and (5) obtain a series of deep sediment cores for further study. To date, twenty AMS radiocarbon dates from charcoal, humic acids, and marine shells in the various geological and cultural strata at the Arlington Springs locality have been obtained from samples collected during our fieldwork. These supplement six AMS dates that were derived from the human bone and associated materials in the soil matrix collected in 1960 by Orr. Our recently-collected samples corroborate that the age of the human bone dates no later than 13,000 CALYBP. An overlying, very dark soil layer, prominently visible in the side of Arlington Canyon, dates from the inception of the Younger Dryas at 12,900 CALYBP. Other, thinner, dark bands of sediment appear to be derived from fires and/or cienega/marsh deposits. In the stratum that contained the 13,000-year-old human bone, some small chert flakes have been recovered, indicating Paleoamerican cultural activities in the vicinity. In this cultural layer, as well as in the overlying dark soil of the Younger Dryas Period, there are abundant remains of an extinct Pleistocene deer mouse (Peromyscus nesodytes). Although our studies to date have not yielded well-preserved pollen in late Pleistocene soils at Arlington Springs, samples obtained from alluvial deposits at another locality upstream did yield abundant pollen indicating that a pine and cypress forest once existed on Santa Rosa Island at 10, 860 +/- 70 RCYBP (Beta- 161032). This date calibrates to 13,130 to 12,800 CALYBP or 12,270 to 12,650 CALYBP. The Arlington Canyon stratigraphy records major environmental and sedimentological changes that began after the inception of the Younger Dryas Period.
DE: 1105 Quaternary geochronology
DE: 1637 Regional climate change
DE: 1641 Sea level change (1222, 1225, 4556)
DE: 4901 Abrupt/rapid climate change (1605)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Joint Assembly