Tuesday, November 4, 2008

New Radiocarbon Dates for Burrell Orchard

This fall, I submitted one sample of bone and one of charred nutshell for radiocarbon dating. The bone sample came from unit 490N 509E and the nutshell was collected from beneath the siltstone slab feature (Fea. 08-02) in unit 500N 496E. The nutshell was found at the level of the chalkboard in the following image.

Each sample comes from secure contexts in the buried midden layers which contained the distinctive lanceolate-style points. The bone sample dated to 3,580 years ago (+/-40) which calibrates to a (two sigma) age between 2030 and 1780 BC. The nutshell was 3,950 years old (+/-40) with a calibrated (two sigma) date range of 2570 to 2340 BC. Each date places the prehistoric occupation of the site within the Late Archaic period, which in turn confirms that the lanceolate points do not belong to the late Paleoindian era (7000 to 10,000 BC) as concluded by previous researchers. I plan to submit a few more samples for dating, but I feel that these dates are accurate.

That fact that the calibrated date intervals are separated by about 300 years may indicated that the site was revisited over several centuries by prehistoric Native Americans. This seems to be a likely conclusion.