A 9700-Year-Old Shell Midden on San Miguel Island, California. (News & Notes)
Erlandson, Jon M., Rick, Torben C., Antiquity
California's Channel Islands, never connected to the mainland and clearly settled by boat, have produced evidence of early maritime activity dating between 12,000 and 13,000 years ago (cal BP). A recent search for early sites on San Miguel Island focused on reconnaissance of the Simonton palaeosol (Johnson 1972), a prominent stratigraphic marker underlying Holocene dunes. Geological and archaeological [sup.14]C dates suggest that the Simonton soil marks a period of landform stability dating between about 17,000 and 7500 years ago. Eroded soil remnants are exposed in many sea cliff and gully profiles, while others are buried under Holocene dunes. Near a small spring in Busted Balls Cove, we recently identified a 9700-year-old shell midden--one of the earliest from the Pacific Coast of North America.
In a 1966 site record, Kritzman described SMI-522 as `a campsite (probably permanent)' exposed for about 9 m along the sea cliff, containing black abalone, California mussel and owl limpet shells and one bone `gouge'. In 2000, Erlandson and Don Morris visited SMI-522 and found remnants of a dense shell midden up to 30-40 cm thick eroding from a dune soil just above the Simonton soil. The extent and density of this site, the largest and deepest of 11 small Early Holocene shell middens documented in the vicinity, along with what we knew about the chronology of the Simonton soil and overlying dunes, led us to hypothesize that the site was occupied after 7500 years ago.
To test this hypothesis, we submitted two [sup.14]C samples from SMI-522 for dating. An AMS date of 9450 [+ or -] 70 RYBP (OS-27943) was obtained from a well preserved California mussel shell from the base of the midden, with a calibrated intercept of 9830 cal BP (1[sigma] range = 10,250-9720 cal BP; CALIB 4.3). A conventional date on a black abalone shell from the same provenience confirmed the site antiquity, with an uncorrected age of 9220 [+ or -] 120 RYBP (Beta-151616) and a calibrated intercept of 9610 cal BP (9830-9160 cal BP). Averaging these dates suggests SMI-522 was occupied about 9700 years ago, but the age may be 100-200 years greater since the regional reservoir effect appears largely to have disappeared between 8500 and 10,000 years ago (Kennett et al. 1997).
In 2001, we returned to SMI-522 to salvage preliminary data. We conducted a close-transect (c. 1 m) surface collection and screened sediments eroded from sea cliff exposures. The artefacts collected include a large serrated point or knife fragment, two bone fish gorge (bipoints) fragments, a sandstone grinding slab, two flaked core tools made from metavolcanic cobbles, several expedient flake tools and pieces of chipped stone debitage. …