CO-SEISMIC ACTIVITY AND ARCHAEOLOGY IN SOUTHERN BIRCH BAY, WASHINGTON

Recent geological studies, combined with separate archaeological investigations, indicate that co-seismic activity affected people’s use of Birch Bay’s landscape over the last 3,000 years, sometimes immediately. Subsidence and uplift altered southern Birch Bay’s landscape three times during the past 1,700 years. This adds context to archaeological dates. An upland shell midden by Terrell Creek was dated to approximately 3,125 yr BP. The creek subsided next to it between 1,390 and 1,290 yr BP. Charcoal from the hearth in the possibly resultant beach berm dated to approximately 1285 yr BP. As the berm grew, so did land use. Berm midden revealed dates between around 900 and 500 yr BP. To the north, uplift occurred twice: (1) between 1,710 and 1,530 yr BP. and (2) between 1,280 and 1,079 yr BP. Inland upland shell midden in the area predated the uplift at around 3,180 yr BP. Archaeological dates by the shore ranged after the land movement between approximately 1,000 and 285 years ago. This presentation summarizes preliminary comparisons between the geological and archaeological findings.