MICROMORPHOLOGICAL ANALYSIS OF A STRATIGRAPHIC PROFILE AT THE PALEOINDIAN LITHIC SITE OF BEAR CREEK, REDMOND, WA

Archaeological site 45KI839 contains Paleoindian lithic material with an upper limiting date of about 9840 calendar years ago. The site was identified at just over a meter below the modern surface in Redmond, WA in 2009 during a cultural resources assessment for the Lower Bear Creek Rehabilitation Project. Micormorphological analysis of a profile at 45KI839 was completed as part of later site testing efforts. The sampled profile consists of 30 centimeters of sediment composed of four discrete depositional units. The basal stratum of the profile consists of fluvially reworked glacial outwash. Finer-grained alluvium that relates to the transition from a paraglacial lacustrine shoreline to a wetland environment overlies the reworked outwash. The transitional alluvium contains lithic artifacts. Floodplain deposits of the Holocene emergent of Bear Creek overlie the transitional alluvium and appear to have supported a mosaic of riparian vegetation interspersed with wetlands. Diatomaceous earth that was deposited in a slackwater environment lies above the floodplain alluvium and peat. The slackwater environment may have been a result of tectonic subsidence, a change in Sammamish River morphology and subsequent flooding, or both. Bear Creek alluvium and modern fill complete the top of the stratigraphic sequence, but were not sampled. Micromorphology has allowed for detailed characterization of the bounding contacts between facies, especially those associated with the cultural materials. The results of this micromorphological analysis will be used to supplement the site formation history of 45KI839 that will be expanded upon during future data recovery investigations.