New methods for sourcing fine-grained volcanic artifacts in the Salish Sea: a holistic approach

This investigation presents an alternative method to sourcing fine-grained volcanic (FGV) artifacts from the Salish Sea in western Washington. Past sourcing strategies have utilized geochemical methods focusing on the trace element composition of artifacts. This research has verified the extensive use of the only known geologic source (Watts Point, B.C.) but has not yet identified other geologic sources for artifacts from the Salish Sea. The research presented herein develops a three-tiered holistic approach to sourcing FGV artifacts from the region. The addition of whole rock major element and mineralogical analyses in conjunction with trace element analysis develops a more accurate method to sourcing FGV artifacts. Artifacts from nine sites in western Washington (45WH1, 45WH4, 45WH17, 45WH34, 45WH55, 45SK46, 45WH300, and three sites from the North Cascades National Park) are compared with geologic samples from nine locations in the North Cascades and Salish Sea using this three-tiered holistic approach to sourcing. Using this methodology, 17 new unknown sources are identified; these sources represent many types of FGVs (dacite, andesite, rhyolite, and trachydacite). Of the artifacts, 72% are composed of dacite while the remaining 28% are other various types of FGVs. Of the dacite artifacts only about half come from Watts Point, showing that native people were not dependent on Watts Point as a source for their tool stone and had access to many other FGV sources.