New insights about the construction and use of shell mounds from the geochemical analysis of mollusks: an example from the greater San Francisco Bay

Envisioning Colonial Landscapes Using Mission Registers, Radiocarbon, and Stable Isotopes: An Experimental Approach from San Francisco Bay

“…As one example of an "integrated approach" to the archaeology of prehistory and history espoused by Lightfoot (1995), the following exploratory study compares seasonal inferences from baptism records compiled at Spanish missions to geochemical and radiometric data derived from archaeological specimens from the CA-MRN-114 shellmound. Finstad et al (2013). b Schweikhardt et al (2011).…”

“…Since the pioneering seasonality research conducted by Epstein et al (1951Epstein et al ( , 1953 and Shackleton (1973), stable isotope analysis of marine shells has been an increasingly important component of the archaeological toolkit (Culleton et al 2009;Eerkens et al 2013;Eerkens et al 2014;Finstad et al 2013;Jones and Kennett 1999;Jones et al 2008;Kennett 2005;Schweikhardt et al 2011). Much of this recent research focuses on shellmounds, which for the San Francisco Bay area are best known for long records of prehistoric occupation that often extend several hundred years or more and have been recognized for decades as important sources of environmental and ecological data and as testing grounds for new archaeological field techniques (Cook and Treganza 1947;Gifford 1946;McGeein and Mueller 1955;Meighan 1950;Meighan et al 1958aMeighan et al , 1958bTreganza and Cook 1948).…”

“…In viewing two primary sites of Coast Miwok missionization-the Spanish missions at San Francisco and at San Rafael-as "ecological resources" (Ricklis 1996), I develop an experimental approach that compares seasonal interpretations from mission baptism records to stable isotope data and radiocarbon dates collected from a Late period Phase 2 (A.D. 1500-1800) shellmound (CA-MRN-114) on the Marin Peninsula. To do so, I use a methodology developed by Schweikhardt (2007) and subsequently applied by Finstad (2009), Schweikhardt et al (2011), andFinstad et al (2013) that subjects archaeological mussel (Mytilus spp.) shells collected from shellmounds to elemental and isotopic analyses to calculate the season of death of the mussels and to infer patterns of seasonal residence and mound construction by Native Americans.…”

“…More recent studies employ stable isotope analysis to detail the variable timing and seasonal accretion of shellmound deposits throughout the San Francisco Bay (Table 1). Finstad et al (2013), for instance, revisit the questions of when and how shellmound clusters were inhabited. Revising an earlier interpretation that mound clusters represented seasonally vacant ceremonial centers (Luby et al 2006), isotopic and radiometric data collected from two shellmounds in an East Bay mound cluster-one large mound (CA-CCO-295) and a smaller mound (CA-CCO-290)-instead suggest contemporaneous, year-round, and late occupations extending into the late 1700s and up to Spanish colonization (Finstad et al 2013(Finstad et al :2654.…”

“…Temperature and salinity shifts are reflected in oxygen isotope ratios and relative proportions of magnesium and calcium (Schweikhardt et al 2011(Schweikhardt et al :2304). As mussels grow, they add calcite material to the edges of their shell, "thereby incorporating seawater chemistry and recording there the last environmental conditions they experienced immediately prior to harvest" (Finstad et al 2013(Finstad et al :2651. The theoretical and methodological frameworks for shellfish isotopic analysis of archaeological mussel shell used in this study closely follow geochemical sampling and analytic standards developed by Schweikhardt (2007) and applied by Finstad (2009), Schweikhardt et al (2011), and Finstad et al (2013).…”