Artifacts of Exchange: A Multiscalar Approach to Maritime Archaeology at Elmina, Ghana

This dissertation focuses on the excavation and interpretation of two European ships discovered at Elmina Ghana, the coastal site of the first and largest European fort in sub-Saharan Africa. Discovered in 2003, the first vessel, located 1.5 miles offshore of the castle, is largely comprised of remnants of cargo exposed on the seafloor. European trade wares recovered from the site suggest a mid-seventeenth century vessel, most likely of Dutch origin. AMS radiocarbon dates obtained from several fragments of wood recovered in cores taken at the site support this assumption. The second vessel was discovered by accident during the 2007 dredging of the Benya River, a small lagoonal system that empties into the sea at Elmina. Largely destroyed during the operation, identifiable remains included fifteen timbers and three cannon. Dendrochronology and ship construction techniques indicate the remains to be those of an early eighteenth century Dutch vessel. The two ships thus represent different time periods, historical settings, and archaeological contexts. Yet, the value of both to the reconstruction of the West African past lies with both their local and global contexts. On one hand, they represent unique insight into the construction of the European ships that traded on the coast and their cargoes. On the other, data on their cargoes and associated artifacts provide information on trade and exchange in a world area that has received little attention from underwater archaeologists. Often times the work of underwater archeologists has been criticized for producing particularistic interpretations lacking wider context and theoretical synthesis. Shipwrecks were investigated for their intrinsic value, an emphasis was given to spectacular objects, and the literature resulting from these excavations was primarily descriptive in nature. In my dissertation I argue that such deficiencies can be countered by incorporating a theoretical framework which engages both the nomothetic and particularistic. To a large extent, the questions that confront studies of shipwrecks are problems of scale: how do we move from the minutia of cargoes and the specificity of an event to wider social processes? Methodologically, how do we decide what data are to be collected and evaluated? Conceptually, what is it that we seek to understand from our studies? Grappling with these questions I draw upon the methodological and conceptual insights afforded by microhistory, the Annales school, and Braudel\u27s three scales of history. I propose a dialectical interpretation of shipwrecks attentive to the intersection of local patterns and global forces in the shaping of history. Utilizing macro-scale historical generalizations (i.e. trade patterns, cargoes, ship, and artifact characteristics) archaeologists can interpret, and identify the micro-scale event (nationality, date, vessel name, wrecking event). Once done, the particulars of the site in turn afford means of understanding large-scale social processes

Temporal geochemical variations in lavas from Kīlauea's Pu‘u ‘Ō‘ō eruption (1983–2010): Cyclic variations from melting of source heterogeneities

[1] Geochemical time series analysis of lavas from Kīlauea's ongoing Pu‘u ‘Ō‘ō eruption chronicle mantle and crustal processes during a single, prolonged (1983 to present) magmatic event, which has shown nearly two-fold variation in lava effusion rates. Here we present an update of our ongoing monitoring of the geochemical variations of Pu‘u ‘Ō‘ō lavas for the entire eruption through 2010. Oxygen isotope measurements on Pu‘u ‘Ō‘ō lavas show a remarkable range (δ^(18)O values of 4.6–5.6‰), which are interpreted to reflect moderate levels of oxygen isotope exchange with or crustal contamination by hydrothermally altered Kīlauea lavas, probably in the shallow reservoir under the Pu‘u ‘Ō‘ō vent. This process has not measurably affected ratios of radiogenic isotope or incompatible trace elements, which are thought to vary due to mantle-derived changes in the composition of the parental magma delivered to the volcano. High-precision Pb and Sr isotopic measurements were performed on lavas erupted at ∼6 month intervals since 1983 to provide insights about melting dynamics and the compositional structure of the Hawaiian plume. The new results show systematic variations of Pb and Sr isotope ratios that continued the long-term compositional trend for Kīlauea until ∼1990. Afterward, Pb isotope ratios show two cycles with ∼10 year periods, whereas the Sr isotope ratios continued to increase until ∼2003 and then shifted toward slightly less radiogenic values. The short-term periodicity of Pb isotope ratios may reflect melt extraction from mantle with a fine-scale pattern of repeating source heterogeneities or strands, which are about 1–3 km in diameter. Over the last 30 years, Pu‘u ‘Ō‘ō lavas show 15% and 25% of the known isotopic variation for Kīlauea and Mauna Kea, respectively. This observation illustrates that the dominant time scale of mantle-derived compositional variation for Hawaiian lavas is years to decades

Wide-Area Debris Field and Seabed Characterization of a Deep Ocean Dump Site Surveyed by Autonomous Underwater Vehicles.

Disposal of industrial and hazardous waste in the ocean was a pervasive global practice in the 20th century. Uncertainty in the quantity, location, and contents of dumped materials underscores ongoing risks to marine ecosystems and human health. This study presents an analysis of a wide-area side-scan sonar survey conducted with autonomous underwater vehicles (AUVs) at a dump site in the San Pedro Basin, California. Previous camera surveys located 60 barrels and other debris. Sediment analysis in the region showed varying concentrations of the insecticidal chemical dichlorodiphenyltrichloroethane (DDT), of which an estimated 350-700 t were discarded in the San Pedro Basin between 1947 and 1961. A lack of primary historical documents specifying DDT acid waste disposal methods has contributed to the ambiguity surrounding whether dumping occurred via bulk discharge or containerized units. Barrels and debris observed during previous surveys were used for ground truth classification algorithms based on size and acoustic intensity characteristics. Image and signal processing techniques identified over 74,000 debris targets within the survey region. Statistical, spectral, and machine learning methods characterize seabed variability and classify bottom-type. These analytical techniques combined with AUV capabilities provide a framework for efficient mapping and characterization of uncharted deep-water disposal sites

Source materials for inception stage Hawaiian magmas: Pb-He isotope variations for early Kilauea

http://www.godac.jamstec.go.jp/darwin/cruise/kairei/kr98-09/