Pacific Section AAPG Convention

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Petrographic Analysis And Provenance Of Ground Stone Tools From Northern Channel Islands And Coastal Southern California


Eighteenth century Spanish explorers observed and documented the exchange of tools and goods between various Chumash tribes in Southern California. Mortar, pestle, and matate samples from documented archeological sites on the northern Channel Islands and within the northern California Bight Regions consist of a range of lithologies, including sandstone, volcanic rocks, and sedimentary concretions. By identifying where stone tools were produced in relation to the locations where they were ultimately found, our study attempts to provide constraints on the reconstruction of trade relationships of the indigenous people. Petrographic analyses and detailed descriptions on a sample set of these tools will aid in determining the correlative source lithologies from the area, providing insights to the extent of Chumash trade networks within the late Holocene. Exposures of volcanic rocks and resistant sandstones located throughout the northern Channel Islands are known resources and stone tool production sites used by the Chumash. Archaeologists and geologists have rapidly progressed the understanding of many cultures throughout the world by determining provenance of implement artifacts. The Chumash have an extensive history, and by applying petrographic analysis and detailed descriptions of these samples, we can further grasp the culture of these prominent and important peoples.