Santa Cruz Island Reserve

19 Aug, 03 AM - 21 Aug, 08 AM

Reconstructing Prehistoric Plant Use on Santa Cruz Island Introduction Within the Santa Barbara Channel region, current understanding of the use of plant food resources is largely based on assumptions from ethnographic records and a few kinds of artifacts associated with food processing. The proposed study would generate evidence to challenge or confirm these assumptions through the combined analysis of both macrobotanical remains (e.g., charred seeds), and microbotanical remains (both starch grains and phytoliths) extracted from the surface of ground stone artifacts. While certain resources (e.g., nuts and seeds) are likely to preserve as carbonized macrobotanicals, others (e.g., grasses, roots, tubers) can only be recovered through microbotanical analysis. Therefore, this combined approach allows for the recovery of a much wider range of plant taxa used as food resources, and thus for a fuller understanding of the prehistoric diet. The goals of this project are (1) to recover archaeobotanical data from two middle Holocene (6,650 to 3,350 RYBP) sites in Santa Cruz Island’s Central Valley (within UC’s Santa Cruz Island Reserve), and (2) to expand the existing comparative collection of California native plants housed at UCSB, in order to facilitate species identifications for this, and future, regional studies. Statement of Research Design The long span of prehistoric occupation and the high density of archaeological sites, combined with intact stratigraphy and high levels of preservation of prehistoric remains, make Santa Cruz Island an ideal place to conduct archaeological research. Until recently, much of this research has focused on large, coastal sites and on the importance of marine resources; while comparatively little research has addressed interior sites and terrestrial resources. As the largest and most terrestrially diverse of the Channel Islands, the interior of Santa Cruz Island hosts a wealth of resource patches that may contribute to settlement decisions. In particular, the Central Valley is the most productive watershed on Santa Cruz Island (Kennett 2005), and home to an abundance of economically valuable plant resources. Additionally, its central location allows access for foraging trips along the north ridge, south ridge, and isthmus, and to the east and west ends of the island (see figure 1). Kennett (2005:129) notes that, “ephemeral ‘interior residences’ may be logistical encampments that were used periodically to collect and process plant foods (seeds and bulbs) from surrounding environs.” Indeed, as noted by Perry and Delaney-Rivera (2011:117), “the current data suggest that the Central Valley was occupied on a regular basis as part of the seasonal foraging rounds of middle Holocene populations because of the intersection of desirable resources, routes, and possibly even weather conditions.” As the first study to combine macro and micro-botanical analysis, this project will be uniquely qualified to address exactly which terrestrial resources humans were accessing in the interior of Santa Cruz Island. The presence of species from higher elevations (e.g., pine nuts), or even non-native mainland species (e.g., walnut, as found by Martin and Popper 2001), could shed light on foraging patterns or trade, respectively. By targeting sites dating to the middle Holocene (7,500 - 3,500 years ago), I hope to contribute terrestrial data from a time period that remains poorly understood. As noted by Kennett (2005:129), “compared with sites dating to the Late Holocene, most sites dating to the Middle Holocene have a low density of artifacts and are sometimes difficult to place chronologically without radiocarbon dating.” Of the sites identified on Santa Cruz Island, few have been adequately tested, and these are mainly located on the west (see Glassow 1997) and east ends of the island (see Perry 2003). Between 2006 and 2008, I assisted Jennifer Perry in the small-scale testing of four middle Holocene sites located in the Central Valley (see Perry and Delaney-Rivera 2011), and have undertaken the analysis of macrobotanical remains from these samples (Hoppa 2010). Through a collaborative grant with Professor Amber VanDerwarker (UCSB), I have recently acquired funds and have set up a microbotany lab in the Department of Anthropology, in order to recover both starch grains and phytoliths from artifacts and soil samples. The proposed recovery of archaeobotanical samples will build on my previous research and specifically target microbotanical remains for analysis in this new lab. These preliminary results will help me in designing my dissertation research, for which I plan to seek extramural funding. Additionally, the collection of modern native plants on Santa Cruz Island will be an integral part of this project, as the samples acquired will be used to generate starch and phytolith slides for a comparative collection. Moreover, I intend to publish the images from our comparative collection as a means to contribute to the growing body of online pictorial guides in the field. Methods Fieldwork will include excavation at two sites located in the Central Valley, and collection of plant samples from within the Santa Cruz Island Reserve. This work will take place during three trips of five days each, with a crew of four people, during the spring and summer of 2012. Plants collected for the comparative collection will be processed for preparation of starch and phytolith slides upon immediate return from the field. Laboratory analysis will require the sorting of recovered archaeological materials (both floral and faunal), and will take place over the fall, winter and spring of 2012-2013. The final report for this project will be completed by fall of 2013. Excavations. Archaeological samples will be obtained from CA-SCRI-183, and -163. CA-SCRI-183 is located in the Central Valley near a modern oak stand. Dr. Jennifer Perry and I tested this site as part of our 2007 project, and obtained radiocarbon dates of 4600-4230 and 4850-4510 years ago, placing it well within the Middle Holocene. CA-SCRI-163 is also located in the Central Valley and was described by Rogers (1929) as an “interior village site.” Located within the main ranch complex, it has suffered some surface damage; however, ground stone artifacts often have been found there after storms. The possibility of recovering ground stone artifacts makes this site particularly appealing, as these artifacts are ideal for recovering starch grains and phytoliths. Testing will consist of 1 x 0.5 m pits excavated from surface to the base of the archaeological deposits, in arbitrary 10 cm increments (or in natural strata, should those be visible). Processing Archaeological Material. From each excavation pit, 50 grams of soil will be removed for starch and phytolith processing. Remaining material will be processed through a Flote-Tech Machine-assisted Flotation Device in Anthropology’s Collections Processing Laboratory. This device prevents contamination between samples and has high recovery rates: 96% for seeds greater than 2 mm and 86% for seeds greater than 0.5 mm but less than 1 mm (Hunter and Gassner 1998:149). Light fraction material will be recovered in a 0.5 mm flotation mesh, and heavy fraction material will be recovered in a 1 mm mesh. Though the heavy and light material will be sorted separately, all material will be separated through geological sieves (2.0 mm, 1.4 mm, and the remainder) and sorted under a stereoscopic microscope (40x magnification). All carbonized plant material will be sorted to the lowest taxonomic level possible, using both published seed identification guides (e.g., Martin and Barkley 1961) and the comparative collection at the University of California, Santa Barbara. Wood charcoal will be weighed but not counted, while all seeds will be weighed and counted. Starch and Phytolith Analysis. Following Chandler-Ezell and Pearsall’s (2003) “piggyback” method, starch and phytolith samples will be removed from the soil samples and ground stone artifacts, using lithium metatungstate as a heavy liquid. This process allows for the extraction of both starch and phytoliths from a single sample by first using a heavy liquid which is denser than starch but not phytoliths, so that the starch may be decanted off. Increasing the density of the heavy liquid will then allow for the decanting of the phytoliths. (Hydrochloric and nitric acid are used to remove organics from the phytolith sample; thus it is crucial to remove the starch grains before this step). The extracted starch grains and phytoliths will be identified to the lowest possible taxonomic level using a biological microscope (100-400x) and comparative collections at the University of California, Santa Barbara. Expanding the Comparative Collection. Plants collected for the comparative collection will require small samples from as many parts of the plant as possible (i.e., leaves versus roots), to be processed for preparation of starch and phytolith slides. Starch slides will be made from fresh samples of roots, tubers, etc. Phytolith slides will be made by incinerating plant samples and then removing organics with hydrochloric and nitric acid (just as with archaeological soil samples). Significance While we know a great deal about historical plant use among the native Chumash (largely derived from the ethnographic field notes of John P. Harrington), it is problematic simply to extend contact-period plant use back into the past uncritically. Within the Santa Barbara Channel region, the role of plants has been largely inferred from ethnographic studies (see Timbrook 2007 for a thorough discussion of Chumash ethnobotany), artifact association (e.g., the presence of mortars and pestles used to infer acorn processing), or limited macrobotanical analyses (see Martin and Popper 2001). Indeed, there has been startlingly little research conducted on archaeological plant remains. Thus, most reconstructions of plant- based diet are based on indirect evidence of plants. As the first study to combine macro- and micro- botanical analysis of plants on Santa Cruz Island, this project would not only provide direct evidence, but would potentially recover a much broader range of taxa than a project limited to macrobotanical analysis. The archaeological data recovered will contribute to ongoing research of middle Holocene settlement and subsistence, particularly the use of terrestrial resources; while also generating comparative data for future microbotanical studies within the Santa Barbara Channel region. In particular, this project will provide the basis for designing my dissertation project, and the resulting information will be necessary for seeking extramural funding (e.g., NSF dissertation improvement grant).

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Reconstructing Prehistoric Plant Use on Santa Cruz Island

graduate_student - University of California, Santa Barbara

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Group of 2 Graduate Student Aug 19 - 21, 2012 (3 days)

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