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Show 97 college of social & behavioral science Range Creek Canyon (RCC), UT was occupied by the Fremont between 800 A.D. and 1200 A.D. Data were collected from a sediment core extracted in summer of 2011 from a site identified as the North Gate bog (NGB). The purpose of collecting data from this core was to identify environmental drivers which could have led to the abandonment of the site by the Fremont. Two cores were extracted from NGB using a Livingstone corer and the cores were wrapped in plastic wrap and aluminum foil on site. These cores were then transported to the RED lab on the U of U campus where they were relocated to cold storage. When tested, the magnetic susceptibility (MS) results of both cores showed the core titled NGB11B was more favorable core for analysis due to the greater variability in the magnetic readings. The NGB11B core was divided up into 1 cm contiguous sections and samples for loss on ignition (LOI) were then collected. A 1 cc subsample was taken every 4 cm and each of the wet samples were weighed to get an initial measurement. The samples were then subject to three separate burns of 100 °C for 24 hours, 550 °C for 2 hours, and 900 °C for 2 hours to determine the percentage of water, organic and carbonate (CaCO3) content, respectively (Dean, 1974). Charcoal data were also collected. A 5 cc subsample was taken from every 1 cm sample to quantify the charcoal particles of size >250 microns and 125-250 microns. These sizes are counted because during a fire event particle sizes >100 microns are not transported far before being deposited and this will provide a local (watershed scale) fire history (Whitlock and Larsen, 2001). The data collected have thus far supported the current findings of what the paleoenvironment was at the time of the Fremont occupation (Morris, 2010). The increase in MS correlated with the decrease in percent of organics which indicate organics were likely used to fuel fire events and the expected ero-sion following a fire explains the increase in nonorganic material which would be washed down slope and deposited in the bog. The charcoal data from the RCCNGB core was not dated so it was correlated with the charcoal data collected from Morris (2010) to get an estimated date range. As previously mentioned, the Fremont abandonment happened roughly 1200 A.D. (Morris, 2010) and the charcoal data are assumed to be from periods of fire events at the end and after Fremont occupation. While the Fremont occupied the area, they would have used fire as a tool for agriculture or prevention of larger fires during the dry season. It is assumed following abandonment, fuels would have built up leading to a large fire event such as is seen around 1600 A.D. on both charcoal counts. The large fire event appears to have been a catalyst for new vegetation as indicated by a significant increase in organics. References Dean, W. E. (1974). Determination of carbonate and organic matter in calcareous sediments by loss on ignition comparison to other methods. Journal of Sedimentary Petrology, 44, 242-248. Morris, S. R. (2010). After the Fremont: Fire and vegetation history of prehistoric abandonment and historic occupation of Range Creek Canyon, Utah, 1-55. Whitlock, C. & Larsen, C. (2001). Charcoal as a fire proxy. In J. P. Smol, H. J. B. Birks & W. M. Last (eds.), Tracking environmental change using lake sediments. Volume 3: Terrestrial, Algal, and Siliceous Indicators (pp. 75-97). Dordrecht, The Netherlands: Kluwer Academic Publishers. A STUDY OF PALEOENVIRONMENTS IN RANGE CREEK CANYON, UT Becky Eden, (Andrea Brunelle) Department of Geography University of Utah UNDERGRADUATE RESEARCH ABSTRACTS Becky Eden Andrea Brunelle |
