| Description |
Range Creek Canyon in southeastern Utah is the location of hundreds of well-preserved Fremont archeological sites. To determine what living conditions for the Fremont were like during their occupation of Range Creek from 200 AD and 1350 AD, elemental ratios and grain size data were used as proxies for precipitation-induced erosion. These proxies, along with previously analyzed pollen and charcoal data from the spring, were hypothesized to help characterize moisture availability over the last 8,500 years in Billy Slope Bog, a wetland spring within the canyon. Additionally, to create a chronology of climatic events in the canyon, an attempt was made to find tephra from the Mazama eruption of Crater Lake, Oregon, dated 7625 ± 150 cal. yr BP Finally, as a check to the accuracy of the elemental data, the chemostratigraphy of a sediment core from Billy Slope Bog was collected twice, then compared to determine repeatability of the results. The results proved that the elemental data and pollen ratios analyzed had a strong positive relationship, and together reveal a clear picture of how precipitation fluctuated in Range Creek Canyon. Based on the data, the Fremont entered the canyon during a period of high precipitation, and left during drought conditions. However, grain size data did not follow the same trend, and therefore is not an accurate proxy for paleoprecipitation within the canyon. Additionally, based off of spikes in Al, Y, and Ti, a potential location of the Mazama eruption within the core was found. While this data cannot be confirmed without the presence of volcanic glass, the fact that the concentration of yttrium is fifty times higher in this location than anywhere else in the core indicates a sudden depositional event, such as from a volcanic eruption. Finally, the two chemostratigraphies of the sediment core as a whole were positively correlated. The level of positive correlation among individual elements varied, but this difference is probably derived from differences in scanning methodology. Therefore, overall the results indicate that portable XRF data is accurate and repeatable. |
