Abstract
Six arbitrary stages of bone weathering were identified in 1978 (Behrensmeyer 1978), using data gathered from animal bones located in surface depositional contexts in the Amboseli Basin of Africa. Since 1978, these six bone weathering stages have been used as a guideline for determining the age of bones according to their weathering stage. Although the weathering stages have been broadly applied across the globe, they have not been verified in all possible geographic locations, i.e., the Sierra Nevada foothills of Northern California. This thesis research studied the effects and rate of bone weathering on domestic pig bones over a period of 133 days to determine the speed of bone weathering in the cool Mediterranean climate of Auburn, California in the Sierra Nevada foothills, and whether or not the rate fit into Behrensmeyer's (1978) six weathering stages. One set of domestic pig bones was placed in an enclosure exposed to full sunlight, and an identical set of bones was placed into an enclosure shaded by an oak tree. The exposure period was from the summer month of July to the winter month of December 2012. Twenty-two sets of domestic pig (Sus scrofa) bones were used for this study. Two identical sets of bones were placed within two reinforced chicken wire enclosures: one shade enclosure, and one sun enclosure. Each enclosure had eleven stations, each station with a set of domestic pig bones consisting of a femur, a rib, and a vertebra. Data was collected over a period of 133 days. Data collected throughout the study period included the ongoing condition of the bones and daily weather patterns, including ambient temperature, UV index, rain, cloud cover, and wind. After 133 days, the bones in this study were still in the condition of Weathering Stage 0, as defined by Behrensmeyer (1978). The bones were in a state of dryness, but no cracks were present on the bone surfaces. This result is consistent with the timeframe of the original weathering stages. The conclusion is that in the cool Mediterranean climate of the Northern California foothills, the early bone weathering stages defined by Behrensmeyer (1978) are valid. To achieve Weathering Stage 1 it may be necessary for a longer study period, possibly up to or at least one year.