Presenter: Brynn Harrison
Co-Presenters: Daniel Gavin
Faculty Mentor: Daniel Gavin
Presentation Type: Poster 17
Primary Research Area: Science
Major: Geography
The Pacific Northwest has experienced many changes in climate during the most recent glacial period. In order to understand how these changes are documented in the climate record, changes in sediment characteristics were examined in a 60-meter sediment core from a location near Triangle Lake, Oregon. This study focused on using loss- on-ignition to measure organic content, carbon and nitrogen percentages, texture and color analysis, and carbon and nitrogen isotope analysis. Based on the changes in sediment characteristics, the record could be broken down into two sections. The first section of the core, spanning 48,500 to 37,200 cal. yr BP (calibrated years before present), mainly consisted of clays with few visible erosional events (noted by sand layers) spread throughout the section. These sediments were compared with pollen-derived climate descriptions (described by Laurie D. Grigg and Cathy Whitlock) and were found to be consistent with a wet climate that fluctuated between cool and warm temperatures. The second section of the core, spanning 36.9 to 23.4 cal. yr BP, had abundant sand layers. This is consistent with rapid erosion and higher sedimentation rates, and corresponds to a cold and wet climate. Overall, the sediment characteristics correspond well to the pollen-inferred vegetation and provide additional inferences on the erosion as well as terrestrial and aquatic productivity during the period preceding glaciation.