Tag: Daniel Gavin

A 10,500 Year Paleoecological Record of the Interior Rainforest of Eastern British Columbia

Presenter: Ariana White

Mentor: Daniel Gavin

PM Session Oral Presentation

Panel Name: A1 Evolutionary Trajectories

Location: Alsea Room

Time: 11:00am – 12:00pm

Although there have been multiple investigations into the coast range and island ecosystems of British Columbia, the climate and forest history of the interior is less well studied. The interior of British Columbia houses one of the largest temperate rain forests in North America due to its location along the wet westernmost portion of the Rocky Mountains. In our investigation, we posit that this biome has shifted in location in accordance with changes to the climate system through the centuries. Morkill Lake, British Columbia, is located at the northern terminus of the inland wet belt zone in the Fraser River valley. The ecotone in which the lake is located represents the very edge of this unusual biome at the place where the rainforest gives way to drier and colder boreal forest. We present a pollen record from Morkill Lake which extends back 10,500 years BCE and illustrates the biological dynamism and basic climatological characteristics of this area through millennia of transition.

Changes in Lacustrine Sediment Lithology from ca. 45,000 to 22,000 Years Ago Reveal Glacial Environments Near Triangle Lake, OR

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.