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2017
Tuesday, April 11th
9:00 AM

Magnetic Susceptibility of Loess Paleosol Sequences at Clyde: A Proxy for Paleoclimate?

Gabby McGann, Whitman College

Science 159

9:00 AM - 9:15 AM

The Palouse loess is an extensive region of windblown silt that covers up to 50,000 square kilometers of southeastern Washington and parts of Oregon and Idaho. Around the world, the magnetic susceptibility of similar loess paleosol sequences has been successfully used to reconstruct past climate. However, this technique has not been tested in the Palouse area. We measured the magnetic susceptibility of the loess paleosol sequences at the Clyde outcrop and compared it to published records to determine if trends in magnetic susceptibility correspond to local trends in climate conditions. Using SEM and EDS, we analyzed samples from the outcrop to determine whether the magnetic phases were mineralized during soil formation. I share the results of this research in my presentation.

9:15 AM

Magnetic Susceptibility of the Palouse Loess as a Paleoclimate Indicator

Molly Coates, Whitman College

Science 159

9:15 AM - 9:30 AM

Loess is silt-sized, windblown sediment that can form thick deposits such as the Palouse loess north of Walla Walla. The magnetic susceptibility of sediment in these loess deposits has been used to reconstruct past climate for hundreds of thousands of years of history. However, this technique has not been used in the Palouse loess. We measured the magnetic susceptibility of loess from a previously studied outcrop northwest of Walla Walla and compared it to published paleoclimate data. Magnetic susceptibility of the sediments changes consistently and measurably with time. We measured grain size to test the hypothesis that changes in grain size influence magnetic susceptibility. If these variables are correlated, grain size may be a useful proxy for paleoclimate in the Palouse.

9:30 AM

Geochemical Analysis of Columbia River Basin Vineyard Soils

Alex Ihle, Whitman College

Science 159

9:30 AM - 9:45 AM

Soil mineralogy and chemistry are major environmental factors, along with climate and geomorphology, that affect vineyard health, wine production and flavor. My presentation focuses on the mineralogy and chemistry of vineyard soils in the Columbia River Basin. The vineyards in this region are in a unique geologic setting, with iron-rich basaltic bedrock overtopped by silica-rich sediments. The chemistry of local vineyard soils, which are developed within these silica-rich sediments, shows elevated iron levels similar to those in basalt, but the mineralogical data does not show abundant iron-bearing minerals. A better understanding of how soil chemistry and mineralogy are connected will help grape growers better target specific soils for desired properties such as iron content, a key nutrient for plants.