Geography Faculty Works

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  • ItemOpen Access
    Subfossil chironomid calibration data set from the Intermountain West
    (Cambridge University Press, 2014) Baig, Jamila; Gavin, Daniel G.; Porinchu, David
    Subfossil chironomid (non-biting midges) head capsules are ubiquitous and well preserved in lake sediment. Because many of these taxa are stenothermal with respect to summer air temperature (when larvae develop), species assemblages preserved in lake sediment records may be used to reconstruct air temperature. However, such reconstructions requires a calibration data set derived from surface sediments from a network of lakes. Haskett and Porinchu (2014) developed a 91-lake database of fossil chironomids which has not yet been publically archived. As part of a study of reconstructing air temperature at Gold Lake (Oregon) over the Holocene, Baig et al. (in press) utilized this dataset. In using the dataset, site locations and elevations were corrected at some sites. These corrections were used to develop updated estimates of mean July air temperature (MJAT) at each lake using downscale-adjusted (using local lapse rates) estimates from PRISM climate grids using the ClimateWNA software (Wang et al. 2016). Haskett, D. R., and D. F. Porinchu. 2014. A quantitative midge-based reconstruction of mean July air temperature from a high-elevation site in central Colorado, USA, for MIS 6 and 5. Quaternary Research 82:580–591. Baig, J., D. G. Gavin, I. R. Walker, and D. F. Porinchu. (n.d.). Chironomid-inferred postglacial temperature reconstruction from Gold Lake, Oregon, USA. Quaternary Research in press. PRISM Climate Group., 2020. PRISM Climate Group. Oregon State University. http://www.prism.oregonstate.edu/ Wang, T., A. Hamann, D. Spittlehouse, and C. Carroll. 2016. Locally downscaled and spatially customizable climate data for historical and future periods for North America. PLOS ONE 11:e0156720.
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    ItemOpen Access
    Data, images, and R programming language code for age-depth modeling a lake sediment record
    (2024-10-14) Gavin, Daniel G.
    Langlois Lake in western Washington contains evidence of overbank flows (floods) onto an alluvial fan surface from the adjacent Tolt River. A six-meter sediment core from the lake, and a freeze core of the surface sediments, reveals the timing of these overbank flows as distinct silt units in the sediment. Radiocarbon dates and Pb-210 measurements provide a basis for aging these layers. However, due to the very different rates of sedimentation of the silt vs organic segments of the core, there is a complicated relationship between depth in the sediment and age of the sediment. Typical methods have simply removed the "slumps" of the rapidly-deposited material; this is a subjective step and difficult to apply for long cores with many such events. The method used here, originally used in two papers (Colombaroli and Gavin 2010, Colombaroli et al. 2018), uses an estimate of the fluvial silt component of sediment (from color or density) as a proxy for sedimentation rate. The R code (R programming language) and data sets here accompany an application of this method to Langlois Lake. We also provide image files of the sediment record which this method depends. Colombaroli, D., & Gavin, D. G. (2010). Highly episodic fire and erosion regime over the past 2,000 y in the Siskiyou Mountains, Oregon. Proceedings of the National Academy of Sciences of the USA, 107(44), 18909–18914. https://doi.org/10.1073/pnas.1007692107 Colombaroli, D., Gavin, D. G., Morey, A. E., & Thorndycraft, V. R. (2018). High resolution lake sediment record reveals self-organized criticality in erosion processes regulated by internal feedbacks. Earth Surface Processes and Landforms, 43(10), 2181–2192. https://doi.org/10.1002/esp.4383)