The northern slopes of the Uinta Mountains, Utah were previously glaciated and contain many landslides. The Tokewanna Landslide is very large and lacks Quaternary faults. Presumably, increased moisture was the failure trigger. A Quaternary climate record from a cored fen, developed in a small basin between hummocks, was reconstructed using sediment pyrolysis, biomass balance, and magnetic susceptibility. Pyrolysis is used to define Hydrogen Indices that are used to delineate wetter and drier conditions based on the kerogen type - Type III being drier, and Type II wetter. The data were matched to a time/depth curve and compared to other Uinta Mountains climate studies. Pyrolysis, biomass balance, and magnetic susceptibility results indicate drier to wetter conditions from ~11,027 to ~8,800 cal yr BP. This was followed by an increase in precipitation, peaking ~8,060 cal yr BP, and then decreasing. Drying conditions ensued after ~4,800 cal yr BP, and from ~1,700 cal yr BP to modern. Regional studies suggest mid-Holocene Epoch warming; some also indicate increased precipitation during those periods. A study at nearby Little Lyman Lake (Tingstad et al., 2011) displays a plankton percent record similar to the wetness record of the study fen. The fen core record does not indicate wet conditions at its base as expected. The record begins ~11,000 cal yr BP and likely represents an incomplete history of this Holocene fen, as the base of the wetland deposits was not reached.
College and Department
Physical and Mathematical Sciences; Geological Sciences
BYU ScholarsArchive Citation
Hillam, Samuel Abraham, "A Quaternary climate record from a Uinta Mountains, USA, fen core with emphasis on sediment pyrolysis" (2017). All Theses and Dissertations. 6676.
Uinta Mountains, modern sediments, pyrolysis, Holocene, wetland, fen, paleoclimate