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Behavior of the James Lobe, South Dakota during Termination I

Heath, Stephanie L

Abstract Details

2019, PhD, University of Cincinnati, Arts and Sciences: Geology.
The Laurentide Ice Sheet was the largest ice sheet of the last glacial period that terminated in an extensive terrestrial margin. This dissertation aims to assess the possible linkages between the behavior of the southern Laurentide margin and sea surface temperature in the adjacent North Atlantic Ocean. Toward this end, a new chronology for the westernmost lobe of the Southern Laurentide is developed and compared to the existing paradigm of southern Laurentide behavior during the last glacial period. Heath et al., (2018) address the question of whether the terrestrial lobes of the southern Laurentide Ice Sheet margin advanced during periods of decreased sea surface temperature in the North Atlantic. This study establishes the pattern of asynchronous behavior between eastern and western sectors of the southern Laurentide margin and identifies a chronologic gap in the western sector. This is the first comprehensive review of the southern Laurentide margin since Denton and Hughes (1981) and Mickelson and Colgan (2003). The results of Heath et al., (2018) also revealed the lack of chronologic data from the Lobe, South Dakota, the westernmost lobe of the southern Laurentide margin. To address this problem, surface exposure age dating is applied to James Lobe deposits within the Pierre Sublobe, a westward-flowing sublobe of the western James Lobe. A new geomorphic map of the Pierre Sublobe is produced to provide geologic context for 10Be surface exposure age dating efforts. Results of this study offer insights into possible problems associated with site selection in this region and yields some insight into the behavior of the James Lobe during Termination I. The history of the main trunk of the James Lobe is expanded upon using radiocarbon ages compiled from South Dakota Geological Survey reports. Three stratigraphic cross sections of the James Lobe are assembled to provide stratigraphic context for these radiocarbon ages Results of this study bear on the timing of maximum extent of the James Lobe, as well as advance and retreat patterns of the lobe during late-glacial time. The James Lobe is compared to the neighboring Des Moines Lobe in Iowa and the existing paradigm of surging and streaming is evaluated. Finally, the behavior of the James and Des Moines Lobes is compared to the rest of the southern Laurentide margin for three time slices to evaluate the asynchronous relationship established in Chapter 2 (Heath et al., 2018). Results of this study bear on differences between extent and timing of the lobes, and the mechanisms that may have controlled southern Laurentide margin position during the last glacial period and termination. This dissertation affords insight into the patterns of advance and retreat of the southern Laurentide Ice Sheet during the last glacial period and Termination. In reconstructing these behaviors and producing a new chronology for the westernmost Laurentide lobe, this work offers new perspective for the mechanisms that controlled southern Laurentide margin position during the Termination.
Thomas Lowell, Ph.D. (Committee Chair)
Aaron Diefendorf, Ph.D. (Committee Member)
Aaron Putnam, PhD (Committee Member)
Dylan Ward, Ph.D. (Committee Member)
129 p.

Recommended Citations

Citations

  • Heath, S. L. (2019). Behavior of the James Lobe, South Dakota during Termination I [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563527630491659

    APA Style (7th edition)

  • Heath, Stephanie. Behavior of the James Lobe, South Dakota during Termination I. 2019. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563527630491659.

    MLA Style (8th edition)

  • Heath, Stephanie. "Behavior of the James Lobe, South Dakota during Termination I." Doctoral dissertation, University of Cincinnati, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563527630491659

    Chicago Manual of Style (17th edition)