Geomorphologists
Project Description: This page is meant to highlight the research and work undertaken by professional geomorphologists
Alison Duvall Phd.
Assistant Professor at the University of Washington.
Department of Earth and Space Sciences
Phd. University of Michigan 2011. M.S. University of California, Santa Barbara, 2003
Bio: Dr. Alison Duvall focuses her research on landscape change and deformation in the perspective of tectonic events and orogenesis. Combining numerical modelling with field observations and laboratory research she analyzes geomorphic evolution of landscapes and complex earth systems.
Recent Publications
Sean R. LaHusen; Alison R. Duvall; Adam M. Booth; David R. Montgomery
Geology (2016) 44 (2): 111–114.
https://doi.org/10.1130/G37267.1
Summery: This is a graduate student oversight paper. This paper outlines a method of regional prediction of landslide events through field observations, LiDAR maps, and absolute dating techniques. Major landslides in the Washington State area were analyzed using LiDAR data and confirmed with in situ observations and measurements. First and secondary mobilization events were determined scarp steepness. Surface roughness was mapped over a region by measured standard deviation of slope and mapped using GIS software. Each landslide event was radiocarbon dated using debris from the toe. Regression of slope roughness as it relates to slide area is correlated, but variation is high. Error analysis shows issues with definitive dating, as well as secondary mobilization categorized as separate events.
Duvall, A. R., and Tucker, G. E. (2015), J. Geophys. Res. Earth Surf., 120, 2016– 2026, doi:10.1002/2015JF003618.
Summery: Strike-slip faults are long features of tectonic lateral movement and indicative of rotational stress. The main geomorphological characteristic of strike-slip faults are sinstral or dextral lateral offsets of topographic features including hills, streams and rivers. In this paper Duvall develops a model of eroding landscapes where parallel basins capture "beheaded" rivers. Factors in the partial differential equation of the model include: Baselevel lowering, lateral tectonic advection rate, incision rate, and erosion/deposition due to soil creep, with independent variables of channel slope, slope length, drainage area, soil flux, and of course strike slip motion. Results show that in areas of slow lateral offset river incision is efficient along lengthening fault offset, whereas mid speed strike slip movement leaves beheaded streams, reduces drainage basins, and allows for new headwaters to form. The fastest strike slip motions revealed stable headwaters and channel capture. This model should create a a stronger basis for lateral offset calculations along the San Andreas where stream capture normally limits the observability of fast margin offset.
Kelly R. MacGregor PhD.
Professor at Macalaster College
PhD. University of California, Santa Cruz
Bio: Dr. Kelly MacGregor is a professor at Macalaster College in Minneapolis, MN USA. She studies geomorphology, glaciology, and through a combination of fieldwork, remote sensing, and mathematics creates models of glacial geomorphology. Kelly has undertaken extensive field work in alpine glaciers across North America. In addition she teaches courses in geomorphology, glaciers and climate, the earth and global change, and hydrology.
Publications:
K.R. MacGregor, R.S. Anderson, S.P. Anderson, E.D. Waddington; Geology ; 28 (11): 1031–1034. doi: https://doi.org/10.1130/0091-7613(2000)28<1031:NSOGLP>2.0.CO;2
Summery: As alpine glaciers are the major factor behind cold and/or high elevation valley erosion systems, MacGregor et al construct a numerical model of an alpine glacier and it's tributaries in longitudinal (long axis) form to look at the simulated effects of overdeepening, tributary contribution, and bed erosion. Due to the lack of data on subglacial hydrology, topography, and geology, certain assumptions on erosion due to hydrologic pressure and quarrying are made. Other well defined parameters such as sliding rates, ice mass pressures, ice deformation, mass balance, elevation, and time (tied to oscillating temperatures according to Oxygen-18 records over 400 ka) are used to construct a model simulation that shows a consistent explanation for hanging valleys of tributary glaciers, and overdeepings at their junctions while the oscillation of glacial advance and retreat will erode trunk-ice subglaical steps and overdeepenings at non tributary junctions.