Great Plains
Revisiting the Dust Bowl: Dust sources during the "dirty thirties"
This research, in collaboration with Steve Forman and graduate students Kasey Bolles and Taylor Weeden at Baylor University, questioned the 80-year paradigm that drought plus poor farming practices were the sole source of dust during the 1930s Dust Bowl Drought. Our results revealed that reactivation of vegetated sand dunes and sand sheets may have contributed up to 60% of the dust in the Southern High Plains. We have moved our studies to the Northern Great Plains which were also battered by drought and dust storms. The photos below showcase a dust storm approaching Vermillion, SD in May of 2022, compared to a dust storm in Gregory, SD in 1934 below, and a wind eroded sand sheet in Kansas.
Publications
Bolles, K., Sweeney, M., Forman, S., 2019, Meteorological catalysts of dust events and particle source dynamics of affected soils during the 1930s Dust Bowl drought, Southern High Plains, USA. Anthropocene, v. 27, p. 1-23, doi:10.1016/j.ancene.2019.100216.
Bolles, K., Forman, S.L., Sweeney, M.R., 2017, Eolian processes and heterogeneous dust emissivity during the 1930s Dust Bowl Drought and implications for projected 21st century megadroughts. The Holocene, v. 27(10), p. 1578-1588. doi:10.117/0959683617702235
Erosion of loess as a source of dust
In collaboration with Joe Mason at the University of Wisconsin, we used the PI-SWERL to measure the potential for loess to emit dust. Loess landscapes, due to their vegetative cover, are dust traps, facilitating loess aggradation. During drought and reduction in vegetation density, loess could erode and become a source of dust. Coarser, sandy loess is most susceptible to wind erosion. A surprising find was that dust can be emitted from loess by direct aerodynamic entrainment in the absence of saltation. This research supports the hypothesis that large, wind-aligned scarps formed in thick Peoria Loess in Nebraska were likely eroded by the wind.
Undergraduate student involved: Zac Irvine (pictured), 2010-2011
Publication:
Sweeney, M. R., Mason, J.A., 2013, Mechanisms of dust emission from Pleistocene loess deposits, Nebraska, USA. Journal of Geophysical Research – Earth Surface, 118, doi:10.1002/jgrf.20101.
South Dakota Loess
Student research has revealed that the source of loess in South Dakota is complex but the loess is in part correlative to the late glacial Peoria Loess of the Great Plains. More research must be completed to pinpoint potential sources.
Students involved: Rachel Spitzer (Jensen), 2018-2019; Kathryn Rathbun, 2009-10; Wendy Stiernagle (pictured), 2007
Student Abstract:
Rathbun, K., and Sweeney, M., 2010, Source and paleoclimatic significance of loess in southeast South Dakota. Geological Society of America Abstracts with Programs, v. 42, no. 3, p. 41. Won best undergraduate student poster presentation, Rocky Mt. GSA
