Topographic and climatic influences on accelerated loess accumulation since the last glacial maximum in the Palouse, Pacific Northwest, USA
Document Type
Article
Publication Date
5-1-2005
Publication Title
Quaternary Research
Keywords
Loess, Mass accumulation rate, Pacific Northwest, Paleoclimate, Topographic trap
Abstract
Topographic and climatic influences have controlled thick loess accumulation at the southern margin of the Palouse loess in northern Oregon. Juniper and Cold Springs Canyons, located on the upwind flank of the Horse Heaven Hills, are oriented perpendicular to prevailing southwesterly winds. These canyons are topographic traps that separate eolian sand on the upwind side from thick accumulations (nearly 8 m) of latest Pleistocene to Holocene L1 loess on the downwind side. Silt- and sand-rich glacial outburst flood sediment in the Umatilla Basin is the source of eolian sand and loess for the region. Sediment from this basin also contributes to loess accumulations across much of the Columbia Plateau to the northeast. Downwind of Cold Springs Canyon, Mt. St. Helens set S and Glacier Peak tephras bracket 4 m of loess, demonstrating that approximately 2500 g m-2 yr-1 of loess accumulated between about 15,400-13,100 cal yr B.P. Mass accumulation rates decreased to approximately 250 g m-2 yr-1 from 13,100 cal yr B.P. to the present. Tephrochronology suggests that the bulk of near-source Palouse loess accumulated in one punctuated interval in the latest Pleistocene characterized by a dry and windy climate. © 2005 University of Washington. All rights reserved.
Volume
63
Issue
3
First Page
261
Last Page
273
ISSN
00335894
DOI
10.1016/j.yqres.2005.02.001
Recommended Citation
Sweeney, Mark R.; Busacca, Alan J.; and Gaylord, David R., "Topographic and climatic influences on accelerated loess accumulation since the last glacial maximum in the Palouse, Pacific Northwest, USA" (2005). Faculty Publications. 96.
https://red.library.usd.edu/sustainability-fp/96