Dr. Muhs et Ea. Bettis, Geochemical variations in Peoria Loess of western Iowa indicate paleowindsof midcontinental North America during last glaciation, QUATERN RES, 53(1), 2000, pp. 49-61
Peoria Loess deposited in western Iowa during the last glacial maximum (LGM
) shows distinct geochemical and particle-size variations as a function of
both depth and distance east of the Missouri River. Geochemical and particl
e-size data indicate that Peoria Loess in western Iowa probably had two sou
rces: the Missouri River valley, and a source that lay to the west of the M
issouri River. Both sources indicate that LGM paleowinds in western Iowa ha
d a strong westerly component, similar to interpretations of previous worke
rs, A compilation of loess studies in Iowa and elsewhere indicates that wes
terly winds were dominant during loess transport over much of the midcontin
ent south of the Laurentide ice sheet, which is not in agreement with paleo
winds simulated by atmospheric general circulation models (AGCMs). AGCMs co
nsistently generate a glacial anticyclone with easterly or northeasterly wi
nds over the Laurentide ice sheet and the area to the south of it. Loess de
position in the midcontinent during the LGM may be a function of infrequent
northwesterly winds that were unrelated to the presence of the glacial ant
icyclone. (C) 2000 University of Washington.