Loess, eolian processes, stream valleys, drainage development, joint patterns
Analysis of stream valley alignment reveals that first-order valleys, which are formed entirely within Wisconsinan loess, show a strongly preferred orientation of N40-50 degrees W, within an otherwise random distribution. This alignment is present in NW, W Central, and Central Iowa. It is not apparent in S Iowa. In NE and E Iowa wind-aligned features change to a N60-70 degree W orientation. This is interpreted as wind-alignment of the low-order valleys within the loess, created by prevailing NW winds during or shortly after loess deposition. Higher order streams are controlled by the till landscape beneath the loess. The four directions of preferred orientation in these higher order valleys are coincident with till joints.
Proceedings of the Iowa Academy of Science
© Copyright 1979 by the Iowa Academy of Science, Inc.
Hallberg, George R.
"Wind-aligned Drainage in Loess in Iowa,"
Proceedings of the Iowa Academy of Science: Vol. 86:
, Article 4.
Available at: http://scholarworks.uni.edu/pias/vol86/iss1/4