CONTROLS OF WOODY DEBRIS ORIENTATION IN MEANDERING FLUVIAL SYSTEMS: HENRYS FORK OF THE SNAKE RIVER, MADISON COUNTY, IDAHO

Woody debris (WD) located along the Henrys Fork of the Snake River, Madison County, Idaho was examined by measuring debris orientations in relation to flow direction to test the hypothesis that fossilized WD records paleocurrent attitudes in fluvial deposits. This hypothesis has recently been challenged by a number of researchers with inconsistent results, ranging from parallel to perpendicular preferred orientations or no correlation at all, depending upon the methods used, nature of the WD, and characteristics of the stream examined. Our study takes a new approach by accounting for debris shape and complexity and position of the debris within the channel profile. These analyses have identified factors that appear to control WD orientation, possibly explain some of the variability reported in other studies, and provide a potential means for interpreting flow direction based on WD shape as preserved in meandering fluvial systems.