THE RELATIONSHIP BETWEEN BEDFORM AND LOG ORIENTATION: IS THERE ANY RELIABILITY IN USING WOODY PHYTOCLASTS AS PALEOCURRENT INDICATORS?

Isolated logs preserved in the Älterer Flußsande of the Weißelster basin, Germany, have been examined relative to their subjacent bedform. Paleocurrent analyses have resulted in the recognition of two patterns when the relationship between log orientation and its underlying bedform are evaluated. When the data set is taken collectively, the mean vector of the log orientation is in a subperpendicular relationship to the mean vector of their bedforms. This coarse woody detritus is not oriented preferentially parallel to paleocurrent direction. Additionally, when individual log orientations are compared with their underlying bedforms, logs may be oriented parallel, subperpendicular, or perpendicular to the bedform. There is no statistical preference for any particular orientation in the data set as has been deduced from previously published experimental flume studies. Chi-Square analysis of these flume generated data also indicate that there is no statistical preference for orientation. Comparison is made with an actualistic data set from the Lassa Distributary of the Rajang River delta, Sarawak, Indonesia, where a similar trend is documented. These results caution against the use of woody phytoclasts as independent indicators of paleocurrent trends in fluvial systems.