1. Recent developments in quantitative interpretation of fluvial dune deposits: an application to the Quaternary Loire River, France Suzanne F. Leclair Tulane University, New Orleans, LA http://www.tulane.edu/~eens/geol/faculty/leclair.html Eric C. Straffin 1 and Michael D. Blum 2 1. Edinboro University of Pennsylvania 2. Louisiana State University, Baton Rouge, LA

2. Context of this study Fluvial response to allogenic forcing over the last glacial cycle: large rivers of southern France Objective of this study Using characteristics of preserved cross-sets to reconstruct the paleohydraulic response of the Loire River to changes in flood regime during the late Quaternary. (using methods described in Leclair and Blom, IAS spec. Publ. 35, in press; Leclair & Bridge, JSR, 2001)

3. Results from 2 downstream sites near Orleans Results from 2 downstream sites near Orleans Observed Mean Cross-set Thickness = 0.12 m Estimated Mean Dune Height  0.35 m Estimated Mean Flow Depth  1m Lower unit: Obs. Mean Cross-Set Tk= 0.1 m Est. Mean Dune Height  0.3 m Est. Mean Flow Depth  0.8 m Holocene Late Pleistocene (Near-bank situation)

4. Late Pleistocene Loire Predicted mean dune height averages 0.5m (0.3 – 0.8m) Predicted mean dune height averages 0.5m (0.3 – 0.8m) Predicted flow depth ranges from 1 - 3 m Predicted flow depth ranges from 1 - 3 m Modern Loire channel Conclusion: Modern floods are typically 2 times as deep as late Pleistocene floods Flow depth  2 - 6 m Preliminary results from 7 downstream sites near Orleans

5. Questions for future research What are the criteria to distinguish deposits from ‘distinct’ events within a channel? What is the preservation potential for deposits from a single event? What is the effect of partial record of event deposit on analysis? I plan to address these issues by doing research on modern rivers, laboratory experiments, and modeling (computer simulation) If you are interested, please contact me at leclair@tulane.edu leclair@tulane.edu