Freshwater megaflood sedimentation: What can we learn about generic processes?

Despite considerable variation in megaflood sedimentary successions, commonalities occur which are indicative of similar processes of deposition from high energy floods at geographically different locations. The changes in style of deposition throughout a succession provide clues as to the nature of the flood flows and this information could be used to improve estimates of flood hydrograph behaviour. However, hypotheses linking deposit characteristics to flow dynamics are currently ill-conditioned and often poorly tested. The majority of published studies describe the coarser-scale stratigraphy, with only passing reference to the fine-scale structure of individual beds. Closer attention to lamination styles, particle orientation and syn-depositional deformation structures, for example, should provide information on the flow mechanics at the time of bed deposition. Thus, better consideration of the sedimentology of megaflood deposit beds will lead to better understanding of the controlling hydraulics and should result in better models of flood deposition.