Morphology, dynamics and internal stratification of some established foredunes in southeast Australia

Foredunes are shore-parallel dunes formed by aeolian deposition within vegetation. Modern established foredunes are classified into five morphologic stages and the morphologies and processes of each is described. Stage 1 foredunes are well vegetated, symmetric, stable ridges characterised by stoss face and crest deposition. Stage 2 foredunes display minor erosional patches, 75-90% vegetation cover and slight lateral variation in deposition and erosion. Stage 3 foredunes are hummocky, have a 45-75% vegetation cover range, and display various scales of blowouts, concave stoss faces and steeper lee faces. Stage 4 foredunes are characterised by large-scale erosional features such as blowouts, sand sheets and high asymmetry. Stage 5 foredunes comprise poorly vegetated remnant knobs. Each stage is characterised by a set of erosional and depositional processes which produce generally distinctive sets of cross-strata. Sedimentary structures within examples of each foredune stage are examined. Stage 1 and 2 foredunes are dominated by simple, large-scale, convex, continuous strata. Stage 3 and 4 foredunes display increasingly variable sets of cross-strata and a greater degree of planar and trough cross-stratification. Wave-cut scarps, blowout structures and very steep lee slope bedding may be preserved. The internal sedimentary structures presented here, form the basis of a facies model for foredunes.