Bedform climbing in theory and nature.

Where bedforms migrate during deposition, they move upward (climb) with respect to the generalized sediment surface. Sediment deposited on each lee slope and not eroded during the passage of a following trough is left behind as a cross-stratified bed. Where sediment is transported solely by downcurrent migration of two-dimensional bedforms the thickness of cross-stratified beds is equal to the decrease in bedform cross-sectional area divided by the migration distance over which that size decrease occurs; where bedforms migrate more than one spacing while depositing cross-strata, bed thickness is only a fraction of bedform height. Equations that describe this depositional process are used to explain observations on actual dunes and to predict dune sizes for ancient sandstones. -from Authors