Preservation of cross-sets due to migration of current ripples over aggrading and non-aggrading beds: comparison of experimental data with theory

An experimental study of the preservation of cross-sets during the migration of current ripples under aggrading and non-aggrading conditions was conducted in order to test the modi®ed Paola±Borgman theory for distribution of cross-set thickness as a function of distribution of bed-wave height. In a series of ̄ume experiments, the geometry and migration characteristics of the ripples did not vary systematically with aggradation rate and are comparable to other ̄ume and river data. Mean cross-set thickness/mean formative bed-wave height is less than 0á4, and mean cross-set thickness/mean bed-wave height is less than 0á53. In the present experiments, the primary control of cross-set thickness is the variability of ripple height. Aggradation rate accounts for only 1±7% of the total cross-set