The grain fabric of a laboratory antidune composed of coarse‐ to medium‐grained sand shows a high‐angle upcurrent imbrication both on the upstream and downstream sides. Such a grain fabric differs from a normal dune or a megaripple, where grain alignment displays an upcurrent imbrication relative to the depositional slope in the foreset lamina and/or near parallelism with the slope surface in the toe‐set lamina. Recognition of antidunes in ancient rocks is difficult, but detailed examination of grain fabric of cross‐stratification makes it possible to distinguish antidunes or ‘backset’ bedding from normal dunes or megaripples.
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Yagishita et al. (1989) studied this question.