Formulations for the wavelength (X) and height (r\) of stable sand ripples in oscillatory flow have been proposed in terms of fundamental flow parameters by, among others, NIELSEN (1981) andGRANT andMADSEN (1982). In both formulations the parameterisation distinguishes between laboratory and field data. More recently, WIBERG and HARRIS (1994) have proposed a common classification for both laboratory and field data, arguing that the main difference between the two cases is that they differ by an order of magnitude in dJD, where d0 is the near-bed wave orbital diameter andD is the grain diameter. In this classification, the ripples are subdivided into three groups: orbital, suborbital and anorbital. The basic scaling of orbital ripples is ond0, and of anorbital ripples is onfl; suborbital ripples represent the transitional region between these two limits.