Classification of Ripple Marks

Abstract

Although ripple marks are extensively used in paleogeographic and environmental reconstructions, there is no generally accepted classification of them. The few formal classifications that have been proposed and the many informal classifications that have been used commonly recognize two major classes of ripples: current and either wave or oscillation types. Despite the seeming simplicity of this system, confusion has arisen because usage varies considerably. In some cases the same ripple type has been called current, wave-formed, or oscillation ripples by different authors. To resolve this problem we propose a classification that recognizes four major ripple types: wave formed, current formed, interference, and eolian. Three of the groups are aqueous, the fourth eolian. Within each group several varieties are distinguished. The most common varieties are: (wave-formed) oscillation, linear, and wave-dominated combined-flow; (current-formed) cuspate, linguoid, dune, antidune, and current-dominated combined-flow; (interference) tadpole nest, ladderback, cuspate and secondary, and rhomboid; and (eolian) sand ripples. Common names are retained, even where past usage is ambiguous, because they are descriptive and already in general use. Each ripple variety is readily identified by descriptive criteria that are related to mode of formation. Thus the classification is both genetic and descriptive. Accordingly, the ripple types can be identified objectively and also are useful for environmental reconstructions.