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Pacific Coastal & Marine Science Center

Bedform Sedimentology Site: “Bedforms and Cross-Bedding in Animation”

Cross-Bedding, Bedforms, and Paleocurrents


Photo of rock or sand showing pertinent structure or structures; see caption below.

FIG. 30. Tidal bundles; modern deposits from the Oosterschelde, The Netherlands, photographed by Joost Terwindt. Set is approximately 1 m thick.

RECOGNITION: As in the computer-generated version of this kind of structure (FIG. 29), ripples migrate up the lee slope, slack water occurs, and then ripples reverse migration direction.  In addition to this geometric evidence of flow reversals, cyclic fluctuations in flow velocity are indicated by the cyclically spaced mud drapes.  Additional details of the origin and interpretation of this structure are given by Terwindt (1981, FIG. 4).  


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