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Pacific Coastal & Marine Science Center

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

Cross-Bedding, Bedforms, and Paleocurrents

Photographs

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

FIG. 23.  Structure inferred to have formed by a dune that fluctuated in asymmetry and migration speed; eolian deposits in the Cedar Mesa Sandstone Member (Permian) of the Cutler Formation, southeast Utah.

RECOGNITION: Cyclic foresets, such as those in this example, clearly indicate cyclic depositional processes.  The bedding in this set of cyclic foresets has a characteristic that suggests that the cyclicity was caused by fluctuating flow: wedges of sediment deposited along the lee slope (light-colored bottomset and foreset beds). Deposition of these basal wedges suggests that the cyclicity was produced by fluctuations in asymmetry and migration speed, as simulated in Figure 22A.

 

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