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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. 37.  Relatively complicated cross-bedding formed by irregular, three-dimensional dunes; eolian deposits in the Temple Cap Sandstone (Jurassic), Zion National Park, Utah.  This photograph shows a real example of the kind of structure simulated in Figure 36.  The sets of cross-beds are as much as several meters thick.

RECOGNITION: The lack of a regular pattern to this cross-bedding suggests that the cross-stratified beds were deposited by bedforms with different shapes or different phase relations between crestlines.  Trough-shaped sets form where adjacent bedform crestlines are locally out of phase (FIG. 34), whereas more tabular sets form where adjacent bedforms are in phase (FIG. 32).  Changes through time may have occurred during deposition of these beds but cannot be demonstrated from the photograph.

 

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