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Pacific Coastal & Marine Science Center

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

Cross-Bedding, Bedforms, and Paleocurrents

Dip plots, static images, and captions

View Animation

Dip plot; see caption below.
Static image of cross-section; see caption below.

FIG. 66.  Structure formed by two-dimensional bedforms migrating down the lee slopes of three-dimensional bedforms.  This depositional situation is identical to the one shown in Figure 25 except that the main bedforms in that example have straight crestlines, whereas the ones shown here have sinuous crestlines. The crests of the superimposed bedforms have the same mean trend as the main bedforms.

RECOGNITION: The crestlines of the superimposed bedforms simulated here do not exactly parallel the crestline of the main bedform.  Consequently, the superimposed bedforms do not migrate directly down the main lee slope at all locations. Instead, at most locations the superimposed bedforms migrate obliquely downslope.  The along-crest component of the locally oblique migration causes the cross-beds to dip in different directions from the underlying bounding surfaces, as shown in the simpler depositional situation where two-dimensional bedforms migrate obliquely down the lee slopes of larger two-dimensional bedforms (Fig. 46A).

ORIGIN: The origin of this structure is essentially the same as that of the structure in Figure 25, except that here the main bedforms have sinuous crestlines.

 

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