Tuesday, July 12, 2016

Highlights—In the Backwater of Tidal–Fluvial Interactions

As noted by Elvis and Ecclesiates, rivers flow surely to the sea. Yet, exactly what happens to rivers just before they get there is not well constrained, but has been interpreted to control avulsion nodes, and therefore, distributary channel patterns. To test scenarios of backwater hydraulics (especially water-surface drawdown) on sedimentology and morphology of lower-delta plain distributary channels, Columbera et al. describe field observations of the Cretaceous Neslen Formation (Campanian, Mesaverde Group) of the Book Cliffs in Utah. The results reveal ribbon sand bodies with architecture, lithofacies, and bounding surfaces and strata that are broadly consistent with patterns that would be expected in the region of rivers where the streambed drops below sea level.  Nonetheless, the authors conclude by noting a need for additional research on these processes in the rock record, and the appropriate revision of sequence stratigraphic models.

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