Thursday, March 14, 2013

Highlights—Tropical Storms Shape Deltas

Deltas represent generally lobate sediment accumulations formed by sediment from rivers that empty into standing bodies of water.  In these settings, storms and tropical cyclones can represent events of high energy.  To assess the role storms in formation of deltas, Garrison et al. compare the timing of the deposition of stratigraphic units, constrained by 137Cs geochronology and historical aerial photographs, and the historical record of storms in the Holocene Gum Hollow Delta (Nueces Bay, Texas Gulf of Mexico).  Results indicate that broadly coarsening- then fining-upward bedsets, interpreted to represent waxing- and waning-flow phases interpreted to represent hyperpycnal deposits.  Comparison with historical records and aerial photos reveal that these deposits are associated with tropical cyclone landfalls throughout the 80-year historical record.  These results suggest that such deposits can be used as a tool to investigate climate records in sedimentary successions in small estuarine and lagoonal deltas.

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