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Erosional and depositional characteristics of regional overwash deposits caused by multiple hurricanes
Author(s) -
WANG PING,
HORWITZ MARK H.
Publication year - 2007
Publication title -
sedimentology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.494
H-Index - 108
eISSN - 1365-3091
pISSN - 0037-0746
DOI - 10.1111/j.1365-3091.2006.00848.x
Subject(s) - geology , overwash , barrier island , sedimentary depositional environment , geomorphology , sedimentary rock , bedding , bay , oceanography , shoal , paleontology , structural basin , shore , horticulture , biology
Regional‐scale washover deposits along the Florida Gulf and Atlantic coasts induced by multiple hurricanes in 2004 and 2005 were studied through coring, trenching, ground‐penetrating radar imaging, aerial photography, and prestorm and poststorm beach‐profile surveys. Erosional and depositional characteristics in different barrier‐island sub‐environments, including dune field, interior wetland and back‐barrier bay were examined. Over the eroded dune fields, the washover deposits are characterized by an extensive horizontal basal erosional surface truncating the old dune deposits and horizontal to slightly landward‐dipping stratification. Over the marshes in the barrier‐island interior, the washover deposits are characterized by steep tabular bedding, with no erosion at the bottom. Overwash into the back‐barrier bay produced the thickest deposits characterized by steep, prograding sigmoidal bedding. No significant erosional feature was observed at the bottom. Washover deposits within the dense interior mangrove swamp demonstrate both normal and reversed graded bedding. The washover deposits caused by hurricanes Frances (2004) and Jeanne (2004) along the southern Florida Atlantic coast barrier islands are substantially different from those along the northern Florida barrier islands caused by Ivan (2004) and Dennis (2005) in terms of regional extension, erosional features and sedimentary structures. These differences are controlled by different overall barrier‐island morphology, vegetation type and density, and sediment properties. The homogeneity of sediment along the northern Florida coast makes distinguishing between washover deposits from Ivan and Dennis difficult. In contrast, along the Atlantic coast barrier islands, the two overwash events, as demonstrated by two phases of graded bedding of the bimodal sediments, are easily distinguishable.