Graduation Year

1983

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Department

Geology

Degree Granting Department

Geology

Major Professor

Richard A. Davis Jr.

Committee Member

Mark T. Stewart

Committee Member

Sam B. Upchurch

Abstract

Bunces Key, a narrow, linear, barrier island on the west-central coast of Florida, was founded in 1961. Its growth and development since that time is well documented by aerial photography. Cores taken from the Key and surrounding areas reveal a stratigraphic succession of facies reflecting rapid vertical aggradation. Sedimentation began on a gently sloping platform through the landward migration of large scale bedforms (sand waves) during fair weather periods. Migration of these bedforms ceased when emergence and lack of continued overwash precluded further movement. Vertical accretion to supratidal levels resulted from the continued onshore transport of sediment and subsequent welding to the previously formed bars. Stratigraphically, the barrier exhibits a "layer-cake" type of stratigraphy, with nearshore sediments overlain by foreshore, backbeach, and dune deposits. The backbarrier generally exhibits muddy lagoon sediments intercalated with washover and channel margin sediments.

Fining upward washover sequences reflect the unstable nature of the island. Low pressure systems commonly cause overtopping of the barrier, with the subsequent formation of tidal inlets and washover fans. Aerial photographs document the formation of an initial barrier that was breached twice prior to 1973. A second barrier formed in late 1973 just seaward of the initial island and subsequently grew through littoral drift to a length of 1.8 km. A narrow inlet (30m) formed through the northern end of the island in 1982.

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