The Role of Shell Material in the Natural Sand Replenishment Cycle of the Beach and Nearshore Area between Lake Worth Inlet and the Miami Ship Channel

Rusnak, Gene A.; Stockman, Kenneth W.; Hofmann, Hermann A.

doi:10.21236/ad0715986

Cited by 4 publications

(4 citation statements)

References 12 publications

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“…Most physical reduction occurs in the shallow marine environment where wave and current activity are high. Tumbling barrel abrasion experiments similar to those of Chave (1960Chave ( , 1964 and Rusnak et al (1966) were carried out as part of this study in order to observe abrasion products. Mollusc shells were used and the size of the particle produced was measured by hydrometer analysis.…”

Section: Othersmentioning

confidence: 99%

Origin and Distribution of Calcareous Fines on the Carolina Continental Shelf

Molnia

Pilkey

1972

Sedimentology

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The fine carbonate fraction (less than 63 μ in diameter) in 175 sediment samples collected from the Carolina continental margin has been studied. This fraction, generally under 5% of the total sample, averages 43% CaCO3. By comparison, the CaCO3 fraction of the total samples averages only 25%. On the inner shelf, the percentage CaCO3 in the fine fraction is twenty or more times greater than the percentage CaCO3 in the total sample. With increased distance offshore, the percentages of CaCO3 in the fine fraction and the total sample approach equality. Beyond the shelf break the percentage of CaCO3 in the total sample is greater than that in the fines. The CaCO3 faunal components are primarily foraminifera, fragments of foraminifera, mollusc‐barnacle fragments and echinoid material. Minor constituents include alcyonarian and tunicate spi‐cules, Halimeda and other calcified green algae. Many grains are bored and show solution effects. The coarse carbonate fraction shows distinct regional faunal assemblages, but the fines are essentially uniformly distributed. Two exceptions are a zone of mollusc fragments around Cape Hatteras and a foraminifera zone on a portion of the outer shelf. The average carbonate mineral assemblage consists of 44% low‐Mg calcite, 38% aragonite and 18% high‐Mg calcite. The principal modes of origin of calcareous fines on the Carolina continental margin are probably biological and physical destruction of coarser particles and primary formation in fine size fraction (as in the case of some foraminifera).

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Section: Othersmentioning

confidence: 99%

Origin and Distribution of Calcareous Fines on the Carolina Continental Shelf

Molnia

Pilkey

1972

Sedimentology

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“…Locally, the presence of shell material in the littoral zone has been related to nearby exposures of coquina along the shore or nearshore bottom (Fineran, 1938); (Martens, 1931). Rusnak (et al, 1966) concluded that old shell material derived from coquina exposures may represent 20 to 60 percent of the carbonate material in east Florida beach sands.…”

Section: Countymentioning

confidence: 99%

“…Loss of beach material in the Miami area could 'then only be due to nearshore longshore movement, or solution of shell material. Rusnak (1966) concluded that loss by abrasion is insj.gnificant .…”

Section: Sediment Distribution and Originmentioning

confidence: 99%

Geomorphology and sediments of the nearshore continental shelf : Miami to Palm Beach, Florida / by David B. Duane, Edward P. Meisburger.

Duane¹,

Meisburger²

1969

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“…The beach material at all three sites is medium to coarse, shelly sand. Rusnak, Stockman, and Hoffman (1966) reported a variable but systematic increase in shell content from Jacksonville south to Miami, with a high of 89 percent near Boca Raton Inlet. They attributed 40 to 50 percent of the shell material to erosion of the Anastasia Formation and the remainder to newly formed shells.…”

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confidence: 99%

Littoral environment observations and beach changes along the southeast Florida coast / by Allan E. DeWall.

DeWall¹

1977

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Beach changes Boca Raton, Florida Erosion side // necessary and Identity by block number) Hollywood, Florida Jupiter, Florida Littoral environment observations Offshore protection Wave climate Waves 20. ABSTRACT fConrlnue on reverse aide II necessary and Identify by block number)Daily and weekly surveys and observations of the beach and nearshore were made at Jupiter, Boca Raton, and Hollywood, Florida, for 4% years between 1969 and1973. During this relatively stormfree period, mean annual breaker height varied from a high of 0.9 meter at Jupiter, the northernmost site, to 0.5 meter at Hollywood, the southernmost site.This decrease in wave energy reaching the shoreline is attributed to the varying protection afforded by the Bahama Banks, 80 kilometers offshore of Hollywood. Wave and longshore (Continued) DD ,7> EDITION OF I NOV 65 IS OBSOLETE UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGE (Whan Data Ente IINPl.A.'^ClTFTFn SECURITY CLASSIFICATION OF THIS PAGE(1Rian Datm Bnland) current directions were observed to change seasonally, with directions from the northeast dominating during October through March and from the southeast during April through September.Potential gross longshore transport rates, estimated from these data, ranged from 1,800,000 cubic meters per year at Jupiter to 1,200,000 cubic meters per year at Boca Raton, to 480,000 cubic meters per year at Hollywood.The magnitude of beach changes, as defined by shoreline position and sand volume on the beach, decreased from north to south and is relatively low compared with typical U. S. east coast beaches. Contributing factors include the sheltering effect of the Bahama Banks, the lack of significant storms, and the underlying coquina limestone which characteristically crops out just below the MSL shoreline, forming a protective reef that effectively retards erosion.Beach changes were seasonal in nature, but were reversed at Boca Raton, where beach width and sand volume were highest during the winter months.Seasonal beach changes were two to three times greater than year-to-year changes. The average unit volume change rate above MSL was -1.8 cubic meters per meter per year at Jupiter, +1.0 cubic meter per meter per year at Boca Raton, and +0.1 cubic meter per meter per year at Hollywood.Corresponding MSL shoreline migration rates were -0.1 meter per year at Jupiter, +0.46 meter per year at Boca Raton, and -0.9 meter per year at Hollywood. Nearshore volume changes between surveys at Boca Raton were not related to above MSL beach changes. UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGEfWhO" D«(a Entared) .

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The Role of Shell Material in the Natural Sand Replenishment Cycle of the Beach and Nearshore Area between Lake Worth Inlet and the Miami Ship Channel

Cited by 4 publications

References 12 publications

Origin and Distribution of Calcareous Fines on the Carolina Continental Shelf

Origin and Distribution of Calcareous Fines on the Carolina Continental Shelf

Geomorphology and sediments of the nearshore continental shelf : Miami to Palm Beach, Florida / by David B. Duane, Edward P. Meisburger.

Littoral environment observations and beach changes along the southeast Florida coast / by Allan E. DeWall.

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