Morphodynamics and stratigraphy of Big Sarasota Pass and New Pass ebb-tidal deltas, Sarasota County, Florida

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Morphodynamics and stratigraphy of Big Sarasota Pass and New Pass ebb-tidal deltas, Sarasota County, Florida

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Title:
Morphodynamics and stratigraphy of Big Sarasota Pass and New Pass ebb-tidal deltas, Sarasota County, Florida
Creator:
Kowalski, Katherine A.
Place of Publication:
Tampa, Florida
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University of South Florida
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English
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x, 144 leaves : ill. ; 29 cm.

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Subjects / Keywords:
Inlets -- Florida -- Sarasota County ( lcsh )
Coast changes -- Florida -- Sarasota County ( lcsh )
Dissertations, Academic -- Geology -- Masters -- USF ( FTS )
Geology, Stratigraphic -- Florida -- Sarasota County ( lcsh )

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General Note:
Thesis (M.S.)--University of South Florida, 1995. Includes bibliographical references (leaves 97-101).

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University of South Florida
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Universtity of South Florida
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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
022138065 ( ALEPH )
34673021 ( OCLC )
F51-00024 ( USFLDC DOI )
f51.24 ( USFLDC Handle )

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MORPHODYNAMICS AND STRATIGRAPHY OF BIG SARASOTA PASS AND NEW PASS EBB-TIDAL DELTAS, SARASOTA COUNTY, FLORIDA by KATHERINE A. KOWALSKI A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science Department of Geology University of South Florida December 1995 Major Professor: Richard A. D av is Jr., Ph D

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Graduate School University of South Florida Tampa, Florida CERTIFICATE OF APPROVAL Master's Thesis This is to certify that the Master's Thesis of KATHERINE A. KOWALSKI with a major in Geology has been approved by the Examining Committee on August 21, 1995 as satisfactory for the thesis requirement for the Master of Science degree Examining Committee: Major Professor: Richard A. Davis, Jr., Ph.D. Member: Peter Harries, Ph.D. Member: Albert C. Hine, Ph.D.

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ACKNOWLEDGMENTS I would like to sincerely thank Dr. Richard A. Davis, Jr. for his guidance throughout this project. I am also grateful to Dr. Peter Harries and Dr. Albert C. Hine for serving as thesis committee members. This research is part of the West-Central Florida Coastal Studies funded by the United States Geological Survey. I am grateful to the other members of this project for their cooperation and sharing of information, specifically Stan Locker and Dave Twichell. I would like to extend special thanks to my fellow members of the USF Coastal Research Laboratory for their assistance with the field work needed to complete this project: John Cargill, Megan FitzGerald, John Nash, John Pekala, Peter Sedgwick, Eric Shock, Brad Silverman, David Ufnar, Ping Wang, and Amy Welty. And I wish to especially acknowledge my parents for their love, support and plane tickets, and Josh for his long distance love and support.

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TABLE OF CONTENTS LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . iv LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . Vll ABSTRACT ................................................. mv INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . 1 Objectives . . . . . . . . . . . . . . . . . . . . . . . 1 Geographic Setting and Description of Study Area . . . . . . . . . 4 West-Central Florida . . . . . . . . . . . . . . . . . 4 New Pass and Big Sarasota Pass . . . . . . . . . . . . . 6 Physical Processes in the Study Area . . . . . . . . . . . . . . 7 Previous Work ............................................ 10 EbbTidal Delta Morphology . . . . . . . . . . . . . . 10 Sedimentology and Hydrodynamics of Tidal Inlets . . . . . . 15 EbbTidal Delta Stratigraphy . . . . . . . . . . . . . . 17 New Pass and Big Sarasota Pass Studies. . . . . . . . . . 18 PROCEDURES ................................................ 21 Field Methods . . . . . . . . . . . . . . . . . . . . . 21 Surface Samples . . . . . . . . . . . . . . . . . . 21 Vibracores . . . . . . . . . . . . . . . . . . . . 21 Tidal Currents . . . . . . . . . . . . . . . . . . . 26 Pathometer Traces . . . . . . . . . . . . . . . . . . 27 Seismic Surveys. . . . . . . . . . . . . . . . . . . 28 Laboratory Methods . . . . . . . . . . . . . . . . . . . . 30 Aerial Photographs . . . . . . . . . . . . . . . . . 30 Surface Samples . . . . . . . . . . . . . . . . . . 31 Stratigraphic Description and Sampling of Vibracores . . . . . 32 Tidal Prism . . . . . . . . . . . . . . . . . . . . 34 PROCESSES . . . . . . . . . . . . . . . . . . . . . . . . . 36 Tide-Dominated Processes . . . . . . . . . . . . . . . . . 36 Tidal Currents and Prism. . . . . . . . . . . . . . . . 42 Wave-Dominated Processes. . . . . . . . . . . . . . . . . 50 Sediment Budget . . . . . . . . . . . . . . . . . . . . . 52 ii

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HISTORICAL DEVELOPMENT OF NEW PASS AND BIG SARASOTA PASS .. 54 Origin of New Pass and Big Sarasota Pass ........................ 54 Sequential Analysis of Aerial Photographs . . . . . . . . . . . . 54 New Pass .......................................... 55 Big Sarasota Pass . . . . . . . . . . . . . . . . . . 61 Historical Summary . . . . . . . . . . . . . . . . . . . . 64 STRATIGRAPHY ............................................... 68 Lithofacies . . . . . . . . . . . . . . . . . . . . . . . 68 Quartz Sand Facies . . . . . . . . . . . . . . . . . 69 Description . . . . . . . . . . . . . . . . . . 69 Interpretation . . . . . . . . . . . . . . . . . 69 Shelly Facies ........................................ 70 Description .................................... 70 Interpretation . . . . . . . . . . . . . . . . . 72 Muddy Sand Facies . . . . . . . . . . . . . . . . . 73 Description .................................... 73 Interpretation . . . . . . . . . . . . . . . . . 73 Modem EbbTidal Delta Deposits . . . . . . . . . . . . . . . 7 4 Bedrock Topography. . . . . . . . . . . . . . . . . . . . 76 GEOLOGIC HISTORY OF NEW PASS AND BIG SARASOTA PASS ........ 88 CONCLUSIONS ............................................... 95 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . 97 APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . 102 APPENDIX 1. CORE LOGS . . . . . . . . . . . . . . . . 103 APPENDIX 2. SEDIMENT ANALYSIS OF VIBRACORE SAMPLES . 128 APPENDIX 3. SEDIMENT ANALYSIS OF SURFACE SAMPLES . . 134 APPENDIX 4. DISTRIBUTION OF SURFACE SEDIMENTS . . . . 138 APPENDIX 5. TIDAL PRISM CALCULATIONS . . . . . . . . . 142 lll

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Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. LIST OF FIGURES Location Map of Sarasota Bay, Aorida with Barrier Islands and Inlets. . . . . . . . . . . . . . . . . . . . . 2 Map of EbbTidal Deltas of Big Sarasota Pass and New Pass constructed from 1993 Aerial Photographs. . . . . . . . . . 3 Tidal Range Verses Wave Height with the West-Central Aorida Coast Plotted in the Mixed-Energy Field (modified from Davis and Hayes, 1984) . . . . . . . . . . . . . . . . . . 4 Sea-Level Curves: (A) from Southern Aorida (Scholl and Stuvier, 1967), (8) from Stapor et al. (1988, 1991). . . . . . . . . . 10 Components of the EbbTidal Delta, Terminology taken from Hayes (1975). . . . . . . . . . . . . . . . . . . . 12 Inlet Classification by Davis and Gibeaut (1990) ............... 14 Stratigraphy of Ebb-Tidal Deltas: (A) North Edisto Inlet Ebb-Tidal Delta, South Carolina from Imperato et al. (1988), (8) Stratigraphic Facies Model from Cuffe (1991) . . . . . . . . . . . . 19 Location Map of Surface Samples at Big Sarasota Pass. . . . . 22 Location Map of Surface Samples at New Pass. . . . . . . . 23 Location Map of Vibracores, Current Meters, and USACE Cores at Big Sarasota Pass. . . . . . . . . . . . . . . . . 24 Location Map of Vibracores and Current Meters at New Pass ...... 25 Map of Study Site showing Location of Seismic Lines collected and Seismic Cross-sections (A-A', B-B', C-C, D-D') ............ 29 lV

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Figure 13. Figure 14. Figure 15. Figure 16. Figure 17. Figure 18. Figure 19. Figure 20. Figure 21. Figure 22. Figure 23. Figure 24. Figure 25. Figure 26. Figure 27. Figure 28. Compaction Values of Vibracores ......................... 33 Time-Velocity Curve illustrating Time-Velocity Asymmetry ....... 38 Map of Surface Samples showing Weight Percent Gravel at Big Sarasota Pass. . . . . . . . . . . . . . . . . . 40 Map of Surface Samples showing Weight Percent Gravel at New Pass .......................................... 41 Plot of Tidal Currents at New Pass, 10/22-23/94 ............... 42 Plot of Tidal Currents at Proximal Area of Big Sarasota Pass, 8/18-19/94. . . . . . . . . . . . . . . . . . . . . 43 Map of Location and Orientation of Bedforms. . . . . . . . 44 Pathometer Traces from Proximal Area of Big Sarasota Pass: (A) Ebb, (B) Flood. . . . . . . . . . . . . . . . . . 45 Pathometer Traces from Distal Areas: (A) Big Sarasota Pass, (B) New Pass. . . . . . . . . . . . . . . . . . . . 46 Plot of Tidal Currents at Distal Area of Big Sarasota Pass, 8/18-19/94. . . . . . . . . . . . . . . . . . . . . 47 Map of Study Site with Longshore Transport Direction and Tidal Prisms ............................................ 49 1888 Map of Study Site showing the First Documented Morphology of New Pass and Big Sarasota Pass. . . . . . . . 56 Morphologic Development of New Pass EbbTidal Delta, 1948-1993, with Vibracore Locations. . . . . . . . . . . . 58 Morphologic Development of Big Sarasota Pass EbbTidal Delta, 1948-1977, with Vibracore Locations. . . . . . . . . . . . 62 Morphologic Development of Big Sarasota Pass EbbTidal Delta, 1983-1993, with Vibracore Locations ....................... 65 Photographs of Shell Beds: (A) Type 1 Shell Bed in Vibracore BSP-14 from 150 em to 180 em, (B) Type 2 Shell Bed in Vibracore BSP-7 from 180 em to 230 em .................... 71 v

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Figure 29. Map of Big Sarasota Pass with Thickness of the Modern Ebb-Tidal Delta in Meters. . . . . . . . . . . . . . . 75 Figure 30. Cross-section 1-1' across the EbbTidal Delta of Big Sarasota Pass from Lido Key to the Gulf of Mexico. . . . . . . . . . 77 Figure 31. Cross-section 2-2' across the Ebb-Tidal Delta of New Pass, from Longboat Key to the Gulf of Mexico. . . . . . . . . . 78 Figure 32. Cross-section 3-3' across the Proximal Area of the Big Sarasota Pass EbbTidal Delta. . . . . . . .. . . . . . . . . . 79 Figure 33. Cross-section 4-4' across the Proximal Area of the New Pass EbbTidal Delta. . . . . . . . . . . . . . . . . . . 80 Figure 34. Map of Bedrock Topography of Sarasota Bay and Surrounding Areas, modified from Knowles (1983) ...................... 81 Figure 35. Seismic Line C: (A) Analog Print, (B) Interpreted Section. . . . 83 Figure 36. Seismic Line D: (A) Analog Print, (B) Interpreted Section. . . . 84 Figure 37. Seismic Line A: (A) Analog Print, (B) Interpreted Section ........ 85 Figure 38. Seismic Line B: (A) Analog Print, (B) Interpreted Section. . . . 86 Figure 39. Map of Northern Siesta Key with Beach-Ridge Sets Mapped from 1948 Aerial Photographs, from Stapor et al. (1988) ......... 90 Figure 40. Geologic Reconstruction of the Study Site from 3,000 Yrs B.P to 1,000 Yrs. B.P ............. ............. . ....... 91 Figure 41 Geologic Reconstruction of the Study Site from 500 Yrs. B.P. to the Present . . . . . . . . . . . . . . . . . . . 94 vi

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LIST OF TABLES Table 1. Mean Significant Wave Height (meters) by Month for 1956-1975 from Hubertz and Brooks (1989). . . . . . . . . 8 Table 2. Aerial Photograph Coverage of Big Sarasota Pass and New Pass. . . . . . . . . . . . . . . . . . . . . . . 31 Table 3. Bedform Spacing and Height at New Pass and Big Sarasota Pass. . 48 Table 4. EbbTidal Delta Area, Volume, and Tidal Prism from 1888 to 1987 from Davis and Gibeaut (1990), 1994 Data from this Study. . . . . . . . . . . . . . . . . . . . . 55 Table 5. History of Dredged Quantity and Placement for New Pass, from CPE (1993b). . . . . . . . . . . . . . . . . . 57 vii

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MORPHODYNAMICS AND STRATIGRAPHY OF BIG SARASOTA PASS AND NEW PASS EBB-TIDAL DELTAS, SARASOTA COUNTY by KATHERINE A. KOWALSKI An Abstract Of a thesis submitted in partial fulfillment of the requirements of the degree of Master of Science Department of Geology University of South Florida December 1995 Major Professor: Richard A. Davis, Jr., Ph.D. viii

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The barrier islands and ebb-tidal deltas of the low-energy, microtidal, west central Florida coast exhibit diverse size and morphology. In order to determine the geologic history of the ebb-tidal deltas of Big Sarasota Pass and New Pass, Sarasota County, Florida, an investigation of morphology, stratigraphy, and processes was conducted. Aerial photographs aided in understanding historical morphodynarnics. Cores and high-resolution seismic surveys revealed stratigraphy and current meters measured tidal flux. Inlets have served the tidal flux of the south portion of Sarasota Bay since it was formed 4,000-6,000 years ago. An inlet at New Pass has remained in the same position through time documented by the incised bedrock with complex cut and fill structures and by storm deposits in Sarasota Bay. Big Sarasota Pass attained its present position a minimum of 500 years ago, and New Pass most recently opened in 1848. During recorded times, the most drastic change in the inlets has been through the creation of Lido Key and the dredging of New Pass, in the 1920's, which has drastically changed the hydraulics, sediment transport, and morphology of the inlets and the ebb-tidal deltas. Both of the ebb-tidal deltas are composed of two facies, but the morphology of the deltas determines the organization of the facies and thus the stratigraphy of the deposits. The quartz sand facies is comprised of thick units of fme quartz sand produced in wave-dominated subenvironments of the ebb-tidal delta. The shelly facies is composed of shell beds produced by tidal currents in the marginal flood channels and the main ebb channel. The mixed-energy offset morphology of Big Sarasota Pass l.X

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only produces modern ebb-tidal delta facies in a broad area on the north side of the main ebb channel. In comparison, the tide-dominated morphology of New Pass produces the facies on both sides of the main ebb channel. Abstract Approved : ----------------Major Professor: Richard A. Davis, Jr., Ph.D. Professor, Department of Geology I ( Date Approved: !Jb:}/9S I X

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INTRODUCTION Tidal inlets are passes between barrier islands through which tides circulate water of back-barrier bays or estuaries with open bodies of water such as an ocean or mediterranean. Ebb-tidal deltas are sediment accumulations that form seaward of the inlet and are major sites of sand accumulation on the inner continental shelf of the Atlantic and Gulf Coasts of the United States. 1 Big Sarasota Pass and New Pass are located in west-central Florida (Figure 1) where they serve as tidal conduits between Sarasota Bay and the Gulf of Mexico. New Pass separates Lido Key from Longboat Key to the north and Big Sarasota Pass separates Lido Key from Siesta Key. The two ebb-tidal deltas are very different in their size and shape (Figure 2). New Pass been repeatedly opened by storms and subsequently closed (Knowles, 1983), while the origin and history of Big Sarasota Pass is unknown. Objectives The objectives of this study are two -f old: 1) to chronicle the morphologic development of the ebb tidal deltas located at Big Sarasota Pass and New Pass, and 2) to analyze the similarities and differences in the tidal flow, morphology, stratigraphy, and history, of the two ebb-tidal deltas. The first was accomplished by examining

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Gulf of Mexico Sarasota Bay Longboat Key New Pass Big Sarasota Pass Siesta Key 5 kilometers ... ..., .. .. .. -.. / 2 Figure 1. Location Map of Sarasota Bay, Florida with Barrier Islands and Inlets

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3 New Pass Big Sarasota Pass \ :-. : Key 1 k ilometer Fig u re 2. Map of Ebb-T id a l D e lt as of B ig Sarasota P ass and New Pass constru c t e d from 1993 Aeria l P h o tographs.

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4 aerial photographs and historical maps. The second objective was accomplished by investigating the modem processes, and by describing and interpreting the stratigraphy of the ebb-tidal deltas. Geographic Setting and Description of Study Area West-Central Florida The west-central Florida barrier island chain consists of 29 barrier islands and 30 tidal inlets and has the most diverse morphology of any barrier system in the world (Davis, 1989). It is a mixed-energy coast (Davis and Hayes, 1984) with a tidal range of <1m and mean annual breaker heights of approximately 30 em (Tanner, 1960) (Figure 3). 5 _4 !. "' <.'l n .... 2 z "' "' ::;: 700 200 I\1EAP-l WAVE HEIGHT (cmj Figure 3. Tidal Range Verses Wave Height with the West-Central Florida Coast plotted in the Mixed Energy Field (modified from Davis and Hayes, 1984 ).

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The overall low-energy nature of the west -central Florida coast pennits local variation in the size of back-barrier bays and shoreline orientation and has significant morphological consequences on the barrier islands and ebb-tidal deltas. The sediments of west-central Florida are dominated by well-sorted, rounded, fme-grained quartz sand (Davis et al., 1982). The quartz sand is most likely derived from reworked Quaternary coastal and terrace deposits during the later part of the Holocene transgression because there is no significant contribution of sediment to the open coast from a landward source (Davis, 1989). Other constituents of the sediment include mud, mostly of biogenic origin (Evans et al., 1985), and shell or shell fragments of gravel and sand size. 5 The Holocene and Pleistocene sediments form a thin layer (0 to 20 m) which unconformably overlies the shallow Miocene bedrock of the west-central Florida coast The Holocene sediments typically overlie a thin, discontinuous layer (<1 m) of Pleistocene sands or clays (Gibbs, 1991; Davis and Kuhn, 1985; Brame, 1976), but can also occur directly on pre-Quaternary carbonate rocks (Cuffe, 1991) Miocene carbonate rocks in the area are part of a large tectonically stable carbonate platform, the Florida Platform, which includes the entire Florida peninsula and the adjacent West Florida Shelf. The shallow bedrock is an important control on coastal morphology which influences the location of barrier islands and provides stability for large inlets which have become incised into the more-resistant strata (Davis, 1989).

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6 New Pass and Big Sarasota Pass New Pass was formed by a breach of southern Longboat Key caused by a hurricane in 1848 (Harvey, 1982 in CPE, 1993b; Knowles, 1983). Lido Key was formed in the 1920's when John Ringling filled in a small group of mangrove islands and shallow sea grass beds known as Cerol Isles (CPE, 1993b). At that same time, initial dredging of New Pass was performed by the City of Sarasota. In 1964, New Pass was initially authorized as a Federal navigation project and the U.S. Army, Corps of Engineers (USACE) performed a maintenance dredging operation on the inlet. Subsequent dredging operations were conducted in 1973, 1977, 1982, and 1990-1991 (CPE, 1993b). New Pass has a mixed-energy, straight morphology (Davis and Gibeaut, 1990) The ebb-tidal delta is fairly small covering an area of 9.65xl05 m2 The inlet is 170 m wide at the throat and has a spring tidal prism of 1.78x107 m3 The net littoral drift is 45,840 m3/yr toward the south (Davis and Gibeaut, 1990). The inlet has been dredged a minimum of eight time from the 1920's to the present (CPE, 1993b). The origin of Big Sarasota Pass is unknown. The inlet morphologically classified as mixed-energy offset by Davis and Gibeaut (1990). The ebb-tidal delta covers an area of 3.105xl06 m2 The inlet is 570 m wide at the throat, has an average depth of 3.9 m (Davis and Gibeaut, 1990), and the spring tidal prism is 3.49x107 m3 The net littoral drift is 45,840 m3/yr toward the south. The only human modification to Big Sarasota Pass has been the armoring of the Si esta Key shoreline adjacent to the

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main ebb channel of Big Sarasota Pass conducted in the 1940's in order to stop the southerly migration of the inlet. Physical Processes in the Study Area 7 Tides in the study area are a mixture of semi-diurnal and diurnal; during part of the month, two high and two low tides occur each day, while during the rest of the month only one high and one low tide occur each day. The mean diurnal tidal range is 77 em (Davis and Gibeaut, 1990) and the spring range is 91 em (NOAA, 1994). Mean high water is 34 em above NGVD (National Geodetic Vertical Datum) and the mean low water is 8.2 em below NGVD (NOAA, 1992, in CPE, 1993b). Wind direction changes seasonally along the west coast of Florida. During the winter months predominant winds are from the northeast and north, while during the remainder of the year prevailing winds are from the east and the south. Winds blowing from the northeast, east and southeast blow offshore and have little effect on coastal processes; winds blowing from the southwest, west and northwest flow across the Gulf of Mexico and are able to generate waves which approach Florida's Gulf Coast. Periodic frontal systems move down from the western Gulf states and across the Florida peninsula during winter months and produce strong northwesterly winds as the weather system passes the west coast. Information of wind regime was determined from climate data compiled by the Wave Information Studies (WIS) for the years 1956-1975. Winds from the northwest,

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north, northeast, and east average 10-15 knots, while winds from the southeast, south, southwest, and west average 5-10 knots (Hubertz and Brooks, 1989, in CPE, 1993b). Most of the west coast of Florida experiences low wave energies as a result of the broad, shallow shelf and the limited fetch of the Gulf of Mexico. The mean significant wave height in open water is 0.8 meters and the mean peak wave period is 4.8 seconds. The largest percentage of the waves striking the shore are from the northwest. The standard deviation of the wave heights is small (0.3 m), which indicates that similar wave heights are encountered throughout the year. The largest significant wave heights and wave periods are 3.0 m and 9.1 sec, respectively. The average directions associated with these largest wave heights are from 280 degrees. Table 1 presents monthly average wave heights for all twenty years of the WIS wave data (Hubertz and Brooks, 1989 in CPE, 1993b). Table 1. Mean Significant Wave Height (Meters) by Month for 1956-1975 from Hubertz and Brooks (1989). an Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1.0 1.0 0.9 0.8 0.7 0.6 0.5 0.6 0.7 0.9 1.0 1.0 Hurricane season lasts from June through November. Tropical storms and hurricanes greatly increase the magnitude of the processes which affect the coast. During these storms, on average, gale force winds (>34 knots) can be expected from one out of every five tropical storms or hurricanes and hurricane force winds (>64 8

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knots) occur in one out of every 20 (Brand, 1990). The storms result in large waves and storm surges of 1.5 m or more (Brand, 1990). During the hurricane of 1848, a 4 m storm surge was produced in Tampa Bay (Ludlum, 1963). Harvey (1982) listed 27 tropical storms and hurricanes which passed within 100 miles of Sarasota Bay in the period from 1848-1980 (Knowles, 1983). 9 The wave and storm climate determine the longshore transport which is defmed as the movement of sand within the surf zone in a direction parallel to the beach. The magnitude of transport depends primarily on the incident wave height and wave angle. Because sediment transport is directly dependent on the local wave climate, there are seasonal variations in this transport, whether it be a change in magnitude, a shift in direction or a combination of both. Due to the seasonal variation, it is common for a few episodic events to account for a large proportion of the transport for any particular year. The overall pattern of longshore transport in the study area is from north to south with some reversals occurring at inlets and headlands. Littoral transport at Big Sarasota Pass and New Pass is 45,840 m3/yr to the south (Davis and Gibeaut, 1990). There are numerous models for sea-level changes in the Holocene which depict a gradual rise of sea-level to its present position. The model developed by Scholl and Stuvier (1967) will be used because of its proximity to the field site and reliability of data. The model is based on radiocarbon dates from mangrove peats and calcitic muds from the coastal mangrove swamps of southwest Florida. Approximately 4,400 years ago sea-level was nearly 4 m lower than today. Sea-level rose at a rate of 30 cm/100 years until 3,500 years ago at which time it was 1.6 m below its present position

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10 (Figure 4). The rate of sea-level rise decreased and since 1,700 years ago the rate of rise has averaged only 3 cm/100 years. In conjunction with Scholl and Stuvier (1967), the sea-level curve developed by Stapor et al. (1988) will also be considered. The curve is based on radiocarbon dated shells taken from the beach-ridge sets of Lee and Sarasota County barrier islands. The Stapor et al. (1988, 1991) sea-level curve depicts sea-level fluctuating above and below its present position by approximately 5 m (Figure 4 ). The height of the beach ridge sets is dependent on sea-level and wave height. Therefore the periods of high sea-level depicted by Stapor et al. (1988, 1991) are interpreted as times of increased wave energy and not as sea-level change. Previous Work Ebb-Tidal Delta Morphology A general morphogenetic model for ebb tidal deltas was introduced by Hayes (1975). Ebb-tidal delta components include: 1) a main ebb channel through which ebb currents dominate, 2) channel-margin linear bars which flank the sides of the main channel and are built by the interaction of ebb and flood currents, 3) a relatively steep, seaward-sloping terminal lobe which is deposited at the seaward end of the main ebb channel due to the diffusion of tidal currents flowing out of the inlet, 4) flanking swash platforms and individual swash bars which are built up by waves, and 5)

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A) B) !>000 0 (/) t-. w :::!!, j I 3 J i I 4 4 YEARS B P 4000 3o00 ____ 2000 .b .tj .. r / I -/ I I I I k-' / I __.__ I lOCO 3000 2000 1000 0 I I (.) -5 ul WULFERT _ > 1)1 g; ,, LACOU: i --::S-:-A.,.-NI...,-8-EL_I_ BUCK KEY SANIBEL II : 3 :E' 0 >I l 2 l 3 4 s L 5 1-1 I Ill r s I : 0 7 ; :;:: 8 ; o 1 0 I 11T1 r 9 10 : 12 r 13 14 11 Figure 4. Sea-Level Curves: (A) from Southern Florida (Scholl and Stuvier, 1967), (B) from Stapor et al. (1988, 1991).

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marginal flood-dominant channels which allow early flood currents to enter the inlet around the deltas outer margins (Figure 5). l)t '. \ "\ \ '-.. ', SPIT\ .. )'-, '/SWASH BARS LA -'--) ', '. I I I EBBTIDAL : SWASH -I ,1 ,' PLATFORM -.) I \ DELTA ... .... _'"'.::.c..:--c...::>-----, LINEAR BARS <.,'',-, /) ..-..; t:::> LOBE r-7 ,, t, ... / ,) ,, ,..."":\ 1 ,/ CHANNEL I I (I I I I' I I tJ ,' f EBBTIDAL DELTA ' I I I I I Figure 5. Components of the Ebb-Tidal Delta Taken from Hayes (1975). Shape categories of the gross morphology of tidal inlets and their associated ebb-tidal deltas have been developed by Hayes et al. (1970), Oertel (1975), Lynch Blosse and Kumar (1976), Hayes (1975, 1979), Hubbard et al (1979), and Gibeaut 12 and Davis (1993). Hayes (1975, 1979) recognized differences that existed in tidal delta and barrier island configurat i o ns al ong coast lines and created a classification s yst e m

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The classification examined areas of moderate wave energy, and was based on morphology and tidal range. Microtidal {< 2m tidal range) morphologies are characterized by long, narrow islands and widely spaced tidal inlets. The tidal inlets and ebb-tidal deltas are considered to be small to absent and wave dominated, therefore insignificant. Mesotidal (2-4 m tidal range), morphologies are characterized by drumstick shaped barriers separated by numerous tidal inlets. The ebb-and flood tidal deltas are large and well developed and are considered to be tide-dominated. In macrotidal {>4 m tidal range) regions barrier islands and tidal deltas generally do not develop. Through examination of areas with high and low wave energy, Davis and Hayes (1984) have demonstrated that barrier island, inlet, and ebb-tidal delta morphology is dependent on the relative wave or tide dominance of the setting rather than on the absolute tidal range. 13 Other factors determining size and shape of ebb-tidal deltas have been investigated by numerous researchers. Walton and Adams, (1976) determined that the size of the ebb-tidal delta is related to the tidal prism of the inlet rather than the tidal range entirely. The tidal prism is determined by the tidal range in combination with the drainage area of the inlet. The morphology is determined by numerous other factors. Oertel (1977) and Hubbard et al. (1979) noted the importance of the interaction of wave and tidal activity. Sha (1989) discussed the interaction of tidal prism and wave induced longshore currents. Davis and Gibeaut (1990) created a classification based on morphology and described how the morphological variations are due to the rel a tive magnitud e of the wave and tidal activity The classification

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14 describes four inlet types: tide-dominated, wave-dominated, mixed-energy offset, and mixed-energy straight (Figure 6). An important aspect of any inlet and ebb-tidal delta morphology is that it can change through time. Tide-domina ted ... I I -I I I I .. -----' '\'.,. Mixed Energy Straight ,' , '' I If 'J Wave-dominated ,' .. ,.,., I u t .. I ... ' ... \ .. ... ' \ ' I I I \ I Figure 6. Inlet Oassification by Davis and Gibeaut (1990). Hatching indicates areas along the shoreline that are mosst affected by tidal inleeet dynamics. The ocean or gulf is to the left and the bays are to the right. I I I I

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Sedimentology and Hydrodynamics of Tidal Inlets Studies of the physical processes affecting ebb-tidal delta sedimentation have greatly increased our knowledge about the delta accumulations. The pattern of flow and channeling in and around tidal inlets have been studied by Price (1963), who described the flaring "tidal jet" which is created by tidal currents issuing through an inlet. This jet-type flow is created by elevation differences on opposite sides of the barrier islands during the tidal cycle which forces water to flow centripetally into the inlet and to flare out at 20 degrees once beyond the constriction of the inlet. 15 Other hydrodynamic studies of tidal flow and tidal inlet/ebb-tidal delta sedimentation have been performed by Bruun and Gerritsen (1959), Hayes et al. (1970), Oertel (1972), Byrne et al. (1975) and Hine (1975) among many others. Bruun and Gerritsen (1959) demonstrated that littoral drift and tidal flow control sediment bypassing the ebb-tidal deltas, either by migration of bars or by tidal flow. Hayes et al. (1970) demonstrated that wave activity mobilizes sediment from the distal platform of the ebb-tidal delta and sediment is then welded onto the downdrift island. A general pathway by which sand is bypassed around an ebb-tidal delta was developed by Oertel (1972) and by Hine (1975). Sand is transported along the shore by longshore currents. When it encounters the ebb-tidal delta most of the sand enters the main ebb channel and is transported seaward to the terminal lobe. Once on the terminal lobe, the sand can be remobilized by waves and incorporated into the actively migrating swash bars and is then transported landward or back into the main ebb channel. This pathway

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16 demonstrates how the middle and distal parts of the delta are dominated by wave activity and the proximal portion is dominated by tidal activity. Byrne et al. (1975) described the changes in inlet flow characteristics and sediment transport during changes in tidal range. Davis and Fox (1981) determined that tidal currents only have an influence within a few hundred meters of the inlet, disrupting wave and longshore activity in that area. Sedimentological characteristics and bedform distribution have also been studied extensively. Allen (1971) determined that grain size parameters at estuary entrances were associated with different zones. The mean grain size and skewness of sands are inversely proportional, while sorting is directly proportional, to the ratio of wave to tidal activity. Areas dominated by tidal currents are characterized by coarser grain sizes, relatively poor sorting and bed-load transport, whereas areas dominated by wave energy are characterized by finer grain sizes, well-sorted sands, and suspended load transport. Boothroyd and Hubbard (1975) described the sequence of bedforms which are generated in the intertidal and shallow subtidal zones of mesotidal estuaries and have shown that the bedforms generated are governed by the maximum current velocities, the velocity asymmetry and the duration of flow above a given velocity. Also important is the changing orientation of the bedforms through the rise and fall of the tide. Reversal of bedforms will occur if the hydraulic regime which created the bedforms is reached less than half way through the ebb of flood cycle (Allen, 1974). Process-response or geomorphic cycling studies of ebb-tidal deltas have been performed by FitzGerald (1976), Finley (1975, 1978), Oertel (1977), FitzGerald and

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Nummedal (1983), FitzGerald (1984), and Sha (1989). Finley (1975) and FitzGerald and Nummedal (1983) recorded changes in morphology and inlet flow characteristics as a result of increased sediment input into the inlet system. FitzGerald (1976, 1984) described a cycle of the main ebb channel shifting in response to migration and welding of swash bars to the adjacent shoreline. Oertel (1977) and Sha (1989) described the cycles of landward migration of shoals and associated channel changes. Finley (1978) used surf zone wave observations to determine longshore energy flux and has shown that a close relationship exists between wave-energy, longshore sediment supply and ebb-tidal delta morphology. EbbTidal Delta Stratigraphy 17 Although numerous studies describe ebb-tidal delta processes and resulting morphology, relatively few have described ebb-tidal delta stratigraphy. Most stratigraphic descriptions of ebb-tidal delta deposits have been compiled from shallow box cores and observations of surface features. More recent studies have used vibracores to describe the stratigraphy of ebb-tidal deltas. Imperato et al. (1988) described the stratigraphy and sedimentary characteristics of the mesotidal ebb-tidal delta at North Edisto Inlet, South Carolina. Cuffe (1991) created a stratigraphic facies model based on the ebb-tidal delta of Hurricane Pass in the west-central Florida barrier island chain. Both authors were able to distinguish different depositional environments within the ebb-tidal deltas including the main ebb channel, flood channel, and swash

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18 bar and swash platform deposits (Figure 7). The stratigraphic sequences depicted by the authors are punctuated by shell beds which are at the base of fining-upward sequences. The stratigraphy consists of cross-bedded, coarse-grained, channel deposits and planar horizontally laminated, fme-grained, swash platform and terminal-lobe deposits. The preservation potential of ebb-tidal deltas is fairly low. It is controlled by the position of the upperand lower-boundary surface of the ebb-tidal delta system relative to 1) the rate of sea level change, 2) the rate of sediment supply, 3) the open marine wave and current energy, and 4) the tidal prism through the inlet (Sha and deBoer, 1990). New Pass and Big Sarasota Pass Studies Numerous studies have been conducted on New Pass and Big Sarasota Pass by Coastal Planning and Engineering (CPE) for the City of Sarasota (CPE, 1993a; CPE, 1993b; CPE, 1993c). The results of wave refraction modelling performed on Big Sarasota Pass and New Pass predict sediment transport direction and volumes (CPE, 1993c). The inlet management plans for Big Sarasota Pass and New Pass (CPE, 1993a; CPE 1993b) detail the history of the inlets and adjacent shorelines through a compilation of beach profile and bathymetric survey data taken from numerous sources. Data on the stratigraphy of Big Sarasota Pass ebb-tidal delta are available

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A) B) 1.0m O.Sm Om ' I I I C M F SAND SIZE PROXIMAL FORESHORE SWASH BAR ABANDONED MARGINAL FLOOD CHANNEL ACTIVE MARGINAL FLOOD CHANNEL SHOREFACE SHELLS T BURROWS I I I C M F SAND SIZE I f'ZJ M F M C G I I I I I ....... ........ .. . . . ... .. . . . . ... .. channel margin linear bar swash. platform marginal flood channel awash platform SWASH SARI SWASH PLATFORM ASANDONEO MAIN EBB CHANNEL ACTIVE MAIN EBB CHANNEL PLEISTOCENE UNDIFFERENTIATED PLANAR BEDDING E1 CROSS BEDDING El "'(.,.-I "'=') :.; , ( ... -........ . . . I 1 I I C M F VF SAND SIZE FLASER BEDDING WAVY BEDDING DISTAL SWASH BAR/ SWASH PLATFORM SHOREFACE ]1111ETER agitated type shell current-generated beds storm-generated shell hash lamlnatJons burrows mottling mud laminae planar horlz. bedding Figure 7. Stratigraphy of Ebb-Tidal Deltas: (A) North Edisto Inlet Ebb-Tidal Delta, South Carolina from Imperato et al. (1988), (B) Stratigraphic Facies Model from Cuffe (1991). 19

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20 through the U.S. Army, Corps of Engineers (USACE). Four cores were taken in 1968 as part of a reconnaissance of the coast, and 19 cores were taken in 1988 in order to analyze the delta's potential as a borrow source for beach nourishment projects The stratigraphy and geologic history of Sarasota Bay and Little Sarasota Bay have been developed by Knowles (1983) and Bland (1985). Both Sarasota Bay and Little Sarasota Bay were formed approximately 4,000-6,000 years ago when sea-level rise slowed resulting in barrier island formation. The barrier islands probably formed seaward of their present location and have migrated landward during a slowly rising sea-level. The history of New Pass has been developed in conjunction with the history of Sarasota Bay. New Pass has been opened by storms three times in its geologic history; 2,270 years ago, 1,320 years ago, and in 1848 (Knowles, 1983).

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21 PROCEDURES Field Methods Surface Samples Surface samples were taken to characterize modem environments within the inlet and ebb-tidal delta system. All of the samples were taken in the spring through fall of 1994. Surface samples were taken using a Petersen sampler. Seventy-eight surface samples were taken in the inlet and ebb-tidal delta of Big Sarasota Pass (Figure 8). Fifty samples were taken at New Pass (Figure 9). Location of the samples was determine-d using Loran navigation. Vibracores Vibracores were taken in order to examine the stratigraphy of the ebb-tidal deltas. The cores were taken in different environments across the ebb-tidal deltas in order to sample different modem and ancient environments. Fifteen vibracores were taken on the ebb-tidal delta of Big Sarasota Pass (Figure 10) and nine were taken at New Pass (Figure 11). A shallow water coring barge was used to take the cores in a method similar to that described by Lanesky et al. (1979). A 5-hp engine was attached

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51 A 9\1. 500 meters 53 .24 .23 .63 59 60 e22 67 2 1 22 Big Sarasota Pass eJH 'S3 J(, e2o el>l! 7 0 Figure 8. Location Map of Surface Samples at Big Sarasota Pass See Appendices 3 and 4 for t extura l analysis.

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500 meters LOngboat Key 40 21. 2 .43 .25 4 24 2 3 41. 22. 46 e4 8 e3s 19. e1s 30 23 Figure 9. Location Map of Surface Samples at New Pass. See Appendices 3 and 4 for textural analysis.

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Big Sarasota Pass + e 8 + + Siesta Key + + + 1+ 500 meters + General Oceanics current meter McBirney current meter + + + + e vibracores + USACE Figure 10. Location Map of Vibracor es USACE Cores, and Current Mete rs at Big Sarasota Pass. 24

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+ 500 meters t Key 6 8 vibracores + General Oceanics c urrent meter Figure 11. Location of Vibracores and Current Meters a t New Pass. 25

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with a 9 m cable to a vibrator head used for cement settling. The vibrator head was then clamped to the top of 7.63 em diameter (3 in.) aluminum irrigation pipes of various lengths that were vibrated down into the sediment. 26 After the pipe was vibrated into the sediment, the compaction of the core sample was determined by measuring the depth to sediment inside the core pipe and outside the core pipe. The difference between the inside and outside measurements is only an estimate of the compaction because redding may have also been a contributing factor. Redding is roughly defmed as the condition where the opening of the core pipe is blocked by a large shell or tightly compacted sediment that prevents more sediment from entering the core pipe as the pipe continues to move down through the surrounding sediment. A large rubber stopper was inserted in the top of the core pipe to prevent slippage and loss of sediment out the bottom of the pipe while it was extracted. The core was extracted using a heavy-duty aluminum tripod with a chain block attached at the apex. The water depth and time of day were recorded at each core location before the core was extracted. The water depth was used in combination with the NOAA Tide Table convention to obtain the elevation of the sediment surface with respect to mean low water (ML W). The location of each core was determined by visual determination of position on aerial photographs and by Loran. Tidal Currents Tidal current velocities and direction were measured and tidal prisms were

PAGE 39

27 calculated in order to understand the hydraulics of the inlets and surrounding areas. Tidal current velocities were measured using General Oceanics, Inc. Niskin Winged current meters and a hand-held Marsh McBirney electromagnetic current meter. The General Oceanics current meter was used with standard fms which enabled it to measure velocities from 0 to 225 crnjsec. The velocity magnitude measurements had an accuracy of +/1 crnjsec and a resolution of +/1 crnjsec. The velocity direction measurements have an accuracy of+/-2 degrees and a resolution of+/-1 degrees. The Marsh McBirney current meter is able to measure velocities from 0 to 300 crnjsec with an accuracy of+/-2% of the reading. All current measurements were taken during spring tidal conditions. Current velocities were measured at six locations at Big Sarasota Pass in the inlet and around the ebb-tidal delta using both types of current meters (Figure 1 0). The General Oceanics meter recorded velocities for twenty-four hours on August 18-19, 1994. Current measurements with the Marsh McBirney meters were taken approximately every forty-five minutes for twelve hours on October 8, 1994. At New Pass, tidal current velocities were measured in two locations using the General Oceanics current meter (Figure 11 ). The meters measured tidal currents for twenty-four hours on October 22-23, 1994. All of the current measurements were taken at 60% water depth which is where the average velocity occurs in the water column. Fathometer Traces The fathometer traces were taken at New Pass and Big Sarasota Pass at

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28 different times during spring tide in order to observe bedforms in the main ebb channels and to obtain cross-sections of the channels for calculation of tidal prisms for each inlet. The traces were taken in conjunction with the deployment of the General Oceanics meters so that current velocity and direction were known at the time the trace was taken and so that tidal prisms could be calculated. The traces were obtained using a Raytheon DE-719B fathometer. Seismic Surveys The seismic surveys collected provided information on the overall geometry and internal features of the ebb-tidal deltas as well as examining the nature of the underlying bedrock. The high resolution seismic data were collected on a cruise of the R/V Bellows during November 7-11, 1994. Figure 12 shows the location of collected seismic lines. Positioning was determined using differential GPS, WGS-84 datum. The source was a Huntec Sea Otter powered at 135 Joules, and an ITI streamer powered at 24 VDC. The source and streamer were towed about a meter apart to prevent the delay in the direct arrival from interfering with the seafloor reflection in shallow water. The digital seismic data were recorded using the Elics Delph system. Acquisition parameters were 400 ms shot rate, 150 ms recording length and 10,000 Hz sample rate.

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A' Siesta Key 0' 1 kilometer Seismic line Seismic cross-section Figure 12. Map of Study Site showing Location of Seismic Lines collected and Seismic Cross-sections (A-A', B-B', C-C', 0-0'). 29

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30 Laboratory Methods Aerial Photographs Vertical aerial photographs and historical charts were collected in order to observe and document morphological changes of the study area through time. Also available are data on shoreline location compiled from historical maps, shoreline survey maps and beach profiles on Longboat, Lido, and Siesta Key. Agencies and companies involved in collecting the data are U.S. Coast and Geodetic Survey, Aorida Department of Natural Resources (Beaches & Shores), National Ocean Surveys, U.S. Army, Corps of Engineers, Coastal Planning & Engineering, Inc., and Applied Technology and Management. Coastal Planning & Engineering, Inc., compiled the information and provided shoreline position and movement for the years 1883, 1942, 1952, 1971, 1974, 1977, 1987 and 1992. Other historical records such as current measurements, construction records and other reports were also used. The shoreline and outlines of the ebb-tidal deltas were digitized from the aerial photographs. The outlines of the ebb-tidal deltas were based on color changes in the water and wave refraction patterns. The quality of the photograph and thus interpretation of the outline of the ebb-tidal delta is dependent on the tidal stage and weather conditions at the time the photograph was taken. The database of aerial photographs used is listed in Table 2.

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31 Table 2. Aerial Photograph Coverage of Big Sarasota Pass and New Pass. LOCATION DATE SCALE New Pass, Big Sarasota Pass 2-2-48 1:20,000* New Pass, Big Sarasota Pass 3-23-57 1:20,000* New Pass, Big Sarasota Pass 12-5-69 1:40,000 New Pass, Big Sarasota Pass 12-19-72 1:24,000 New Pass, Big Sarasota Pass 8-26-74 1:30,000* New Pass, Big Sarasota Pass 12-7-77 1:24,000* Big Sarasota Pass 3-29-83 1:24,000* New Pass 1-15-86 1:24,000* New Pass, Big Sarasota Pass 2-19-93 1:24,000* Indicates photographs that were digitized. Surface Samples All surface samples were rinsed with distilled water three times to remove salt residue. The samples were dried and split using a riffle splitter into small (30 to 50 gm) samples for sieve analysis. These samples were sieved in a rotap using the 1 phi (2 nun) sieve to separate sand from gravel. A 1-gm aliquot from the sand fraction of each sample was settled in an automated 190-cm settling tube to determine textural parameters of the sand. The remainder of the sand was split with one half archived and the other half was weighed, rinsed with HCl to dissolve the CaC03 and then reweighed to determine CaC03 content.

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32 Stratigraphic Description and Sampling of Vibracores The vibracores were cut into 1 m sections to facilitate handling, storage and photography. The casing of each section was cut lengthwise using a circular saw with a curved cutting guide and a carbide-tipped blade. After cutting the pipe, a knife was used to separate the sediment within the pipe. Logging of each core included description of general sediment type (quartz sand, muddy sand, etc.), sedimentary structures (laminations, flasers, bioturbation, etc.), and diversity of invertebrate species. Appendix 1 includes all core logs. The amount of compaction was accounted for in each core log by adjusting to assumed pre-compaction condition. The percentage of compaction was calculated by: % of core compaction= (a/a+b)*100 a= inside depth outside depth b= total length of core recovered The length of core recovered was increased by the compaction value to obtain the original sediment thickness. The percentage of compaction varied from 3 to 59% (Figure 13) in the cores collected. It was decided that in the cores having large compaction values, only 22% of the calculated compaction would be attributed to compaction and the remaining compaction would be attributed to redding. The value of 22% was selected on the basis of the difference in porosity that results from the compaction of particles oriented in a cubic arrangement to particles oriented in a

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Core Compaction 3 .----------------------------------------------. "'2 ..... 0 i zl predominately sandy predominately shelly 0 I H -4 7 10 13 17 20 23 26 29 32 35 38 41 44 47 50 53 % Compaction Figure 13. Compaction Values of Vibracores. 33 rhombohederal arrangement. Cubic packing exhibits a porosity of 48% while rhombic packing exhibits 26% porosity. The 22% difference in porosity should result in an increase of 22% available space. Therefore cores exhibiting large compaction values were only expanded by 22% instead by their calculated compaction values. There is a significant and noticeable distribution of compaction in relation to the content of the cores. The cores consisting of predominately of sand-sized material had 3 to 17% percent compaction. The percentage in cores dominated by larger, shelly material ranged from 33 to 59% (Figure 13). Epoxy peels were made of several cores in an attempt to observe subtle sedimentary structures. The peels were made by covering a section of core with cheese-cloth and then impregnating the cheese-cloth with epoxy. After drying, the

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34 hardened cloth was peeled back with the sediment that had dried to the epoxy-soaked cloth. Loose sediment was removed from the peel. In many cases, fme stratification and shell imbrication were clearly defmed using this method. Several samples were taken from the cores to provide quantitative grain size information (Appendix 2). The samples were taken every 30 to 60 em depending on changes in sedimentary characteristics. The samples were taken as a 2-cm wide layer weighing 40-50 grams. The samples were processed in the same manner as the surface samples. Tidal Prism Tidal prisms for one location at New Pass and two locations at Big Sarasota Pass were calculated using the current data method proposed by Jarrett (1976). This method uses the cross-section of the channel which was obtained from fathometer traces and the velocity of currents measured by the current meters. The average velocity through the cross-section was computed by v IV = R 213fD213 avf!! meas vavg = average velocity through flow section (ft/sec) v meas = measured velocity (ft/sec) R = hydraulic radius (ft) = cross-sectional area (ft2)/ wetted perimeter(ft) D = depth of water at the current meter location (ft)

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35 The average velocity was calculated at 1-hour increments during the tidal cycle. The cross-sectional area was calculated at one hour increments over the tidal cycle by adjusting the area of the flow cross-section for fluctuations in tidal elevation. The discharge was calculated at one hour increments by multiplying the cross-sectional area and calculated average velocities. The discharges for the ebb and flood flows were numerically integrated separately and then averaged to determine the tidal prism. The values resulting from these calculations are in Appendix 5.

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36 PROCESSES The accumulation and characteristics of ebb-tidal delta sediments and ebb-tidal delta morphology are affected by both tideand wave-dominated processes that occur within the vicinity of the inlet. In tide-dominated areas, tidal currents resuspend and transport sediment seaward and landward through the inlet. Sediment is deposited at the end of the tidal jet where the tidal current diffuses and current velocities diminish (Price, 1963). In wave-dominated areas, wave and wave-generated currents erode and transport sediment landward and along shore. Sediment is deposited at a zone of equilibrium (Hubbard et al., 1979) along the margin of the ebb-tidal delta where incoming wave energy is equal to the tidal current energy of the expanding ebb jet, and around the inlet throat where wave-generated, along-shore currents are interrupted by the shore-normal tidal currents flowing through the inlet. Tide-Dominated Processes Tidal range is important to tidal inlet systems because it affects the volume of water that is exchanged through the inlet. The tidal discharge (Q) through an inlet is a function of the mean velocity (V) and cross-sectional area of the inlet (A) such that at any point across the inlet Q= VA. Tidal prism is also dependent upon the size of the estuary; larger estuaries can hold larger volumes of water. This is because only the

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37 volume of water which lies between high and low tide levels will flow through the inlet during the tidal cycle. It is not the deepest estuaries which have the largest tidal prisms, but those which cover the greatest amount of surface area. The size of the tidal prism, not tidal range, controls the size of the ebb-tidal delta. Along microtidal coasts where broad, shallow estuaries exist, large tidal prisms occur even though tidal range is small. An example of this is the west-central Florida coast; the tidal range is less than 1 meter and values for tidal prisms range from 105 to 108m3 (Davis, 1989). Tides produce two other basic phenomena with respect to tidal inlets and ebb tidal deltas: 1) time-velocity asymmetry, and 2) horizontal segregation of flow (Hayes and Kana, 1976; Boothroyd, 1985). Velocity asymmetry means that maximum flood and ebb currents are not the same magnitude (Figure 14) and time asymmetry means that the time of maximum velocities is not the same for flood and ebb within the tidal cycle. Hayes and Kana (1976) describe horizontal segregation of flow as occurring because of the time-velocity asymmetry of inlets. Because maximum ebb currents usually occur late in the tidal cycle as the tide begins to flood strong ebb currents continue to flow through the inlet. As the tide begins to rise, incoming flood currents, attempting to take the path of least resistance, are forced to enter the inlet around its margins, hence segregating ebb and flood flow into separate channels within the inlet system. The examination of bedforms is very important in current studies. Bedforms supply information on the maximum current velocities, the degree of velocity

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TIDE STAGE 80 :'.... 80 /. , Main Ebb Channel 'J ',I u 40 g w > LOW HIGH 0 2 HRS. '-------'-----' LOW m c:c c:c 38 Figure 14. Time-Velocity Curve illustrating Time-Velocity Asymmetry. Note time and magnitude of maximum flood and ebb velocities (from Hayes and Kana, 1976). symmetry, and the duration of flow above a given velocity Reversal of bedforms will occur if the hydraulic regime which created the bedforms is reached less than half way through the ebb or flood cycle. Tirrough examination of the surface sediments at Big Sarasota Pass and New Pass, areas on the ebb-tidal deltas dominated by tidal currents can be mapped. Due to the well-sorted, fme-grained quartz fraction of the sediment, variations in the sediment result from variation in the carbonate fraction. The gravel portion is 100% carbonate, and at many areas of the ebb-tidal deltas a large portion of the sand fraction is carbonate. The carbonate fraction causes coarser grain sizes and poorer sorting of the sediment. These are also characteristics of tidally dominated areas (Allen, 1971). Therefore, mapping of the carbonate fraction reveals areas that are dominated by tidal currents. The distribution of the carbonate fraction is easily seen by the distribution of

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weight percent gravel (Figure 15 and 16). The main ebb channels of both inlets have large values of weight percent gravel, from 20% to 90%. The proximal area of the ebb-tidal delta of Big Sarasota Pass, which has numerous marginal flood channels, 39 also has high values of weight percent gravel. The sand in these tide-dominated areas has a coarse mean grain size, from 1 to 2.5 Q>, and high values of weight percent of carbonate, from 10 to 90%. The species richness in the tide-dominated areas is large, but the assemblage is dominated by Chione cancellata, Tellina sp., and Anadara transversa which are open-marine taxa. The few back-barrier-bay species present are most abundant in surface samples collected in the main ebb channel and in the marginal flood channels. The presence of these species suggests transport from behind the barrier islands; further supporting the tide dominance of the main ebb channel and marginal flood channels. The majority of the shells are abraded, broken, or fragmented, suggesting transport. The spring tide is semi-diurnal with a pronounced inequality between the heights of the highs and lows during one tidal cycle (Figure 17). The two ebb and two flood portions of the tidal cycle are not equal in their length, slope, and magnitude and thus the currents during each portion of the tidal cycle are very different. Of the two ebbing periods, one is dominant with a longer time, greater slope, and larger change in water elevation. The two segments of flooding are close in duration, slope, and change in water elevation.

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I..! I 0.5 6 0.17 1.64 0 14 \.V 0 27 0 6 9 0 .22 0 .14 1.11 0 .09. 0.49 0 .14 0 08 0.58 . 0 00 3 .00 0.50 0.76 0 .68 0 .9 0 1.33 0.43 0 1 4 Big Sarasota Pass :::::: Siesta Key ."'J 1 H6 0 1 2 en1o 0.10 1.22. 500 meters 0 > 5 % weight% gra ve l Figure 15. Map of Surface Samples showing W e ight Percent Gravel at Big Sarasota Pass. 40

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+ Longboat Key tUh :.oo. Hlo . tl.llh 500 meters 0 >5'1., wei ght% gr<1vcl e c il'l l t N Figure 16. Map of Surface Samples showing Weight Percent Crave! <1t New Pass.

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flood ebb New Pass proximal current meter 10/23-23/94 ,-----------------------.-0. 7 0.4 0 3 I -0.6 ......... / .. I I cu .... \ \,
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flood ebb Big Sarasota Pass proximal current meter, 8/18-19/94 0.8 "\ 0 6 \ \ 0 4 0.1 0 10 15 20 25 Time 1--velocity (nils) -water elevation (m) J Figure 18. Plot of Proximal Tidal Currents at Big Sarasota Pass, 8/18-19/94. 43 The proximal portion of the channels at Big Sarasota Pass and New Pass have significant ebb and flood currents, while the distal portion of the channels are ebb dominated. In the proximal portion of the channels (Figure 19), the velocities are symmetrical (Figure 17 and 18). The bedforms change orientation in response to the orientation of the currents (Figure 20). The currents are very asynunetrical and the bedforms do not change orientation over the tidal cycle as compared to the more distal area of the channel (Figure 21). The low flood velocities are not strong enough to change the eblH>riented bedforms. At Big Sarasota Pass the flood velocities only reach 40 em/sec while the ebb velocities reach 100 em/sec (Figure 22). In the distal part of the channel the volume of water ebbing is 1.93xl07 m3 and the flood prism is

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44 Areas of bedforms 1 kilometer and flood oriented only ebb oriented Figure 19. Map of Location and Orientation of Bedforms.

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A) B) -------A-------------------! 17 ______________ _:_, _ ---_-_ ----=---r-----------J _____ --.:.. -----__ -r-----------4 7-.... I -----------48---------I Flood 11 meter 10 meters --. 0 I iliiiiii" =\ ____ _ ..... -\-c:-_ _ i -1----f -: i : __ :__ __ : -__ [ --: Fgure 20. Fathometer Traces from p -1 roxtma Area of Btg Sarasota Pass: (A) Ebb (B) Flo d Se p 0 e tgure 19 for location.

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A) B) Flood 10 meters 11 meter 10 11 meter meters Figure 21. Pathometer Traces from Distal Areas: (A) Big Sarasota Pass, (B) New Pass. See Figure 19 for locations. Traces taken during ebbing tide.

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Big Sarasota Pass distal current meter 8118-19/94 0.4 flood 0 2 0 6 0.4 0 3 0 2 0 1 -1.4 t---+---t---+-f---+----1---+---+----30-40 em/sec, <70-80 em/sec). The high-energy sand waves are characterized by a spacing of > 10 m and a high flow velocity (>70-80 em/sec, may be as high as 150 em/sec) (Boothroyd, 1985)

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48 Table 3. Bedform Spacing and Height at New Pass and Big Sarasota Pass. Height Spacing (meters) (meters) New Pass distal 0.5 5-8 proximal 0.2 0.6 6-18 Big Sarasota Pass distal 0.41 5-46 proximal 0.3 0.8 6-24 The hydraulics of the proximal and distal areas can be further examined through the calculated tidal prisms. The volume flooding the proximal areas is a combination of the volume flooding distal areas and the volume flooding across the swash platform and marginal flood channels. This is especially important at Big Sarasota Pass which has a broad swash platform on one side of the channel. At Big Sarasota Pass the volume of water flooding across the platform contributes two thirds of the tidal prism of the inlet (Figure 23) The numerous channels that dissect the ebbtidal delta of Big Sarasota Pass are flood dominated The flood velocities range from 30 to 75 em/sec while the ebb velocities range from 10 to 40 em/sec. The channel closest to Lido Key has the highest flood currents (75 em/sec) The maximum flood currents occur approximately 2 hours after low tide. The swash platform and marginal flood channels are flood dominated; the flood volume is 3 times the ebb volume. The differences betw ee n the inlets is that New Pass is ebb dominated and Big

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56,633 m3 /yr 1.78xlo7 m3 flood-1.3lxl07 m3 ebb-2 26xl07 m3 ebb-0.99xlo7 m3 direction of tidal currents 1 kilometer direction of longshore transport flood4.07xl07 m3 ebb2.92x107 m3 3.41:Jx1U7 m3 t CJ Siesta Key flood-0.682xl07 m3 eb b -1.93xl07 m3 49 Figure 23. Map of Study Site with Longshore Transport Direction and Tidal Prisms. Values and orientation of longshore transport taken from CPE (1993b ).

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50 Sarasota Pass is flood dominated. At New Pass the velocity and duration of ebb currents as well as the ebb prism are larger than the flood. Maximum flooding currents are 95 em/sec and the maximum ebbing currents are 97 em/sec. The duration of ebbing currents is longer than flooding currents; 13.5 hours as compared to 11.5 hours. The tidal prism of New Pass is 1.78xl07 m3 with a flood prism of 1.31x107 m3 and an ebb prism of 2.26xl07 m3 At Big Sarasota Pass, in the proximal portion of the channel, there is a dominance of flood prism because of the longer flood period; the currents are flood oriented for 13.5 hours and ebb oriented for 11.5 hours. The flood prism is 4.07xl07 m3 and the ebb prism is 2.92xl07 m3 The two inlets may be exchanging tidal flux. Approximately 1.15x107 m3 is flooding through the main channel of Big Sarasota Pass but is not ebbing through the inlet while 0.95xl07 m3 is ebbing through New Pass that is not flooding through the inlet. A likely hypothesis to explain this phenomena is that some of the water that floods through Big Sarasota Pass is ebbing through New Pass. Wave-Dominated Processes Waves and wave-generated currents are the other dominant factors which affect tidal-inlet processes. Sediment is provided to the ebb-tidal delta mainly by the longshore transport of material by wave-generated currents in the surf and swash zones (Boothroyd, 1985). The down-drift transport of sediments carried by these currents is halted at the inlet where stronger tidal currents flow normal to shore Because

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51 incoming waves also refract around the issuing ebb jet the wave approach may be shifted around the vicinity of the inlet and the direction of longshore transport reversed on the down-drift side of the inlet. Where longshore currents are directed into marginal flood channels, they can have an additive effect to flood-tidal currents entering the inlet. Swash currents are generated by breaking waves atop the shoaling sediment accumulations of the ebb-tidal delta and are considered the most important agent in generating migrating bedforms atop the swash platform (Boothroyd, 1985). Swash bar complexes which form atop the swash platform are commonly composed of migrating megaripples or sand waves. These bedforms migrate landward due to the shear stresses set up on the sediment bed as the wave-generated current moves landward. The wave-dominated areas of the ebb-tidal deltas are clearly distinguished by examination of the distribution of the weight percent gravel (Figure 15 and 16). Wave dominated areas are characterized by fme grained, well-sorted sediments (Allen, 1971 ). The weight percent gravel of the sediment in these areas is <2%. The sand portion is fme grained (2 .5 to 2.9 ) and the weight percent of carbonate of the sand portion varies from 0 to 8%. The faunal assemblage in the wave-dominated areas is low in abundance and in species richness. The most abundant species being Lucina floridiana, followed by Donax variablis, Echinodermata, and Tellina sp .. The tidal currents and refraction of waves around the ebb-tidal deltas affect the direction and rates of longshore transport. The overall pattern of longshore transport in the study area is 45,840 m3/yr to the south (Davis and Gibeaut, 1990; CPE, 1993b ). A

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52 wave refraction model was applied to New Pass and Big Sarasota Pass by Coastal Planning & Engineering (1993c). The model results include direction and volume of longshore transport. Approximately 1,200 m south of New Pass there is a reversal in the longshore transport (Figure 23). At this nodal point there is a net transport divergence, north of the point the transport is to the north, south of the point the transport is to the south. This area of shoreline is characterized by erosion. At Big Sarasota Pass there is also a reversal of transport direction just south of the inlet. Sediment transport along the northern 760 m of Siesta Key is toward the north (CPE, 1993a). South of that point the transport is southerly. Sediment budget A sediment budget for the study site was developed by Coastal Planning & Engineering (1993c) from results of the wave refraction model and beach profile data from 1974 to 1992. An estimated 56,633 m3/yr moves south off Longboat Key into New Pass and the ebb-tidal delta. The ebb-tidal delta receives 13,010 m3/yr from the south. An average 57,398 m3/yr of material was dredged from the navigation channel. Most of the dredged material, 52,041 m3/yr, was placed on Lido Key and 5,357 m3/yr was placed on the southern end of Longboat Key The net result was that the New Pass ebb-tidal delta has gained approximately 12,245 m3/yr. From comparison of ebb tidal delta surveys from 1953-1991, the northern part of the shoal gained 2,296 m3/yr

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53 and the southern portion gained 13,010 m3/yr, while the middle portion was dredged of 3,061 rn3/yr. The northern one mile section of Lido Key experienced 9,949 m3/yr of accretion. Sand is being transported out of the inlet by tidal currents and is converging with transport that is occurring along the shore by longshore currents (CPE, 1993b ) The rest of the island has lost a total of 37,500 m3/yr to erosion. The amount of net southerly littoral drift leaving Lido Key and entering Big Sarasota Pass and the ebb tidal delta is calculated to be 76,531 m3/yr. The increased net southerly drift rate is due to the shading of southwest waves by the large ebb-tidal delta of Big Sarasota Pass (CPE, 1993b). Wave refraction produces a reversal of longshore transport approximately 1 km south of the north tip of Siesta Key.

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54 HISTORICAL DEVELOPMENT OF NEW PASS AND BIG SARASOTA PASS Origin of New Pass and Big Sarasota Pass New Pass was formed by a hurricane breaching southern Longboat Key in 1848 (Harvey, 1982 in CPE, 1993b; Knowles, 1983). The hurricane approached the coast from the south or southeast and produced an approximate 4 m storm surge in Tampa Bay (Ludlum, 1963). Hurricane generated tidal inlets are not uncommon, examples are found on the Atlantic (El-Ashry and Wanless, 1965) and Gulf co a sts of North America (McGowen and Scott, 1975; Davis et al., 1989). Sequential Analysis of Aerial Photographs The historical development of the study area was documented using maps from 1888 and aerial photographs from 1948 to 1993 in c onjunction with survey data. A sununary of the area and volume of the ebb tidal deltas and the calculated tidal prisms of Big Sarasota Pass and New Pass from 1888 to 1994 are listed in Tabl e 4. New Pass The historical map produ ce d in 1888 is the fir st known d ocu m en t at i on o f t h e

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morphology of the area. At this time New Pass had a wave-dominated morphology (Figure 24). The inlet consisted of a narrow and deep channel, approximately 6.7 m Table 4. Ebb-Tidal Delta Area, Volume and Tidal Prism from 1888 to 1987 from Davis and Gibeaut (1990), 1994 Data from this Study. New Pass Big SarasotaPass Year Area Volume Tidal Prism Area Volume Tidal Prism (m2xl06 ) (m3x106 ) (m3xl06 ) (m2xl06 ) (m3x106 ) (m3xl06 ) 1888 0.994 6.850 1948 1.006 3.226 1953 11.320 21.508 1954 5.046 14.297 1957 1.016 3.640 1969 3.700 1972 0.908 4.098 1974 1.204 4.417 1977 0.992 3.782 1982 3.364 10.367 1983 0.965 3.105 1987 4.292 22 .8 06 1994 17.8 34.9 deep. The ebb-tidal delta was small, it did not protrude from the coastline, and the seaward position of the channel had a strong southern orientation. At this time, the inlet most closely resembles its original form, i.e. before human intervention. The 1920's began the ons et of human intervention in the area. Lido Key was 55 created as John Ringling filled a group of small detached mangrove islands surrounded

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5 -. Big / , ';.bl .S, brlc Sit r; ..._ 44' :l' J.ittle Sn.rus o ,; J'L 'k cr..v:.\:t.rk.sh ,j u ll. 10 JO f,::A fi .... 0 1 : II .... .i:l.r I i 1 kilometer Figure 24. 1888 Map of Study Site showing the First Documented Morphology of New Pass and Big Sarasota Pass Depths in feet. 56

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57 by shallow seagrass beds known as the Cerol Isles (CPE, 1993b). TI1e Ringling Causeway, which connected Lido Key to the mainland, was built in 1926, and subsequently, Lido Key was gradually developed as a resort and residential village. A bridge was built over New Pass, connecting Lido Key with Longboat Key, and the charmel was dredged by the City of Sarasota (CPE, 1993b). Table 5 gives the dates, amounts, and placement of material that have been dredged from New Pass. Table 5. History of dredged quantity and placement for New Pass, from CPE (1993b). Year Source of Dredged Quantity Quantity Placed on Quantity Placed on material (m3) Lido Key (m 3 ) Longboat Key (m 3 ) 1964 New Pass 85,898 92,617 2,089 1970 Offshore* 267,857 267,857 1974 New Pass 191,327 188,343 1977 New Pass 306,101 306,101 1982 New Pass 146,939 70,408 71,303 1985 New Pass 182,908 192,908 1990/1991 New Pass 275,510 183,673 91,837 This operation was part of a federal beach erosion control project, not a New Pass charmel maintenance project. The frrst aerial photograph of the area was taken in 1948. A spit has formed on the southern tip of Longboat Key and extended inward toward Sarasota Bay (Figure 25). The growth of the spit and the dredging of the inlet sh ifted the channel between th e i s lands southward. The main ebb channel through the delta remained in a pproximat el y the same position, but the morphology of the ebb tidal delta was

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1948 A N_ 500 meters vibracore + reference point Figure 25. Morphologic Development of New Pass Ebb-Tidal Delta, 1948-1993, with Vibracore Locations 58

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59 drastically altered to a mixed-energy straight morphology (Davis and Gibeaut, 1990). This inlet morphology was caused by the dredging and by the formation of Lido Key. After Lido Key was created, tidal flow was diverted into New Pass and Big Sarasota Pass which increased tidal prisms and currents. The increased currents aided in maintaining the straight morphology of the inlet. The 1948 photograph shows the New Pass ebb-tidal delta slightly skewed to the south with approximately equal sized deposits to the north and south of the main channel. From the 1950's to the 1970's the north end of Lido Key experienced significant accretion. The north 1.2 km of the island accreted 220m (CPE, 1993b), the initiation of which are shown in the 1957 photograph (Figure 25). In 1957, the channel at New Pass has a strong southerly orientation and the ebb-tidal delta displays a mixed-energy offset morphology (Davis and Gibeaut, 1990). The northern half of the ebb tidal delta is much larger than the southern and it appears that a terminal lobe is beginning to form in the northern portion of the delta (Figure 25). The second known dredging operation occurred in 1964 when New Pass became a Federal navigational channel project. The plan called for an authorized entrance channel depth of 3.1 m (10ft), a bottom width of 31 m (100 ft) and an inner channel, which extended across Sarasota Bay to the Intracoastal Waterway, 2.4 m (8ft) deep and 31 m (100ft) wide (USACE, 1968 in CPE, 1993b) The dredging straightened the main ebb channel. In 1970, a 91 m (300 ft) terminal groin was constructed on the southern end of Longboat Key to prevent erosion caused by currents in N e w Pass (CPE, 1993b). The

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60 197 4 and 1977 photographs show little change in the north end of Lido Key, but significant progradation of the central portion of the island. The progradation was a result of placing the material dredged from the navigation channel on the beaches. In the 1974 and 1977 photographs of New Pass, the inlet exhibits a mixed-energy straight morphology (Davis and Gibeaut, 1990), but the seaward part of the channel has a renewed southward trend (Figure 25). By 1977 the straight main ebb channel split the developing terminal lobe. The reorientation of the channel is a direct result of the dredging of the inlet; the aerial photographs were taken 3 months after the completion of the dredging. The 1986 photograph of New Pass shows a well-developed delta. The main ebb channel is perpendicular to the islands The photograph also shows the well-developed swash bars that are on the swash platform (Figure 25). Also seen in the photograph is the 100 m retreat of the north tip of Lido Key and accretion of approximately 80 m for one km south (CPE, 1993b) The dredging plan for New Pass was altered in 1991 in an effort to lessen the frequent dredging. A 1,372 m (4,500 ft) section was widened by 31 m (100ft) north of the seaward dredged channel and was dredged to a depth of 3.7 m (12ft). These modifications provide extra depth for wave conditions and width for a settling basin (USACE, 1990 in CPE, 1993b). The 1993 photograph of New Pass shows the northern 1.5 km of Lido Key has experienced some minor accretion, from 30 to 70 m (CPE, 1993b) (Figure 25). The photograph also shows the channel has an extreme southerly orientation. Preparations are presently being made to dredge New Pass within the next year.

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61 Big Sarasota Pass The 1888 map shows the first documented morphology of Big Sarasota Pass; mixed-energy offset morphology (Figure 24). The inlet is approximately 425 m wide and 7 m deep. The marginal flood channels are not shown dissecting the swash platform probably because they were small and not used for navigation. The main ebb channel splits as it enters the Gulf; part of the channel heads straight into the Gulf and part bends to the south, adjacent to Siesta Key. A shallow swash platform is present off of the tip of Siesta Key. By 1942, the southern end of Lido key had eroded by 370m (CPE, 1993a). This is an indirect result of the creation of Lido Key. The increased currents and prisms of the inlets changed the cross-sections of the channels thus affecting the neighboring shorelines. The 1948 photographs of Big Sarasota Pass show numerous marginal flood channels dissecting the swash platform. The channels are adjacent to Lido Key and are concentrated in the proximal area of the ebb-tidal delta. The main ebb channel heads directly out into the Gulf with a small swash platform just the south of the main ebb channel (Figure 26). Between surveys of 1883 and 1942 the northernmost tip of Siesta Key had eroded 100m (which is probably part of the southern migration of the inlet) and the next 0.6 km accreted from 25 to 70 m. Between surveys of 1942 and 1952 the area of shoreline behind this small swash platform had accreted from 50 to 90 m (CPE, 1993a). By 1957 Big Sarasota Pass shows a significant change in the ebb-tidal delta. The main ebb challllel is deflected south upon its entrance into the Gulf by the

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1948 1957 500 meters 1974 1977 vibraco r e +refe r e n ce point Figure 26. Morphologic D eve lopment of Big Sarasota Pass Ebb-Tidal Delta, 1948-1977, with Vibracor e Locations. 62

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63 The main ebb channel is deflected south upon its entrance into the Gulf by the extension of the swash platform to the south (Figure 26). The swash platform extension is a result of increased sediment transport through creation of Lido Key, sand is no longer getting caught in the channels of the Cerol Isles. There is a dramatic volumetric increase in both of the ebb-tidal deltas, New Pass increased by 0.4x 106 m3 and Big Sarasota Pass increased by 0.8xl06 m3 from 1888 to 1954. These increases could be a result of increased flow through the deltas due to the formation of the Lido Key and the dredging of New Pass in the 1920's (CPE, 1993a). By 1969 most of the human intervention in the area that is present had been performed. During the 1960's, the flood-tidal delta of Big Sarasota Pass was filled and fmger canals were constructed, the shoreline of Siesta Key adjacent to Big Sarasota Pass had been armored, and the Intercoastal Waterway had been dredged. The 1974 photographs of Big Sarasota Pass show the southern tip of Lido Key had accreted a small amount. The main ebb channel retained its southerly orientation as it entered the Gulf (Figure 26). Also evident from the photographs is the erosion (approximately 100m) from the northern tip of Siesta Key (CPE, 1993a). During the 1970's, segments of the northern tip of Siesta Key were armored to decrease the rate of erosion. In the 1977 photographs there is a significant change in the ebb-tidal delta of Big Sarasota Pass; the swash platform midway across the delta appears to be vegetated. It is difficult to distinguish the type of vegetation, and there is no available information on whether the area was intertidal or subtidal. The area was sufficiently

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shallow and tidal currents and waves were weak enough that vegetation was established. The channel had a southerly orientation after it entered the Gulf (Figure 26). 64 In 1983, Midnight Pass, an inlet directly to the south of Big Sarasota Pass, was closed. The effects of the inlet closure were that some of the water in Little Sarasota Bay that flowed through Midnight Pass was now connected with Sarasota Bay (Davis et al., 1987). At Big Sarasota Pass, the 1983 photographs show 70 m of accretion to southern Lido Key (CPE, 1993a). The main ebb channel had a southerly orientation as it entered the Gulf. Roughly 1.5 km south of Big Sarasota Pass on Siesta Key there was an accretionary area approximately 0.5 km long (CPE, 1993a) (Figure 27). The 1993 photographs mirror the present morphology of the inlet and adjacent barrier islands. The main ebb channel of Big Sarasota Pass and the swash platform have a southerly orientation as it proceeds south into the Gulf (Figure 27). The area 1.5 km south of Big Sarasota Pass is continuing to accrete at a rate of 10 m since 1987 (CPE, 1993a). Historical summary The temporal changes in morphology have been well documented through historical aerial photographs and beach surveys. The major causes of change in New Pass and its ebb-tidal deltas have been the growth of the spit off of southern Longboat Key, dredging activity, and the formation of Lido Key. The spit has shifted the

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1983 A f).[_ vibracore 1993 +reference point Figure 27. Morphologic Development of Big Sarasota Pass Ebb-Tidal Delta, 19831993, with Vibracore Locations. channel between the islands to the south. The formation of Lido Key diverted tidal flow from small channels in the Cerol Isles to the two main inlets, Big Sarasota Pass 65 and New Pass. The increase of flow increased the tidal prisms and current velocities of both inlets. This contributed to the change of New Pass from a wave-dominated to a mixed-energy morphology. The size of the ebb-tidal deltas also increased due to the increased prisms. Sediment transport to Big Sarasota Pass may also have increased by closing of the channels in the Cerol Isles. The dredging activity at New Pass has maintained a large channel and increased tidal flow changing the wave-dominated ebbtidal delta to a mixed-energy morphology (Davis and Gibeaut, 1990). The dredging

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66 has also decreased the migration of the pass and the natural sand bypassing that was prevalent in the late 19th and early 20th century is almost nonexistent today. In the last 20 years maintenance dredging has been the principal means of bypassing. The morphology of the New Pass repeatedly shifts from mixed-energy straight (1948, 1974, 1977, 1983) to mixed-energy offset (1957, 1969, 1972). The channel and ebb tidal delta have a history of migrating to the south in response to the net southerly drift entering the system from Longboat Key and becomes reoriented by the dredging activity. The ebb-tidal delta is fairly effective in shielding the northern end of Lido Key from wave attack and subsequent erosion shown in the shoreline south of the inlet which has advanced 200 meters from 1883 to 1992 (CPE, 1993b). Big Sarasota Pass has been classified as having a mixed-energy offset throughout recorded historical times. But there has been a change in the orientation of the main ebb channel from entering the Gulf in a straight orientation during the period from 1888 to 1948 to a southerly orientation from the 1950's to the present. The straight orientation of the channel allowed development of a swash platform off the northern tip of Siesta Key and accretion of the shoreline behind the platform. With the main ebb channel shifted to a southerly orientation as it enters the Gulf of Mexico, there is no swash platform directly adjacent to Siesta Key protecting the shoreline from erosion. There is erosion at the tip of Siesta Key and the area of accretion has shifted south 1.5 km. One to 3.5 km further south, the beach has been accreting since 1883. The greatest accretion, 275 to 400 m, occurred from 2.5 to 3.5 km south of the inlet.

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67 Big Sarasota Pass has a history of migrating southward. Between 1883 and 1942, the inlet migrated approximately 240 m south. With hardening of the Siesta Key shoreline the rate of southerly migrated has diminished; from 1942 to 1987 the shoreline has prograded 12 m to the north. This progradation appears to have been concentrated between the years of 1952 to 1971. The marginal flood channels of Big Sarasota Pass migrated across the ebb-tidal delta through time. Generally the marginal flood channel that is adjacent to Lido Key is the widest, deepest, and has the strongest currents in comparison to the shallower marginal flood channels. The very southern tip of Lido Key has retreated 360m from 1883 and 1942 due to change in the channel's cross section in response to the increased tidal prism. From the 1940's to the present the shoreline has experienced fluctuating erosion and accretion. At present the shoreline has accreted 200m since 1942. The southern end of Lido Key is very unstable with significant erosion and accretion occurring between times documented by the photographs

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68 STRATIGRAPHY Vibracores, core borings collected by the U.S. Army, Corps of Engineers, and seismic data were collected in order to describe and interpret the stratigraphy and geologic history of the ebb-tidal deltas of Big Sarasota Pass and New Pass. Interpretations of the depositional environments seen in cores are based on comparison of sediment composition and texture with surface samples from modern ebb-tidal delta environments and on bedforms observed on the ebb-tidal deltas and channels. The twenty-four vibracores collected provide detail of the internal stratification of the ebb tidal delta. The core borings taken by the U.S. Army, Corps of Engineers (Figure 10) penetrate the modern ebb-tidal delta and underlying sediments thus providing information on sediment body thickness and geometry. The seismic data collected (Figure 12) provide detail on the internal structure and geometry of the unconsolidated deposits and bedrock. Facies have been identified and used to construct a geologic history of the two ebb-tidal deltas. Lithofacies Through examination of the vibracores and the core borings three lithofacies were distinguished within the unconsolidated sediments at Big Sarasota Pass and New Pass ebb-tidal deltas. The lithofacies were defmed on the basis of composition

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69 (percentages of gravel, sand, mud) and on sedimentary structures (including planar and cross-stratification, and bioturbation). The interfmgering quartz sand facies and shelly facies overlie the muddy sand facies. Comparison with work by others along this same barrier coast (Brame, 1976; Cuffe, 1991) also aided in interpreting depositional envirorunents of similarly described facies. Quartz sand facies Description The quartz sand facies consists of clean, fme-grained, quartz sand (2.5 to 2.8 ). There is a very small shell component in this facies in the form of sandand gravel-sized pieces, generally consisting ofless than 5% carbonate, but sometimes as high as 10%. The carbonate fraction often delineates laminations that otherwise would not be seen due to the sediment homogeneity. Mud is rare due to reworking and removal by wave energy (Cuffe, 1991). Mud can be found as flasers and outlines of burrows, which are rare, but were found at depth in some cores (BSP-10, BSP-14). This facies varies in thickness and can be as thick as 2.54 m (NP-2, NP 8, BSP-6). A distinctive faunal assemblage is represented by the shell material incorporated in this unit with the most abundant taxa being Lucina floridiana, Donax variables, and Tellina sp .. Interpretation The sand facies occurs around the margins of the ebb-tidal delta, which are the wave-dominated areas, mainly the swash platform and terminal lobes. Although

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70 internal stratification is poorly defmed in these deposits due to sediment homogeneity. there is some planar-horizontal stratification present. The faunal assemblage is composed of species that live in the Gulf. thus the shells were either transported by waves or live on the ebb-tidal delta There are back barrier species scattered throughout the deposit. The flasers are composed of mud pellets suggesting a biogenic origin. It is difficult to map the thickness variation of this facies across the delta due to limited vibracore lengths. It is thickest in areas of the swash platforms that are away from the marginal flood channels; in distal portions of the ebb-tidal delta. Shelly facies Description This facies is characterized by the presence of shell beds of different thicknesses and composition. Two main types of shell beds have been distinguished. The type 1 shell beds are laminated. generally <25 em thick and are composed of <25% gravel which is moderateto well-sorted fragmented shells (Figure 28). There are rarely shells larger than -2.5 . From the few identifiable shells present an assemblage has been constructed which in order of decreasing abundance consists of Donax variablis. Lucina jloridiana. Chione cancellata. and Tellina sp .. Type 2 shell beds are laminated and generally thicker than type 1 shell beds. They range from 10 em to 108 em thick, but are generally >25 em. The shell beds are dominated by gravel-sized whole shells that generally comprise >25% of the sediment and are typically poorly-sorted (Figure 28). All of the beds sampled had

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B) t OJ, li! (J) -o Figure 28. Photographs of She ll Beds: (A) Type 1 She ll Bed in Vibraeore BSP-14 from 150 em to 180 em, (B) Type 2 Shell Bed in Vibracore BSP-7 from 180 em to 230 em.

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shells larger than -3 . A distinctive assemblage of faunal types includes Chione cancellata, Anadara transversa, Tellina sp., and Donax variablis. 72 Interpretation The shelly facies is most abundant and thickest in the proximal areas of the ebb-tidal deltas, which are areas that have been historically dominated by marginal flood channels. The facies also occurs on the swash platform scattered in areas near the main ebb channel. At New Pass the marginal flood channels produce shelly facies in small areas on both sides of the main ebb channel while at Big Sarasota Pass the facies is found in one broad area on the north side of the main ebb channel. Due to the ample supply of whole and fragmented shells, the two different types of shell beds probably are a product of two different flow regimes. Type 1 shell beds are produced by weaker currents than those that produced type 2 shell beds. Cores exhibiting thick sequences of type 2 shell beds, (BSP -9, NP-5, NP-7, NP-9) are found in areas that have historically been dominated by stable marginal flood channels. These channels are deeper and have stronger tidal currents than the ephemeral marginal flood channels that have a history of migrating across the swash platform Cores that were taken in areas dominated by migrating marginal flood channels (BSP-1, BSP 2, BSP-7, BSP-13, BSP-14) show thin sequences of type 1 and 2 shell beds. The type 1 shell beds are also formed in areas where velocities in the marginal flood channels are not as high or the channel is on the edge of the swash platform (BSP-8, BSP-10, NP -4, NP-8) This is an environment where the tidal currents are weaker in comparison to areas that are adjacent to the main ebb chann el. Type 1 and 2 shell beds

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73 are also found in areas adjacent to the main ebb channel which have been sampled by the cores BSP-5, BSP-6, NP-3. In both types of shell beds the faunal assemblage is dominated by open-marine species suggesting transport from offshore and nearshore. The scattered presence of Terebra sp. and Ostrea sp. indicates some transport of shells from back-barrier environments. These back-barrier species are not concentrated in any area within the ebb-tidal deltas. Muddy Sand Facies Description There is a unconsolidated sedimentary unit beneath the modem ebb-tidal delta and overlying bedrock Core logs complied by the U.S. Army, Corp of Engineers provide information on thickness and limited grain size data of units which lay beneath the modem ebb-tidal delta. The mud content of the unit varies from 7 to 26% and the gravel portion, which is 100% CaC03 ranges from 0 to 30%. The facies is thin (0.9 m) to absent in the distal areas of the ebb-tidal delta and reaches 3.6 m in thickness near the main ebb channel beneath the swash platform. The faunal assemblage incorporated in this unit is dominated by Lucina floridiana, Chione cancellata, Anadara transversa, and Anomia sp .. Interpretation The modem ebb tidal delta overlies a massive, grey to dark grey muddy sand unit. It is difficult to interpret the depositional environment of this facies due to

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74 lack of recognition of structures and limited grain-size data, however, the muddy sand facies found at this site is similar to the muddy sand facies delineated by Cuffe (1991) at the Hurricane Pass ebb-tidal delta. The muddy sand facies at Hurricane Pass was interpreted as a shallow-shelf, low-energy deposit. Tills interpretation was based on the faunal assemblage and a comparison of the placement of the cores to the development of the ebb-tidal delta which was carefully documented through use of aerial photographs. The lack of accurate data on this facies in this study and the development of the ebb-tidal deltas makes it nearly impossible to interpret the depositional envirorunent of this facies. Modem EbbTidal Deltas The ebb-tidal deltas are dominated by sand and shells, and lack significant amounts of mud. The quartz sand facies consists of fme-grained quartz sand that is massive to slightly stratified with planar-horizontal stratification. The facies is formed in wave-dominated areas, swash platform and terminal lobe, which are located around the edges of the ebb-tidal deltas. The shelly facies consists of laminated shell beds which are formed in the marginal flood channels and in the main ebb channels. The facies is formed in tide-dominated areas, in the center and in the proximal areas of the ebb-tidal deltas. The full thickness (6.4 m) of the ebb-tidal delta deposits was only observed at Big Sarasota Pass through use of the USACE core borings (Figure 29). The ebb-tidal delta is thickest in the area where the main ebb channel exits into the

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Big Sarasota Pass Siesta Ke y 500 meters + 0 0-3 m 03-5m 0>5m vibracores + USACE Figure 29. Map of Big Sarasota Pass with Thickness of the Modern Ebb Tidal Delta in Meters 75

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76 Gulf. The cross-sections clearly show the organization of the quartz sand and shelly facies The shelly facies thins distally (Figure 30 and 31) and away from the center of the ebb-tidal delta (Figure 32 and 33). The quartz sand facies is thickest on the edges and in the distal areas of the ebb-tidal deltas. Bedrock Topography There are three distinct lithic units near the surface in the Sarasota Bay area; the Bone Valley Member (Middle and Upper Miocene) of the Hawthorn Group, the Caloosahatchee (early to middle Pleistocene), and the Ft. Thompson (Late Pleistocene) (Cook. 1945; DuBar, 1974) Limestone outcrops on the southwest shore of Sarasota Bay are light-yellow, quartzose, and contains some marine mollusks which corresponds to descriptions of other Hawthorn Group outcrops (Cooke, 1945; Knowles, 1983) The Caloosahatchee Formation is composed of shelly, calcareous, fme sands calcarenites, and limestones (DuBar, 1974). The Ft. Thompson Formation consists of alternating fresh-water, brackish-water, and marine marls and limestones. Along the west coast of Aorida, the formation is represented by marginal-marine and brackish water shelly sands and calcareous, unfossiliferous sands, as well as sands that contain fresh-water and terrestrial vertebrate fossils (DuBar, 1974). The molluscan beach rock exposed at Point of Rocks, in the middle of Siesta Key (Figure 34), has been considered to be equivalent to the Late Pleistocene Anastasia Formation of the east coast of Aorida. Samples observed with enclosed bullet casings suggest a Holocene age (Knowles, 1983)

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North South 1 1' ____ B _S P _-1_ 3 ______ B S _P-_ 2 __________ B _SP_ 3 ___________ B _S_P-_4 _______ BS_P_-6 __ 0 marginal flood channel 0.5 1 swash platform 1.5 2 kilometers 1 (f) Q) ..... Q) E 2 3 2 5 A N_ 1km D quartz sand facies C] shelly facies Figure 30. Cross-section 1-1' across the EbbTidal Delta of Big Sarasota Pass from Lido Key to the Gulf of This cross-section shows the thickness of the shelly facies pinching out into the swash platform.

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Southwest 2 NP-6 NP-2 NP-5 2' .----------------------------r-0 MLW swash platform 1 2 .. l . ) 3 . ,,.....__,. '"'-' 0 0.5 1 1.5 kilometers 2 D quartz sand facies EJ shelly facies Figure 31. Cross-section 2-2' across the EbbTidal Delta of New Pass, from Longboat Key to the Gulf of Mexico.

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("() 0\ 0\ ,......; ..... r.IJ rc ..... r.IJ Q) ("() ("() .....J 0 !:'-.. p., Cfl c:l N p., Cfl c:l 00 p., Cfl c:l E ... 0 ..... -. 1-< _. u .! ro _. ::l V' til D [] Sli3li3Ul "'I I "'I II ' "'I 1: N .',. -c:f') ....-< r.IJ 1-< Q) ..... Q) li1S oo ........ ;Q . . . . . . . . . . . 0 r.IJ 0 ....c: r.IJ t:: 0 -..... u Q) r.IJ Q) ....c: E-< rc: ..... CiJ 0 "@ "d I ,..D 79 ,..D r.IJ c r.IJ c c;l rc: P-<,..r:: c;l u ..... ,..D o...o Q) 1-< c cl$ bOS i:i5 Q) O.i....C: ....c: ..... ..... s ...... 0 0 1-< C"C"-< Q) >.. rc "@ ro s ...-1 ....-! >< u 0 rc: !-1 ...... Q),_.., ....c: Q) ..... ,...c: r.IJ r.IJ r.IJ Q) O,..r:: ..... u..._. ro o 0'5 ("() 0 c bO 0 c z ....... u....c: Q) u r.IJ c I -0.. 0 Q) u ..... ('.1 ("() Q) !-1 ::l bO -J:..I..

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4 NP-4 NP-5 4' NP-8 0 --:,:--.:..--... rv C'.J ;.v . "Y. swash platform kilometers 0.5 main ebb channel 1 2 3 4 Figure 33. Cross-section 4-4' across the Proximal Area of the New Pass EbbTidal Delta. D quartz sand fac ies E3 shelly facies 00 0

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I I \ 1\ ' Phillippi Creek km Figure 34 Map of Bedrock Topography of Sarasota Bay and Surrounding Areas, modified from .Knowles (1983). The contour interval is 2 meters and the datum is mean sea-level. 81

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82 The bedrock surface in Sarasota Bay has been mapped by Knowles (1983) using vibracores and other data. The Ft. Thompson Formation and the Hawthorn Group were found in the bottom of some of the vibracores collected by Knowles (1983) The bedrock is gently sloping in the gulfward direction; beneath Sarasota Bay the bedrock slopes approximately 2 m/km or less (Figure 34) Just south of Sarasota Bay, specifically northern Siesta Key, the bedrock surface is steeply dipping toward the Gulf; the slope is about 3.2 m/km or greater. Longboat, Lido, and Siesta Keys have apparently stabilized along a zone about 8 m above the bedrock (Knowles, 1983). There are small-scale variations in the bedrock topography between cores (0.25 m difference in elevation), but these variations are often too small to be distinguished in seismic section. There are no significant changes in the bedrock topography in the area surrounding Big Sarasota Pass (Figure 35 and 36). Just to the south of Big Sarasota Pass there is a linear depression in the surface of the bedrock which coincides with the position of Phillippi Creek (Figure 34). The depression is very localized; it does not appear in the offshore area The bedrock in the vicinity of New Pass appears to have a strange pattern. The bedrock topography along Lido Key is gently sloping offshore. The bedrock appears to be much deeper offshore of the south end of Longboat Key. Above the bedrock the sediment package is dominated by complex cut and fill structures (Figure 37 and 38), thus the bedrock may have been eroded by the action of a tidal inlet or a coastal stream. The bedrock is represented by many reflectors, in the seismic sections,

PAGE 95

Southwest Northeast Lido Key Gulf of Mexico A) C' 25 0.0 B) C' 0 Ui' g 5 Qj Qj 10 :> ra l:l ;:.., 15 ra I 0 20 f-. 25 0.0 0.5 0.5 1.0 ebb-tidal delta sediments 1.5 Distance (km) ro rading foresets 1.0 1.5 Distance (km) ..... 2.0 2.5 erosional surface USACE y 2 0 2.5 Figure 35. Seismic Line C: (A) Analog Print, (B) Interpreted Section. The section is north of Big Sarasota Pass showing the location of USACE core and prograding forsets. c 0 5 10 15 c 0 5 10 15 -til ... Qj ..... Qj g -5 0.. Qj "'0 Qj ..... ra )( 0 ... 0.. 0.. Ui' ... Ql ..... Ql g ii 0.. Ql "'0 Ql ..... ra s x 0 ... 0.. 0.. 00 UJ

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North A) D (j) g Qj > !1l .l:l >. !1l I 0 1B) 0 5 10 15 20 25 30 35 0 0 D 0 0.5 1.0 Distanc e (km) 1.5 2.0 So u t h D 0 ,....._ 5 +------------------------------------------------------------------------------------------+-0 "' g 10 cu 15 Qj approximate edges of ebb-tidal delta > !1l .l:l 20 >. !1l 6 135 0.0 0.5 1. 0 Distance (km) 1.5 2.0 Figure 36. Seismic Line D: (A) Analog Print, (B) Interpreted Section. The section shows the seaward e d ge of the ebb-tidal delta at Big Sarasota Pass and karstic bedrock.

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Gulf of Mexico Southwest 5 30 35 0.0 B) A 0 0.5 1.0 Distance (km) 1.5 85 Longboat Key 2.0 A' 5 t--------------------------------------Lo erosional surface 30 35 0.0 0.5 1.0 Distance (km) complex cut and fill structure 1.5 2.0 20 Figure 37. Seismic Line A: (A) Analog Print, (B) Interpreted Section. The section is north of New Pass showing complex cut and fill structures, erosional surface and dissolutional features.

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86 North Longboat Key South Gulf of Mexico A) B Bl 0-,.---------------. 30 0.0 0.5 1.0 Distance (km) T 1.5 2.0 B) B B' QJ : Qj ;;.. ro .b >. ro 0 f--< 0 15 20 25 1.0 Distance (km) 1.5 2.0 0.0 0.5 Figure 38. Seismic Line B: (A) Analog Print, (B) Interpreted Section. The section shows the complex cut and fill structures and erosional surface along New Pass ebb-tidal delta. = 0.. QJ 10 ro E ;:;: 0 .... 15 : <

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87 displaying its irregularity. The gently warping depressions in the bedrock are believed to be sinkholes caused by dissolution of the limestone at depth. Although the bedrock is very irregular it is truncated by a virtually planar erosional surface (Figure 35, 36, 37, and 38) The position and morphology of the ebb-tidal deltas is not believed to be affected by the irregular bedrock topography.

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88 GEOLOGIC HISTORY OF NEW PASS AND BIG SARASOTA PASS A great deal of study on sea-level and geologic history of the west-central Florida coast has been conducted by previous researchers. Many of these studies are stratigraphic facies analysis in Pinellas County (Brame, 1976; Kuhn, 1983; Evans et al 1985; Cuffe, 1991 ; Gibbs, 1991), Sarasota Bay (Knowles, 1983), and Little Sarasota Bay (Bland, 1985) In order to interpret the geologic history of the study site, the sea-level model developed by Scholl and Stuvier (1967) will be utilized (Figure 4). Approximately 4,000-6,000 years ago the rate of sea-level rise decreased after which barrier islands started to form (Otvos, 1970). The first barrier islands of west central Florida formed at this time in Pinellas and Pasco Counties, about 80 km north of Sarasota Bay (Brame, 1976; Kuhn, 1983). Barrier islands enclosing Sarasota Bay are also believed to have formed at this time (Knowles, 1983). In Little Sarasota Bay, just to the south of the study site, oyster reefs directly above bedrock date to 5,000 years ago, suggesting that the Holocene transgression began to inundate the bedrock surface about this time (Shock, pers comm.). Sea-level at this time was approximately 4 m below its present position (Scholl and Stuvier, 1967). Even though sea level has been rising, the barrier islands may not have migrated a great distance since their formation; Knowles (1983) found barrier island deposits formed 5.7 m below the south end of Longboat Key. These deposits may be the earliest evidence for barrier islands The fairly rapid rise of sea-level at this time, 30 cm/100 years (Scholl and Stuvier,

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89 1967), may have destroyed or covered other barrier island deposits. By 3,500 years ago sea-level was approximately 1.6 m below present sea-level and the rate of sea-level rise had slowed to 6 cm/100 yrs (Scholl and Stuvier, 1967). This is a period when the oldest dated barrier island deposits near the study site were formed. The beach ridges at central Siesta Key were formed 2,000-3,000 years ago and have been grouped into a time-stratigraphic unit called Sanibel I (Figure 39 and 40). At approximately the same time, 2,270 years ago, a hurricane opened an inlet at New Pass (Figure 40), depositing a storm unit (Knowles, 1983). The storm unit is overlain by protected bay sedimentation and thus New Pass is believed to have closed shortly thereafter (Knowles, 1983). The next set of beach ridges, the Wulfert set, accumulated from 1,500 to 2,000 years ago (Figure 39). The set is interpreted by Stapor et al. (1988, 1991) to have formed 4 meters above present mean sea-level but sea-level is believed to be just over a meter below present mean sea-level. Thus the period was a time of increased wave and storm activity. At approximately the same time, 1,320 years ago, an inlet was opened at New Pass by a hurricane (Knowles, 1983). Knowles (1983) believes that New Pass was closed by littoral drift along the Gulf shoreline. The undated set of beach ridges on northeast Siesta Key (Figure 39) is believed to have formed as part of Sanibel I or the Wulfert sets on Siesta Key and was temporarily separated from the rest of Siesta Key by erosive action. The northeast set appears to have been created during two different situations. The parallel north-south oriented set appears to be truncated by a single northeast ridge. The orientation of the single ridge suggests it was formed on an inlet margin.

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\ \ ) "' (--7 SIESTA KEY SARASOTA CO. FLORIDA ROBERTS BAY N GULF OF MEXICO BEACH AND DUNE BEACH RIDGES D MARSH D PRE-HOLOCENE MAINLAND 1 SAMPLING SITES SANIBEL II (500 -7 YR. BPI LA COSTA (1000 -500 YR. BPI WULFERT (2000 1500 YR. BPI (:: ::;:j SANIBEL I (3000 2000 YR. BPI ....... ....... ..:::::::: ... .PHILLIPPI CK . :. :. :. :. :-:-:-: ............. ..... ...... . :::-:::::::: 90 Figure 39 Map of Northen Siesta Key with Beach-Ridge Sets Mapped from 1948 Aerial Photographs, from Stapor et al. (1988).

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2,000 yrs B.P. 1,300 yrs B.P. 1,000 years B.P. Figure 40. Geologic Reconstruction of the Study Site from 3,000 Yrs. B.P to 1,000 Yrs. B.P. 91

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92 Since the creation of barrier islands at the study site, which may be from 3,000 to 6,000 years ago, there has been an inlet serving the tidal flux of south Sarasota Bay. The inlet probably shifted in position through time between Siesta Key and Longboat Key, often occupying the position of New Pass, documented by storm deposits associated with an inlet. By the end of the Wulfert period, the inlet had migrated to the south, truncating the north-south set of undated beach ridges and forming the single northeast ridge. The break between the undated beach ridge set and the Sanibel I and Wulfert sets was probably caused by erosion. Erosive action could be a combination of two factors, including erosive wave action shifting the shoreline to the east and a break in the barrier islands which facilitated the erosion of sediment. If a breach of the islands was involved, Phillippi Creek may have played a role as seen by its proximity to the northern edge of the Sanibel I set. It is also unlikely that an inlet serving south Sarasota Bay, positioned between Siesta Key and Longboat Key, would have shifted its position around the undated beach ridge set without destroying it. The La Costa set of beach ridges, which formed 500 to 1,000 years ago, has filled in the breach of Siesta Key (Figure 39 and 40). The beach ridges were formed by northward-directed littoral drift in conjunction with direct onshore movement of sand (Stapor et al., 1988, 1991). The La Costa set shows no influence of an inlet or ebb-tidal delta therefore the inlet is approximated to have been a minimum of 2 kilometers north of its present position. Beach ridge sets seaward of the La Costa group have not been dated but have

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93 been tentatively placed in the infonnal time-stratigraphic unit Sanibel II (less than 500 BP) (Figure 39 and 41). The beach ridge's convex-seaward geometry suggests that the inlet, Big Sarasota Pass, and ebb-tidal delta were supplying sediment to the developing beach ridge sets and protecting the shoreline from erosive wave action. The first beach ridges of the set were formed when Big Sarasota Pass was north of its present position by not more than 0.75 km. The thick units of the shelly facies beneath the present marginal flood channels document the northern portion of the main ebb channel (Figure 32). Through time, Big Sarasota Pass migrated to the south, eroding the north part of the beach ridges on Siesta Key. The southerly migration also shifted the zone of accretion on Siesta Key to the south. The 1948 photograph of Big Sarasota Pass exhibits the localized accretional area on the north tip of the island (Figure 26). The inlet had a straight orientation into the Gulf of Mexico with a small swash platform developed off the north tip of Siesta Key. Directly behind the platform, the north tip of Siesta Key is accreting. During this period, the inlet was very effective in transporting sediment to the ridges, and there was an increased sediment supply demonstrated by the widely spaced ridges (Stapor et al., 1988). This is the period when Big Sarasota Pass began developing its present mixed-energy offset morphology.

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5 kilometers 500 yrs B.P. Present Figure 41. Geologic Reconstruction of the Study Site from 500 Yrs. B.P. to the Present. 94

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CONCLUSIONS An inlet or inlets has migrated between Siesta Key and Longboat Key since the formation of the barrier islands which is from 3,000 to 5,000 years ago. 95 Big Sarasota Pass has been in the approximate same position and initiation of the offset morphology began during the past 500 years. New Pass was formed in 1848 by a hurricane breaching southern Longboat Key. 1hrough historical times the morphology of New Pass was changed from wave dominated to tide-dominated by the dredging activity and the fonnation of Lido Key. The main ebb channel of Big Sarasota Pass had a straight orientation from 1888 to 1948, and then an increase in sediment input caused by the formation of Lido Key resulted in the southerly orientation of the channel from the 1950's to the present. The change in morphology has caused the channel to erode the north tip of Siesta Key and shifted the area of accretion 1.5 kilometers to th e south of Big Sarasota Pass. The tidal prism of the flood-dominated Big Sarasota Pass has historically been

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approximately one order of magnitude higher than that of the ebb-dominated New Pass. 96 A portion of the water that is flooding through the Big Sarasota Pass is ebbing through New Pass, explaining the flood-dominance of Big Sarasota Pass and the ebb-dominance of New Pass. The modem ebb-tidal delta is composed of two facies; the sandy facies, which is produced in wave dominated areas, and the shelly facies produced in tide dominated areas. The stratigraphy of the New Pass and Big Sarasota Pass ebb-tidal deltas are different because the morphologies of the inlets are different. The symmetrical New Pass ebb-tidal delta produces the quartz sand facies and the shelly facies on both sides of the inlet while the asymmetrical Big Sarasota Pass ebb-tidal delta produces the modem ebb-tidal facies only on the north side of the main ebb channel.

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REFERENCES Allen, G.P., (1971). Relationship between grain size parameters distribution and current patterns in the Gironde Estuary (France). Journal of Sedimentary Petrology, 41, 74-88. Allen, J.R.L., (19?4): Reaction, relaxation, and lag in natural sedimentary systems: general pnnctples, examples, and lessons. Earth Science Reviews 10 263342. _, Boothroyd, J.C., (1985). Tidal inlets and tidal deltas, in Davis, R.A., Jr., ed., Coastal Sedimentary Environments, New York, Springer-Verlag, p. 444-525. 97 Boothroyd, J.C., and Hubbard, O.K., (1975). Genesis of bedforms in mesotidal estuaries, in Cronin, L.E., ed., Estuarine Research, v. 2, New York, Academic Press, p. 217-234. Bland, M.J., (1985). Holocene geologic history of Little Sarasota Bay, Florida. UnPubl. M.S. thesis, University of South Florida, 101 p. Brame, J. W ., ( 197 6). The stratigraphic and geologic history of Caladesi Island, Pinellas County, Florida, Unpubl. M.S. Thesis, University of South Florida, 109 p. Brand, S., (1990). Tampa Bay as a hurricane haven. NOAA Mariner's Weather Log, v. 34, no.1, p. 48-51. Bruun, P.F., and Gerritsen, F., (1959). Natural by-passing of sand at coastal inlets. Journal of Waterways and Harbors Division, 85, 75-107. Byrne, R.J., Bullock, P., and Tyler, D.G., (1975). Response characteristics of a tidal inlet: A case study, in Cronin, L.E., ed., Estuarine Research, v. 2, New York, Academic Press, p. 201-216. Cooke, C.W., (1945). Geology of Florida. Florida Geological Survey, Bull. 29, 342 p. Coastal Planning & Engineering, (1993a). Big Sarasota Pass inlet management plan. Submitted to the City of Sarasota. 130 p. Coastal Planning & Engineering, (1993b). New Pass inlet management plan. Submitted to the City of Sarasota. 143 p.

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Coastal Planning & Engineering, (1993c). Wave refraction and sediment transport study of New Pass and Big Sarasota Pass, Sarasota County, Florida. 43 pg. Cuffe, C.K., (1991). Development and stratigraphy of ebband flood-tidal deltas at Hurricane Pass, Pinellas County, Florida. Unpubl. M.S. thesis, University of South Florida, 17 4 p. Davis, R.A., Jr, (1989). Morphodynamics of the west-central Florida barrier system: the delicate balance between waveand tide-domination. In Proceedings Symposium "Coastal Lowlands, Geology and Geotechnology", Kluwer, Dordrecht, p. 225-235. 98 Davis, R.A., Jr., and Fox, W.T., (1981). Interaction between waveand tide-generated processes at the mouth of a microtidal estuary: Matanzas River, Florida (U.S.A.). Marine Geology, 40, 49-68. Davis, R.A., Jr., Hine, A.C., and Belknap, D.F., (1982). Coastal zone atlas: northern Pinellas County, Florida: Final report to Florida Sea Grant Program, Project R/OE-17, 37 p. Davis, R.A., Jr., and Hayes, M.O., (1984). What is a wave-dominated coast? Marine Geology, 60, 313-329. Davis, R.A., Jr., and Kuhn, B.J., (1985). Origin and development of Anclote Key, west-peninsular Florida. Marine Geology, 60, 313-329. Davis, R.A., Jr., Hine, A.C., and Bland, M.J., (1987). Midnight Pass, Florida: Inlet instability due to man-related activities in Little Sarasota Bay. In Coastal Sediments '87, ASCE, (pp. 2062-2077). Davis, R.A., Jr., and Gibeaut, J.C., (1990). Historical morphodynamics of inlets in Florida: models for coastal zone planning. Sea Grant Project No. R/C-S-23, Technical paper 55, 81 p. Dubar, J.R., (1974). Summary of the Neogene stratigraphy of southern Florida, in Oaks, R.Q., Jr. and DuBar, J.R., eds., Post-Miocene Stratigraphy Central and Southern Atlantic Coastal Plain, Utah State University Press, Logan, Utah, p. 206-232. El-Ashry, M.T., and Wanless, H.R., (1965). Birth and early growth of a tidal delta. Journal of Geology, 73, 404-406. Evans, M.W., Hine, A.C., Belknap, D.F., and Davis, R.A., Jr., (1985). Bedrock controls on barrier island development: West-central Florida coast. Marine Geology, 63, 263-283.

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99 Finley, R.J., (1975). Hydrodynamics and tidal deltas of North Inlet, South Carolina, in Cronin, L.E., ed., Estuarine Research. v. 2, Academic Press, New York, p. 277-291. Finley, R.J ., (1978). Ebb-tidal delta morphology and sediment supply in relation to seasonal wave energy flux, North Inlet, South Carolina. Journal of Sedimentary Petrology, 48, 227-238. FitzGerald, D.M., (1976) Ebb-tidal delta of Price Inlet, South Carolina: geomorphology, physical processes and associated inlet shoreline changes, in Hayes, M.O. and Kana, T.W., eds., Terrigeneous Clastic Depositional Environments. Tech. Rept. No. 11-CRD, University of South Carolina, p. II143 II-157. FitzGerald, D M., (1984). Interactions between the ebb-tidal delta and landward shoreline: Price Inlet, South Carolina. Journal of Sedimentary Petrology, 54, 1303-1318. FitzGerald, D.M., and Nummedal, D., (1983). Response characteristics of an ebb dominated tidal inlet channel. Journal of Sedimentary Petrology, 53, 833845. Gibbs, A.E., (1991). Stratigraphy and geologic history of Three Rooker Bar: a recently emergent barrier island on the west-central coast of Florida. Unpubl. M.S Thesis, University of South Florida, 132 p. Gibeaut, J.C., and Davis, R.A., Jr., (1993). Statistical geomorphic classification of ebb tidal deltas along the west-central Florida coast. Journal of Coastal Research, Special Issue #18, p. 165-184. Harvey, J., (1982). "An assessment of beach erosion and outline of management alternatives; Longboat Key, Florida." Hayes, M O., (1975). Morphology of sand accumulations in estuaries, in Cronin, L .E. ed., Estuarine Research, v. 2, Academic Press, New York, p. 3-22. Hayes, M.O., (1979). Barrier island morphology of a function of tidal and wave regime, in Leatherman, S.P., ed., Barrier Islands. from the Gulf of St. Lawrence to the Gulf of Mexico, Academic Press, New York, p. 1-27. Hayes, M.O., Goldsmith, V., and Hobbs, C H., (1970). Offset coastal inlets. In Proceedings of 12th Coastal Engineering Conference, ASCE, p. 1187 1200. Hayes, M.O., and Kana, T.W., (1976). Terrigeneous clastic depositional environments. Tech. Rept. No. 11-CRD. University of South Carolina. 315 p.

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100 Hine, A.C., (1975). Bedform distribution and migration patterns on tidal deltas in the Chatham Harbor Estuary, Cape Cod, Mass., in Cronin, L.E. ed., Estuarine Research, v. 2, Academic Press, New York, p. 235-252. Hubbard, D.K., Oertel, G., and Nummedal, D., (1979). The role of waves and tidal currents in the development of tidal-inlet sedimentary structures and sand body geometry: examples from North Carolina, South Carolina and Georgia. Journal of Sedimentary Petrology, 49, 1073-1092. Hubertz, J., and Brooks, R., (1989). Gulf of Mexico hindcast wave information, WIS Report 18, U.S. Army Waterways Experiment Station. Imperato, D.P., Sexton, W.J., and Hayes, M.O., (1988). Stratigraphy and sediment characteristics of a mesotidal ebb-tidal delta, North Edisto Inlet, South Carolina. Journal of Sedimentary Petrology, 58, 950-958. Jarrett, J.T., (1976). Tidal prism-inlet area relationships. G.I.T.I. Rept. No. 3, U.S. Army, Corps of Engineers, Coastal Engineering Research Center, Vicksburg, MS, 55 p. Knowles, S.C., (1983). Holocene Geologic History of Sarasota Bay, Florida. Unpubl. M.S. thesis, University of South Florida, 128 p. Kuhn, B.J., (1983). Geology and Holocene history of Anclote Key, Pinellas County, Florida. Unpubl. M.S. thesis, University of South Florida, 108 p. Lanesky, D.E., Logan, B.W., Brown, R.G., and Hine, A.C., (1979). A new approach to portable vibracoring underwater and on land. Journal of Sedimentary Petrology, 49, 54-57. Ludlum, D.M., (1963). Early American hurricanes, Am. Meteorological Soc., Boston Mass., 198 p. Lynch-Blosse, M.A., and Kumar, N., (1976). Evolution of downdrift-offset tidal inlets: a model based on the Brigantine inlet system of New Jersey. Journal of Geology, 84, 165-178. McGowen, J.H., and Scott, A.J., (1975). Hurricanes as geologic agents on the Texas coast, in Cronin, L.E. ed., Estuarine Research, v. 2, Academic Press, New York, p. 23-46. Oertel, G.F., (1972). Sediment transport on estuary entrance shoals and the formation of swash platforms. Journal of Sedimentary Petrology, 42, 857-863.

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Oertel, G.F., (1975). Ebb-tidal deltas of Georgia estuaries, in Cronin, L.E. ed., Estuarine Research, v. 2, Academic Press, New York, p. 267-276. Oertel, G.F., (1977). Geomorphic cycles in ebb deltas and related patterns of shore erosion and accretion. Journal of Sedimentary Petrology, fl. 1121-1131. 101 Otvos, E.G., Jr., (1970). Development and migration of barrier islands, northern Gulf of Mexico. Geological Society of America Bulletin, 81, 241-246. Price, W.A., (1963). Patterns of flow and channeling in tidal inlets. Journal of Sedimentary Petrology, 33, 279-290. Sha, L.P., (1989). Variation in ebb-delta morphologies along the West and East Frisian island, the Netherlands and Germany. Marine Geology, 89, 11-28. Sha, L.P., and de Boer, P.L., (1990). Ebb-tidal delta deposits along the west Frisian Island (The Netherlands): processes, facies architecture and preservation, in Smith, D.G., Reinson, G.E., Zaitlin, B.A., and Rahmani, R.A., eds., Clastic Tidal Sedimentology: Canadian Society of Petroleum Geologists, Memoir 16, p. 199-218. Scholl, D.W., and Stuvier, M., (1967). Recent submergence of southern Florida: A comparison with adjacent coasts and other eustatic data. Geological Society of America Bulletin, 78, 437454. Shock, E.J., (1994). Personal Communication. Stapor, F.W., Jr., Mathews, T.D., and Lindfors-Kearns, F.E., (1991). Barrier island progradation and Holocene sea-level history in southwest Florida. Journal of Coastal Research, 7., 815-838. Stapor, F.W., Jr., Mathews, T.D., and Lindfors-Keams, F.E., (1988). Episodic barrier island growth in southwest Florida: A response to fluctuating Holocene sea level? Miami Geological Society Memoir 3. p. 149-202. Tanner, W.F., (1960). Florida coastal classification. In Trans. Gulf Coast Assoc. Geol. Soc., 10, p. 259-266. Walton, T.L., Jr., and Adams, W.D., (1976). Capacity of inlet outer bars to store sand. In Proceedings of 15th Conference on Coastal Engineering, ASCE, p. 1919-1937.

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102 APPENDICES

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APPENDIX 1. CORE LOGS Core# compaction-3% 145 em below MLW Depth (m) Percentage ofCaC03 MLW r---___,% G/Sc, % CaC03 o 100 2 1 3 2 4 3 .. ...... ."' ..... )_, 0 0 J .... '\ \.;' 0 )o..:, 0 ._ ')' .. .. 1--4/96 fine grained quartz sand mud lense flaser 8 shell hash lamina shell fragments laminated shells shells limestone Miscellaneous Misc. Fauna massive I laminated Aa Abra aequalis Ag Aequipectin gibbus At Anadara transversa A Anomia simplex B Balanus Be Brachidontes exustus Cf Cardita floridana Cc Chione cancellata C Crepidula spo Cp Crepidula plana Cm Crassinella mactracea Cr Coral Co Corbula spo De Diodora cayenensis Dv Donax variabilis E Echinodermata Gp Glycymeris pectinata Ls Laevicardium substriatum Lm Linga multilineata Lf Lucina Jloridana Ln Lucina nassula Np Noetia ponderosa 01 Olividea sp. 0 Ostrea spo Pg Plicatula gibbosa Sa Strombus alatus T Tellina spo Tr Tellina radiata Tt Tellina tampaensis Tb Terebra sp. Ti Trachycardium isocardia 103

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APPENDIX 1. (Continued) 104 BSP-1 compaction52% 51 em below MLLW Depth (rn) Percentage of MLW Core %G/S CaCO Misc. Fauna 0 %CaC03 0 1/99 14 massive 3/97 18 1 27/73 39 laminated Dv 33/67 53 Es 24/76 38 massive Cc laminated Cc 36/64 59 c 1 20/80 36 B Cc 40/60 67 laminated CcC At 40/60 65 laminated Cc 0 2 13/87 32 massive Cc 58/42 77 laminated AtCc 7/93 22 massive 7/93 15 Cc Cc 2 51/49 73

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APPENDIX 1. (Continued) BSP-2 Depth (m) compaction-37% 65 em below MLW MLW Core %GIS 0 -----., ... .. "1-5/95 1 1 .... : : : : : : f-0 /100 2 2 ...... 3 3 Percentage ofCaC03 % CaC03 0 100 105 Misc. Fauna EpCLf DvAtT EpTLf Cc Dv Lf DvCLf massive Cc A Dv DvAAgCm massive laminated

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APPENDIX 1. (Continued) BSP-3 compaction45% 63 em below MLLW Percentage ofCaC03 Depth (m) MLW Core 0 % G/S % CaC03 o 1oo 1 2 3 : : : : : :1-1/99 --,....-,... 1 ....... -,_-.,... 2 3 /92 :r---1/99 : ) : :': : .... i-2/98 0 ":'" :--. .,Jr-7 /93 ) I. .... J \; :--. J._.l..,.,. : : : : :r-1 /99 ..... . ,... ... . . . .. ( .. ...... 7 18 24 42 5 17 23 7 Misc. massive laminated massive laminated laminated laminated massive 106 Fauna Es Ep c Dv Ep Cc A OvA Cc Dv Lf TtCc Dv Cc B

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APPENDIX 1. (Continued) BSP-4 Depth (m) compaction-13% 36 ern below ML W MLW Core % G/S 0 ,..-.-.-.-.. : : : : : )-1/99 r-6 I 94 1 ...... r-0/100 1 ..... 2 ... .... :-:....: r-21/79 .. .. ...... 2 -: : :-: :r-0/100 3 3 Percentage ofCaC03 %CaC03 o 100 4 14 1 2 2 29 1 Misc. massive laminated massive 107 Fauna B Dv Td CcTt Dv At B Cc DvTtACp

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APPENDIX 1. (Continued) BSP-5 Depth (m) compaction-17% 32 em below ML W MLW Core %GIS 0 -. . -.. 1 1 _,_, -..,._ .. . -...... 2 2 .,_ .,... 3 3 Percentage of CaC03 %CaC03 100 Misc. massive laminated 108 Fauna

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APPENDIX 1. (Continued) BSP-6 Depth (m) compaction-14% 77 em below ML W MLW Core %G/S 0 1 1 2 ..... . .. 1/99 2 ,.. . . 2/98 -. 2/98 3 6/94 5/95 :\.: \: i: 11/89 7/93 9/91 3 1/99 2 3 3 2 2 3 Percentage of CaC03 100 109 Misc. Fauna massive Lf Dv Dv A PgDv CLf laminated Dv Lf Pg A TLfBe DvTt Cc CcCLf laminated At Cc A Cf EpTtAC

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APPENDIX 1. (Continued) BSP-7 compaction53% 20 ern below ML W Percentage of Depth (rn) CaC03 MLW Core %Caco3 100 0 1 1 2 2 3 3 ..... f3/97 _._ ... ... :-: ... _..___. ..... -.--.--. ------------..------.. ---------. 46/54 ____ ,__ .. __ '"'' .... : ;-.. ""' '""" ,... .._""";'. ,.,.... __ .-..._,':-" .:.... .... .::f61/39 .:_-:.. ,:.... ._. :_-.. ,_;..._. .......... ......: ..................... . '"" :-',...'":'-: 1--57/ 43 ._"":"<.. '.....:'....;:-' -'""'"" :::1--25/75 0 '-''""'"" ..... .'-. .,_. ) . \. ....... r . ) \... "\.. 1'-. -...; J \ :...., . : : : J: : _, \.". \ ... 16 37 16 82 78 33 Misc. laminated laminated laminated laminated laminated 110 Fauna A Cc Dv A AtDv CcAt CcCAg At Cc At Sa Ti CcA Cc CcSa Cc 01 CcTtAp Sa D v Ti

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APPENDIX 1. (Continued) BSP-8 Depth (rn) compaction-14% 98 em below MLW Percentage of CaC03 MLW Core % G/S 1 0 ..... % CaC03 o 100 2 : : : : : : f7/93 --------: : : : : : f-1/99 1 : : : : : : f-0/100 ...... ) : f-12/88 : : : : : : t-0/100 f-9/91 -:v . '"" '"'-' ...... r-... . : : : : 0 111 Misc. Fauna Tb massive Dv Cc laminated Cc laminated Cc PgAt laminated Dv massive Cc c laminated c LfTt Lf massive laminated B massive

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APPENDIX 1. (Continued) BSP-9 Depth (m) compaction49% 43 em below MLW MLW Core % G/S 0 : -_--_ : -.-:-1 1 2 2 3 3 .. :.--_ .. .. .._ .. :.. .. _:.. 12/88 -------------------.. _,_,_ ,._,_, --------. ..., r---35 /65 ----.-.---_-:.:. ... _:.":.: :. ... _ ... _-_ 0 ...... . /80 ."'\ ..... f-20 ... . 1-0/100 0 .-,-.. : .. -;;;_--. "'\.::.--;-.-,-.-:;.:: ... .--:: ,..._., ....... ....._._. ,_ ,_,_ .. _,_ .. '::. .. :-:-:::c .. .. "':: -:-: 57 Percentage ofCaC03 100 Misc. laminated 112 Fauna A

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APPENDIX 1. (Continued) BSP-10 Depth (m) MLW Core 0 2 1 3 2 4 3 compaction-33% 117 em below MLW %G/S .......-------, : : : : : :r--6/94 : : : : : :r-2/98 -.--.--':="-.--:--. : : : : : :r--1 /99 .... r--1/99 :... .. ,..... ......... ...... ... --:----:----:----:---. 18 8 29 5 6 21 . . t-12/88 16 : : v : : : 0 0 Percentage ofCaC03 100 Misc. massive laminated laminated laminated 113 Fauna Cc Sa At CfC Cc

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APPENDIX 1. (Continued) BSP-11 Depth (m) compaction16% 56 em below MLW MLW Core % G/S 0 : : : : : ) -0/100 1 : : : : : :f---0 / 100 1 2 : : : : : :f--0/100 -;..::f--12/88 2 :.:--1--43/57 '-;-.-;3 .... "1-2/98 ...... 3 : : : : : :1-0/100 4 4 Percentage ofCaC03 % CaC03 100 4 3 15 Misc. massive laminated laminated massive laminated massive 114 Fauna Td Cc Cc

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APPENDIX 1. (Continued) BSP-12 Depth (rn) MLW Core 0 1 1 2 2 compaction57% 75 belowMLW Percentage ofCaC03 .--------, %G/S %CaC03 10o \. . . } \; I ""\. ...... ...., } . l -') ;, Misc. massive laminated 115 Fauna CcAtDv Cc Cc Cc Cm Cc Cc Cc 1b

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APPENDIX 1. (Continued) BSP13 Depth (m) MLW Core 0 2 1 3 2 compaction-59% 111 em below MLW %G/S :\.:-:...:-: 11/89 .\.). 19/81 -5/95 .... ....... .. .... .. :: -:.:-:-:-:-: 0/100 ---------12/88 ..................... .. .. '-....... 11/ 89 ....... .) .,.... \. ...... ). 57/43 ,._, ...... r: .._ ). ._ ,_r )..;.., '\.'....:) ..... ) . \.-! \. .... > .>. . 116 Percentage ofCaC03 %CaC03 0 Misc. Fauna Lf CcDv 28 0 32 Cc A 21 DvC DvAt 6 laminated 56 At Dv Cc laminated CcDv At 41 Sa ACe 78 CcAt Cc Sa At SaNp At CcAt

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APPENDIX 1. (Continued) BSP-14 Depth (m) MLW Core 0 1 1 2 2 3 3 4 4 compaction47% 87 em below MLW %G/S 37/63 4/96 :.... 13/87 11/89 26/74 ;... 2/98 ;... . . . --------------1/99 17 / 83 0/100 ;.....:_ ""-' 4/96 ;... 25/75 .;,. -;....-;,.... 27/73 Percentage ofCaC03 %CaC03 0 100 73 23 35 23 45 10 35 Misc. laminated laminated burrow 117 Fauna Cc Lf At CcAtDv CcCTDv CcLf C Np At D v CmCc CcCp TCcAt TCcDv Lf T TCcTb TCc CcA

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APPENDIX 1. (Continued) BSP-15 compaction-3% 104 em below MLW Depth (m) MLW Core 0 %G/S 2 1 3 2 4 3 ... .._ : :-6/94 ,'-. 0 ..... : : : : : :-3/97 : : : : : )-3/97 ----------.,_.-: .-.,...., : : : : : :>-0/100 ..... 1--7/93 11/89 . . ..... 2/98 --------. .. .. .. ... . : : :1--0/100 %CaC03 33 Percentage ofCaC03 100 Misc. Fauna Dv A CDv 118 DvTrACp ALf AtLfECm laminated C Td Lf Cm laminated Cp laminated laminated 0 B c At laminated DvAtA B AtCrPg ALf

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APPENDIX 1. (Continued) NP-1 Depth (m) compac tion -41% 105 ern below MLW Percentage ofCaC03 MLW Core % G/S 0 .......----.-., % CaC03 _____ 1 00 2 1 .... . ..... . . . ) . .) . \ ...... . l... . ... } . ) . . _, \ :--. . ....: ) .. :_.., .. :r : . "' . Misc. 119 Fauna D v Np C c AC Cc A A g Cf Cc

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120 APPENDIX 1. (Continued) NP-2 compaction 6% 148 em below MLW Depth (m) Percentage ofCaC03 MLW Core %GIS %CaC03 0 100 Misc. Fauna 0 0 0 ..... 9 Cc ...... 5 .......... ,.... .-. Lf 8 laminated Co 2 4 ...... ..... 5 5 :-:..:-:..:-:.:::::::. 1 .... . 14 laminated 0 ,... 12 Cc . .. 4/96 16 laminated 0/100 4 0/100 5 3 0/100 4 Lf 0/100 9 laminated . . . 2/98 5 -. . 2 . "'-' 0/100 c "-' ... 1/99 0/100 TDvCp 0 0/100 4 0/100 A 3

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APPENDIX 1. (Continued) NP-3 compaction-3% 145 em below MLW Depth (rn) MLW Core %G/S 0 ...... -::. ,.,':."' 2 1 3 2 4 3 ... .,. ::.,.'::."1--16/84 . _ '-. 40 : : : : : :r-6/94 28 : : : : : : 0/100 3 ..... "r-7/93 22 .... ... "1--1/99 4 ..... . . . ---24/76 36 """'-'. . : : : : : :-0/100 . . . Percentage ofCaC03 100 Misc. massive laminated 121 Fauna Cc 01

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APPENDIX 1. (Continued) NP-4 Depth (rn) MLW Core 0 2 1 3 2 4 3 compaction10 % 114 em below MLW Percentage ofCaC03 %G/S % CaC03 r----100 0 0 0 0 r-0/100 3 '""--' 0 0 0 0 0 ,..._; 0 : : : : : :r1/99 4 0 0 0 0 f--0/100 3 : : : : : :r2/98 14 0 0 0 0 r-1/99 17 51 .... 122 Misc Fauna Np DvAt Cc Cc Tt A A Cc c At laminated Cc

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APPENDIX 1. (Continued) NP-5 Depth (m) MLW Core compaction33% 84 em below MLW 0 %GIS 1/99 1 1 2 2 3 4 3 -.-.-.-.-. --. '""'.-"' ........ ............. t-=.' . _, \. ....... '-.. """)" t ....; . f.8/92 . -). .. ) .. .. -t .. . .. _, ...... "'... 64 69 Percentage ofCaC03 100 123 Misc Fauna laminated t CcTtDv Co CcAtC 01 Cc Dv TtAtC AtOl CcSa Dv A CcAtC Lf Cc Cc Cc Dv At SaT AtDvCcA CcDv At laminated Cc TAtE CcDvA DvTLfA CcNpE CcAt Cc

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APPENDIX 1. (Continued) NP-6 Depth (rn) MLW Core 0 2 1 3 2 4 3 compaction7% 123 em below MLW %GIS : : : : : :r-0/100 _._ ------=.:-;.:.='-..::-t-42/58 I-:.:!, -,_ ,_ . .-t : : : : : : -3/97 ... ... ........... -. : : : : : : -1/99 ..... Percentage ofCaC03 %CaC03 0 100 5 12 72 11 76 37 5 124 Misc. Fauna massive Dv laminated Gp Cc DvAt massive E ADv CcA laminated Cc massive Cc

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125 APPENDIX 1. (Continued) NP-7 compaction -37% 215 em below MLW Depth (m) Percentage ofCaC03 MLW Core Misc. Fauna 0 CcAtA 60 Cc At Dv B 21/79 60 CcAtDv 25/75 64 CcAt 22/78 64 DvAtT 24 /76 64 laminated TAtCA 57 Lf 3 25/75 CcDv Lf 5/95 26 1 CcLf 31/69 71 LfAEp _""'_'-_' 31/69 74 laminated Cc AtCrC -""""""33 / 67 80 CcA CcAtC ........ 80 _""'_.__. 27 /73 At _...___ 50 / 50 77 CcB 4 2 / 9 8 10 2 5/95 CeO 0 /100 3/97 laminated CcSa 5 3

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APPENDIX 1. (Continued) NP-8 compaction17% 79 em below MLW Percentage Depth (rn) of CaC03 MLW % G/S % CaC03 r0 ___ 100 1 2 3 4 : : : : : :r--0/100 4 ;:;:-_ :-:,:. :-3/97 12 ,.... _.,. . .-.... '-. 1 : : : : : : 0/100 3 : : : : : }4/96 11 2 : : : : : : 0/100 :--. . . 0 0 0 0 ""vo 0 0 "'V 0 0 : : : :,_ 0/100 3 o""-.;o 0 0 0 0 0 0 "-J 0 ... ... ... _-_ ... _-_-__ ... --3 0 0 0 0 0 1/99 . ... 5 0 0 0 0 011/99 4 4 0 0 0 0 0 '-'. . . 126 Misc. Fauna massive TtCc At Cc laminated

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APPENDIX 1. (Continued) NP-9 compaction% 80 em below MLW 1 . . --.--. -. . -2 -:: -:.-:;. f--10/90 : : : : : f--1/99 ..:--: ..:-f--15/85 ..., _, ........ . 2 3 ... . f--0/100 3 4 41 46 15 16 5 33 3 Percentage ofCaC03 0 100 Misc. laminated Fauna Cc c AtCcOA Dv AtCc Lf DvLfC TCc Lf CcTLfCmE CCpB TC At Cc Ti Ag A Ti 127

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APPENDIX 2. SEDIMENT ANALYSIS OF VIBRACORE SAMPLES. 128 Percentage % CaC03 sand core ravel sand sand mean STD Big Sarasota Pass BSP-1 12 1.50 98.50 12.67 2.35 0.57 24 3.47 96.53 15.34 2.38 0.53 36 26 64 73.36 17.26 2 .19 0.65 48 32 99 67.01 30.02 2.11 1.98 60 23.99 76.01 18.02 2.11 0 88 72 35.71 64.29 35.70 1.94 0.78 84 20 .15 79 85 19.84 2 04 0 78 96 40.34 59.66 45.35 1.92 0 76 108 39 32 60.68 42. 78 1.87 0 84 120 13. 40 86 60 21.23 2.10 0.66 132 58.04 41.96 45.33 1.88 0 .83 144 7.18 92 82 15.54 2.30 0.52 156 6.58 93.42 8.71 2.62 0.48 162 51. 09 48 .91 44 86 1.56 0.94 BSP-2 25 4 .71 95.29 18.19 2.14 0.77 48 22.82 77.18 27 72 2 00 0.80 85 19.95 80.05 23.57 2.11 0.71 132 0.44 99.56 3.60 2.75 0 25 175 20 99 79 .01 32 96 1.87 0.88 191 31.24 68.76 57 .81 1.36 0.92 200 75.41 24 59 70 67 0.62 0.51 BSP3 30 0.97 99.03 5 72 2 .56 0.39 70 5.58 94.42 13. 09 2.43 0.62 110 15.10 84.90 10.64 2 .33 0.70 152 7 52 92.48 37.01 1.81 0.84 165 0 .03 98.93 5 00 2 .63 0.38 188 2.13 97.87 15. 09 2 .31 0 50 205 7 .16 92.84 16.97 2.43 0.46 220 0.37 99.63 6 94 2.36 0.49 BSP-4 10 0.59 99 .41 3 74 2.57 0.33 41 6 .23 93.77 8.74 2.48 0 .55 75 0 00 100.00 1.45 2 76 0 32 110 0 00 100 00 2.19 2 82 0.21 148 0.10 99.26 2.17 2.52 0.40 156 21.12 78.88 9.92 2.48 0.40 185 0.00 99 68 1.28 2 64 0.40

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APPENDIX 2 (Continued) 129 Percentage %CaC03 sand core ravel sand sand mean SID BSP-6 0.00 100.00 1.53 2.72 0 57 30 0.40 99.60 2.27 2.63 0 .53 45 0.14 99.86 2.89 2.68 0.23 60 0.08 99 92 1.72 2.69 0.29 75 0 .03 99.97 2 32 2.70 0.19 90 0.50 99.50 2 34 2 .73 0.23 105 0.00 100.00 1.46 2 70 0.17 115 0 56 99.44 1.59 2 76 0.22 130 0.00 100.00 1.45 2.61 0 19 145 0 05 99.95 2 .16 2.69 0.18 160 1.45 98 55 2.24 2 62 0.63 171 2 .21 97.79 4.07 2.65 0.31 182 2.25 97 75 4.74 2.63 0.22 193 5 79 94 .21 16.85 2.37 0 .51 205 4 .70 95.30 12.07 2.49 0.44 220 10 77 89 23 24.42 2.02 0.73 233 7.24 92.76 16.76 2.10 0.66 246 9.35 90 65 17.74 2.35 0.54 261 0 53 99.47 5 .13 2.57 0.28 BSP-7 25 3.47 96.53 12.86 2.34 0.48 70 45.65 54.35 39.72 1.87 0.89 100 2 .32 97.68 14.22 2.45 0.49 134 60.73 39.27 52.79 1.62 0.87 155 56.80 43 .20 48.28 1.95 0.81 180 24 97 75.03 10.70 2.54 0.40 BSP-8 30 7.40 92 60 5.94 2.63 0.37 60 1.12 98 88 8.18 2.60 0.44 90 0.44 99.56 4.12 2.67 0.46 107 12 31 87.69 25 35 2.35 0.70 130 0 04 99.96 3.07 2.65 0.28 152 9.26 90.74 23 .11 2 19 0.85 195 0 00 100.00 3.28 2.69 0 25 BSP-9 15 12 02 87.98 51.66 1.65 0.88 50 34.96 65.04 60. 55 1.34 0.78 75 19 .51 80.49 25.32 2.16 0.79 80 0.38 99.62 5 38 2.49 0.25 115 61.12 38 88 53.68 1.47 0.98 BSP-10 30 6.02 93.98 12.48 2.51 0.43 70 2 .00 98 .00 6.49 2 60 0.31 108 15.21 84.79 16.28 2.38 0.68

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APPENDIX 2. (Continued) 130 Percentage % CaC03 sand core ravel sand sand mean STD BSP-10 0.55 99.45 4.52 2.78 0.23 135 30.92 69.08 40.12 2.03 0.96 160 0.53 99.47 5.72 2.53 0.32 171 3.35 96.65 18.17 2.42 0.39 215 11.52 88.48 4.77 2.74 0.33 BSP-11 30 0.36 99.64 3.62 2.52 0.24 60 0.25 99.75 2.72 2.55 0.19 94 0.46 99.54 15.01 2.37 0.33 120 0.10 99.90 4.27 2.46 0.21 150 1.50 98.50 10.66 2.52 0.34 165 12.30 87.70 25.65 2.10 0.68 190 42.63 57.37 21.62 2.07 0.80 220 1.75 98.25 8.30 2.52 0.37 254 8.74 91.26 12.92 2.43 0.47 290 0.44 99.56 5.91 2.62 0.33 BSP-13 30 10.53 89.47 19.66 2.16 0.74 43 18.55 81.45 16.90 2.29 0.65 60 4 76 95.24 16.61 2.42 0.56 88 0.00 100.00 5.74 2.60 0.21 91 12.45 87.55 49.49 1.41 0.81 111 11.31 88.69 33.72 1.86 0.80 120 56.73 43.27 48.33 1.77 0.85 BSP-14 15 37.11 62.89 56.69 1.19 0.85 40 4.15 95.85 19.66 2.31 0.53 62 13.08 86.92 24.91 2.02 0.74 78 10.72 89.28 14.24 2.30 0.59 98 25.61 74.39 26.13 2.08 0.85 112 1.85 98.15 7.83 2.48 0.34 134 1.20 96.23 33.83 2.18 0.66 165 1.23 98.77 15.41 2.30 0.57 181 17.42 82.58 36.32 1.94 0.78 208 0.05 99.95 3.64 2.66 0.21 242 3.82 96.18 11.99 2.41 0.45 286 25.49 73.24 6.18 2.63 0.31 295 26.77 73.23 15.10 2.44 0.48 BSP-15 20 5.81 94.19 10.79 2.13 0.69 50 2.95 97.05 8.71 2.28 0.54 80 2.61 97.39 5.22 2.47 0.34 120 0.10 99.90 1.89 2.69 0.39 152 5.99 94.01 28.27 1.98 0.75

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APPENDIX 2 (Continued) 131 Percentage %CaC03 sand core ravel sand sand mean STD BSP-15 7.23 92.77 11.78 2.40 0.61 11.01 88.99 13.21 2.65 0.62 182 2.18 97.82 3.36 2.53 0.46 223 7 .63 92.37 18. 26 2.32 0.65 250 0 20 99.51 2.91 2.66 0.32 New Pass NP-2 14 1.97 98.03 6.90 2.56 0.28 27 0.60 99.40 4.66 2.60 0.35 40 2.12 97.88 6.46 2.59 0.34 53 0.56 99.44 3.49 2.59 0.29 66 0.36 99.64 4.56 2.65 0.30 80 0 34 99.66 4.63 2.67 0.27 93 1.26 98.74 12. 76 2.43 0.51 103 0 62 99.38 11.56 2.43 0.51 113 4.17 95.83 12.41 2.51 0.39 120 0.18 99.82 3.38 2.54 0.55 133 0.26 99.74 4 29 2.59 0.23 146 0.02 99.98 3 .65 2.53 0.23 160 0 .23 99.77 8.39 2.50 0.58 173 1.79 98.21 3.57 2 66 0.27 186 0.14 99.86 2 .51 2.66 0.22 200 1.61 98.39 3 .87 2.68 0.20 213 0.18 99.82 2 .19 2.70 0.20 226 0.27 99.73 3.16 2.70 0.20 240 0.13 99.87 3.63 2.64 0.24 NP-3 15 15.46 84.54 29 .03 1.82 0.93 40 5 .51 94.49 23.53 2.00 0.81 90 0 .09 99.91 2.46 2.52 0.33 129 6 .88 93.12 16.25 2.07 0.81 170 0.78 99.22 3 .55 2.63 0.24 208 24.27 75.73 15.27 2 .12 0.93 245 0.05 99.95 1.90 2.73 0.57 NP-4 40 0.48 99.52 2.74 2.66 1.69 80 0.98 99.02 3 .10 2.73 0.24 120 0.06 99.94 2.57 2.66 0.27 155 2.32 97.68 11.97 2.21 0.61 175 0.82 99.18 16.14 2.28 0.54 195 27 .04 72.96 32.04 1.98 0.73

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APPENDIX 2. (Continued) 132 Percentage %CaC03 sand core ravel sand sand mean STD NP-5 1.08 98.92 32.10 1.98 0.60 40 29.49 70.51 48.74 1.56 0.88 80 35.54 64.46 52.26 1.58 0.76 110 47.23 52.77 38.25 1.52 1.00 125 11.07 88.93 42.30 1.68 0.86 135 27.39 72.61 27.84 1.90 0.96 180 7.75 92.25 10.70 2.47 0.54 NP-6 20 0.24 99.76 4.92 2.63 0.30 39 3.44 96.56 8.42 2.59 0.44 75 42.04 57.96 51.70 1.41 0.87 105 3.14 96.86 8.32 2.57 0.68 126 35.53 64.47 62.82 1.25 0.84 140 11.80 88.20 28.91 2.14 0.76 170 0.57 99.43 4.06 2.62 0.64 NP-7 12 29.42 70.58 42.94 1.61 0.67 24 21.27 78.73 49.60 1.59 0.67 36 25.42 74.58 51.42 1.59 0.78 48 22.09 77.91 53.25 1.52 0.72 60 23.65 76.35 52.48 1.38 0.64 72 25.38 74.62 42.38 1.66 0.77 84 5.47 94.53 21.41 2.09 0.77 96 30.82 69.18 58.35 1.40 0.92 108 31.24 68.76 62.88 1.12 0.76 120 33.20 66.80 69.96 1.07 0.73 132 27.20 72.80 72.25 1.29 0.80 144 50.19 49.81 54.79 1.28 0.86 156 2.18 97.82 7.84 2.56 0.43 168 4.72 95.28 7.74 2.63 0.41 180 0.46 99.54 3.65 2.73 0.38 192 2.91 97.09 23.92 2.46 0.57 NP-8 25 0.29 99.71 3.52 2.62 0.52 60 2.70 97.30 9.31 2.59 0.47 85 0.16 99.84 2.58 2.62 0.25 115 3.82 96.18 7.22 2.62 0.43 150 8.67 91.33 8.86 2.48 0.46 185 0.41 99.59 2.41 2.67 0.37 225 0.00 100.00 2.59 2.77 0.19 285 0.52 99.48 4.14 2.58 0.26 325 0.45 99.55 3.47 2.63 0.24

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APPENDIX 2 (Continued) 133 Percentage % CaC03 sand core ravel sand sand mean sm NP-9 16 94 83.06 28 .61 2.36 0.62 50 15.74 84 .26 35 .71 1.87 0.71 90 4 62 95 38 11. 07 2 35 0.44 115 9 82 90.18 6 .75 2.65 0 35 130 0 77 99.23 4 08 2 59 1.66 170 14 .85 85.15 21.47 2.27 0 64 220 0 14 99 86 3 .31 2 66 0.23

PAGE 146

APPENDIX 3 SEDIMENT ANALYSIS OF SURFACE SAMPLES. 134 Percentage % CaC03 sand ravel sand sand mean STD Big Sarasota Pass 1 63. 66 36 34 45.14 1.83 0.90 2 48.65 51.35 40.80 1.38 0 .91 3 5 97 94 .03 11.62 2.49 0 38 4 12.43 87 57 22 .03 2 20 0 59 5 1.08 98.92 4 .55 2.75 0 67 6 0.49 89 .73 2.39 2 .96 0 27 7 0 69 88 26 2.51 2.86 0 20 8 0.00 96 .21 2.14 2.81 0 24 9 0.76 97 37 3 .11 2.83 0.29 10 0 68 94.08 4 .18 2 .76 0 .35 11 0 90 99 .10 2 .93 2 .73 0.26 12 0 50 99 50 2 57 2 .73 0.24 13 0 .15 99 .85 2 .61 2 .71 0.19 14 0.14 99 .86 2.13 2 .55 0 .25 15 0.03 99 97 1.44 2.64 0 26 16 3 86 96.14 7.19 2.53 0.31 17 0 00 100 00 2.25 2.67 0 .26 18 0 .93 98.59 5.89 2.47 0 .35 19 1.07 98.93 13. 26 2 36 0 .23 20 0.30 99 .70 4 .79 2 .55 1.70 21 0.31 99.69 4.11 2.60 0 .33 22 0.34 99 66 2 .70 2 .58 0 .23 23 0.43 99 57 2.40 2 66 0.24 24 0.09 99 .91 2.97 2.68 0.29 25 1.11 98. 89 1.75 2.65 0.41 26 0.13 99 87 1.03 2.65 0 .19 27 0.08 99 92 1.59 2 .61 0 20 28 29 54 70.46 60 00 1.55 0.96 29 54 56 45.35 71.25 1.40 0 80 30 79 .23 20 .75 87 09 0 .92 0.54 31 64 .15 35.85 55.22 1.35 0 .91 32 81.62 18. 38 83.13 1.26 0.87 33 35.27 64.73 37.69 1.99 0.75 34 0 58 99.42 3.75 2 .75 0.29 35 0 50 99 50 2.70 2 .78 0.28 36 0 74 99 26 3.80 2 .51 0.22 37 4 .31 95.69 4.65 2 60 0.39 38 1.33 98.67 5 .86 2 .75 0 39

PAGE 147

APPENDIX 3 (Continued) 135 Percentage % CaC03 sand ravel sand sand mean STD Big Sarasota Pass 39 0.08 99 92 2.95 2 .82 0 .23 40 0.73 99.27 4.28 2.59 0 .33 41 14.31 85. 69 15.05 2 .53 0.47 42 0.62 99.38 3 24 2 64 0 .23 43 0 .75 99.25 3 .51 2.49 0.41 44 7 .95 92.05 19.82 2.29 0.64 45 0.27 99 .73 1.74 2.52 0.18 46 0.17 98.25 2.28 2.85 0.30 47 0.27 98.57 2.50 2.79 0.23 48 0 50 98. 94 2 60 2 .74 0.20 49 1.01 98. 99 3 09 2 .70 0.21 50 0 02 99 .98 2 .11 2 70 0 .18 51 0.56 97 .28 7.45 2 .85 0.57 52 1.64 97 24 5 .61 2 .71 0 27 53 0.22 99.46 2.55 2.78 0.43 54 0.14 99 86 0.06 2.66 0.23 55 0.28 99 .72 2.30 2.68 1.72 56 0 .55 99.45 1.58 2.66 0 .19 57 0.41 98.24 5 .65 2 .78 0.29 58 0 .14 97.31 2 .81 2 .83 0 .28 59 8.27 91.46 8 27 2 .75 0.42 60 3 00 97 00 6.17 2.67 0 .33 61 0 90 99 .10 3 .04 2.65 0 22 62 1.80 97 .05 4 .91 2 .86 0.33 63 0.14 99.27 2.50 2.80 0 26 64 5.90 94 .10 8.95 2 .55 0.47 65 3 .11 96 .16 4 99 2 .75 0 .35 66 14.42 85. 58 27 36 2 .10 0 .72 67 0.12 99.56 2 .04 2.71 0 .25 68 1.22 98.78 2 .88 2.61 0 .24 69 0.46 99 54 4.46 2 .53 0 .23 70 3.28 96 .72 8.76 2.43 0 32 71 15.45 84 .55 31.64 2.22 0 .62 72 70.85 29.15 71.77 0.97 0.71 73 0.00 100 00 0.69 2 56 0.17 74 0.00 100.00 0 57 2 36 0.38 75 24.00 76 00 62 82 1.25 0 .73 76 65 .11 34 89 32.96 1.99 0 86 77 65.19 34 .81 41.63 1.85 0.82 78 47.45 52.55 39.30 1.82 0 80

PAGE 148

APPENDIX 3 (Continued) 136 Percentage % CaC03 sand ravel sand sand mean SID New Pass 1 23 .51 76.49 91.96 1.14 0.58 2 64 77 35.23 71.85 0 64 0.41 3 0.33 99 78 3 22 2.63 0.28 4 18 62 81.38 14 .83 2 62 0 55 5 0.43 99.57 3 85 2 56 1.75 6 13.49 86.51 20.98 2.09 0.70 7 0 82 99 .18 2.95 2 80 0 24 8 2.12 97.88 2.86 2.61 0.42 9 4 23 95. 77 5.34 2.41 0.47 10 0 09 99 .91 5 24 2 39 0.40 11 2.77 97 23 16.19 2.40 1.94 12 20.69 79 .31 15.03 2.30 0 55 13 29.90 70 10 72 54 1.00 0 54 14 50.43 49. 57 86.28 0 .93 0.47 15 61.36 38 64 45 19 1.64 0.93 16 7 05 92.95 7 66 2 57 0.34 17 2.84 97.16 9.19 2.56 0.41 18 0.02 99.98 3.42 2 .51 0.36 19 0 06 96 60 2.10 2 .91 0 .21 20 0.05 98 22 1.42 2 .91 0 19 21 2 00 97 .03 2 55 2.74 0.23 22 1.85 98 .15 5 79 2.64 0.52 23 0 .03 99 97 4.85 2 55 0 27 24 0.58 99.42 3.67 2.52 0.23 25 0.74 99 26 4 57 2 66 0.34 26 1.02 98.98 4.15 2 69 0 37 27 0.28 99 72 2 .61 2 63 0.36 28 5.84 94 16 13. 84 2.41 0.45 29 36. 70 63. 30 28.47 1.86 0.73 30 0 20 99 80 5.16 2.47 0.30 31 0 93 99.07 5.27 2.45 0 22 32 2.09 97.91 6.46 2.61 0 20 33 1.09 98.91 6.53 2 52 0.44 34 1.70 98.30 10 .55 2 32 0 33 35 21.21 78 79 55 60 1.47 0 77 36 22 39 77 .6 1 20 26 2.37 0 85 37 0 96 99.04 6 74 2.46 0.48 38 0 07 96.64 5 52 2 87 0 .14

PAGE 149

APPENDIX 3. (Continued) 137 Percentage % CaC03 sand ravel sand sand mean STD New Pass 39 0.46 98.81 2.44 2.70 0 .23 40 5 .11 94.89 8 70 2 .50 0.40 41 4 08 95 92 5 70 2.53 0.30 42 1.22 98 78 4.08 2.67 0 27 43 4 54 95.46 7.30 2.47 0.29 44 45 76 54.24 41.30 1.97 0.80 45 25 87 74 .13 25 87 2.06 0.87 46 57.52 42.48 57.52 1.65 0.85 47 0 66 99.34 0.66 2 72 0.25 48 87 63 12. 37 3 79 2.94 0 22 49 92.49 7.51 2 37 2 .81 0.21 50 86.29 13.71 3 .91 2.44 0 .21 Lido Key 1 2.41 97.59 4 76 2.47 0 29 2 11.00 89 00 23. 04 2 .05 0 67 3 9 76 90 24 26.44 1.95 0.70 4 10.31 89 69 54.90 1.36 0 .73 5 2 .18 97 82 27.23 1.99 0.67 6 27 87 72 .13 66 .55 1.24 0 79 7 6 90 93.10 8 48 2.40 0 34 8 2 79 97 .21 16. 92 2.09 0 58 6 27.87 72 .13 66 .55 1.24 0 79 7 6 90 93.10 8.48 2.40 0.34 8 2 79 97 .21 16.92 2 .09 0 58

PAGE 150

APPENDIX 4. DISTRIBUTION OF SURFACE SEDIMENTS 2 .H5 2.7 1 2 .X3 1.36 2.10 2 7 5 2.55 2 .86 2 g 2.78 2.96 2.80 2.82 ::!.75 2.8 1 2.7 4 2.83 5 2.67 .2.65 2 75 2.76 2.73 2.70 2.64 2 .65 e2.c.s 2.66 500 meters Sand mean g rain s ize in phi. 2.71 e2.ss 2 .60 2 .61 .2. 5 5 2.53 Big Sarasota Pass 2.43 138

PAGE 151

APPENDIX 4. (Contin ued) 139 27.Jn e 5 h 5 7 .45 2.2H 5.61 2.SI 8 .95 2 50 2.51 2.55 2.97 500 meters 2.39 2.5 0 2 .95 2 .14 2 60 2.40 8 .27 3.11 6.17 4.1 8 3 .09 3.75 71.77 31.64 2.1 3 13.26 2 70 2 .88 .1. 5 Weight percent of CaC03 of sand. Big Sarasota Pass es.s9 .25 3 .2-1

PAGE 152

APPENDIX 4. (Continued) Longboat Key + 2.47 .::!.69 2 66 c ( e 2.52 2.53. :!55. 2.50 2.M 1.65 2.7 0., 2 .74. 2 .91. 2.9 1 :!. 9 4 500 meters Sand mean grain size in phi. 2 .61 :!52 140

PAGE 153

APPENDIX 4. (Continued) + 500 meters Longboat Key 5.70 s 8.70 2.44 2.55. 1.-12 5 .79 es7.s2 7.66 Q .9.19 0,. o o.27 .2lf20.26 ew.ss 3.42 .6.74 6,3 .6.46 es.s2 2.10 3.79 Weight percent of CaC03 of sand. 141

PAGE 154

e b b f 1 0 0 d e b b f I 0 0 d Big Sarasota Pass Tidal prism 8/18-19/94 proximal Time CTOM-ctional hydraulic --------10 :30 18006 .86 10 .72 11:30 17922 .93 10.67 12:30 17587 .22 10 .47 1:30 17167.58 10 .22 2:30 16580.08 9 .87 3:30 15908 .66 9.47 4:30 15237.24 9.07 5 :30 14732 .59 8 .77 6 :30 14480 81 8.62 7 :30 14310.80 8 .52 8 :30 14478 .66 8 .62 9:30 14898.30 8.87 10:30 15485.79 9.22 11:30 16073.29 9 .57 12 :30 16409 .00 9 .77 1 :30 16492.93 9 .82 2 :30 16492.93 9 .82 3 :30 16409 .00 9 .77 4 :30 16576.86 9 .87 5:30 16660.78 9 .92 6:30 16576.86 9 .87 7:30 16492.93 9.82 8:30 16912.57 10.07 9:30 17416 14 10.37 10 :30 17751.85 10 .57 11:30 18006.86 10.72 tidal Depth at velocity .. ---.. -2 .35 10 .69 0.328 2 .30 10.64 0 .820 2.10 10.44 1.640 1.85 10 19 2 132 1.50 9 .84 2.460 1.10 9.44 2 .706 0 .70 9 .04 2.667 0 40 8 74 2.191 0 25 8 .59 1.151 0.20 8 54 0.315 0.30 8.64 1.814 0.55 8 .89 2.319 0.90 9.24 2.467 1.25 9.59 2.178 1.45 9 .79 1.453 1.50 9.84 0.052 1.50 9.84 1.102 1.45 9 .79 0 .745 1.35 9.69 0.276 1.30 9.64 1.181 1.35 9 .69 2.463 1.50 9.84 2 .850 1.75 10.09 2 575 2.05 10 .39 2.526 2.25 10.59 2 .109 2.35 10.69 0.790 vel ocity Diochargc area under __ ... l'i ..... ---, ,------0.33 5916.73 10319 .89 0.82 14723.05 21809.45 1.64 28895.84 32783.13 2 14 36670. 41 38768.99 2 46 40867. 57 42003.01 2 71 43138.45 41929.99 2 .67 40721.52 36536.82 2 .20 32352. 11 24530.89 1.15 16709.67 10604.21 0 .31 4498.75 15358 85 1.81 26218.95 30355 .99 2 .32 34493 .03 36314. 91 2 .46 38136.79 36544.80 2.17 34952.80 29379.88 1.45 23806.95 12335.60 0 .05 864.25 9506.72 1.10 18149.19 15174.12 0 74 12199 .05 8410.68 0.28 4622. 31 12333.67 1.20 20045 .02 30685.36 2 .49 41325.70 44132.55 2.85 46939. 41 45210 71 2 57 43482.02 43702. 14 2 .52 43922. 2 7 40653.93 2 11 37385.59 25822. 46 0 .79 14259 .33 7129.67 sum of volume t i da l pri sm ___ -248966 .48 8 .96E+08 volume flood ft3 1.44E+0 9 147954 .42 5 .33E+08 volume ebb ft3 370!6.43 l.33E+08 250951.51 9.03E+08 tidal prism 3.49E+0 7 volume flood m3 4 .07E+07 volume ebb m3 2 .92E+07 > :g ti1 z 0 Ul ::j 0 > r"' C/) -0 z -N

PAGE 155

e b b f 0 0 d e b b f 0 0 d Big Sarasota Pass Tidal prism 8/18-19/94 distal Time cross-sectional hydraulic --------10:30 9533.36 12.71 11:30 9495.70 12.66 12:30 9346.14 12.46 1:30 9158.91 12.22 2:30 8896.37 I 1.86 3:30 8596.16 11.46 4:30 8295.96 11.06 5:30 8071.08 10.76 6:30 7958.10 10.61 7:30 7920.44 10.56 8:30 7995.76 10.66 9:30 8182.98 10.91 10:30 8445.52 11.26 11:30 8708.07 11.61 12:30 8857.63 11.81 1:30 8895.29 11.86 2:30 8895.29 11.86 3:30 8857.63 I 1.81 4:30 8782.31 11.71 5:30 8744.65 11.66 6:30 8782.31 11.71 7:30 8895.29 11.86 8:30 9082.52 12.11 9:30 9307.40 1241 10:30 9456.96 12.61 11:30 9532.28 12.71 tidal -. -.. 2.35 2.30 2.10 1.85 uo 1.10 0.70 0.40 0.25 0.20 0.30 0.55 0.90 1.25 1.45 uo uo 1.45 1.35 1.30 1.35 uo 1.75 2.05 2.25 2.35 Depth at velocity velocity Di!IChargc -, ... -----c--........ .._I_ 11.16 0.253 0.28 2623.89 11.11 0.485 0.53 5025.15 10.91 1.676 1.83 17102.91 10.66 2.762 3.02 27670.52 10.31 3.231 3.54 31531.37 9.91 3.752 4.13 35508.10 9.51 2.840 3.14 26037.64 9.21 2.650 2.94 23706.66 9.06 0.243 0.27 2144.05 9.01 0.220 0.24 1933.05 9.11 0.768 0.85 6808.39 9.36 0.571 0.63 5167.78 9.71 0.774 0.85 7209.61 10.06 0.476 0.52 4552.90 10.26 0.380 0.42 3698.39 10.31 0.121 0.13 1184.19 10.31 0.305 0.33 2976.48 10.26 1.109 1.22 10776.33 10.16 0.876 0.96 8447.27 10.11 0.092 0.10 882.43 10.16 0.807 0.89 778288 10.31 0.823 0.90 8033.28 10.56 0.538 0.59 5348.25 10.86 0.633 0.69 6434.71 11.06 0.253 0.28 2604.50 11.16 0.485 0.53 5042.37 area tmdcr aum of di!!Charge volume ---............. .. ........... --3824.52 171004.87 6.16E-t{)8 11064.03 22386.72 29600.95 33519.73 30772.87 24872.15 12925.35 2038.55 4370.72 28995.69 1.04E-t{)8 5988.09 6188.70 5881.25 4125.64 2441.29 2080.33 18568.53 6.68E-t{)7 6876.40 9611.80 4664.85 37830.87 1.36E-t{)8 4332.65 7908.08 6690.77 5891.48 4519.60 3823.43 2521.18 tidal prllllll --4.62E-t{)8 volume flood ft3 2.41E-t{)8 volume ebb ft3 6.82E-t{)8 tidal prilllll l.31E-t{)7 volume flood m3 6.82E+06 volume ebb m3 1.93E-t{)7 ;> z 0 >< Y' ,-.. s c:: 0. ......., ....... VJ

PAGE 156

New Pass Tidal prism l 0/22-23/94 proximal Time CTOftHCCtional hydraulic f 0 0 d e : ) b b ) f , I : ) ) 10:00 11:00 12:00 1:00 2 :00 3:00 4:00 S:OO 6:00 7:00 8:00 9:00 10:00 11:00 12:00 1:00 2:00 3:00 4:00 S:OO 6:00 7:00 8:00 9:00 10:00 -----------SSS2.16 8.SS S682.36 8.7S S812.SS 8.9S 6072.94 9.3S 6267.70 9.6S 6462.46 9.9S 6S28.09 10.0S 6462.46 9.9S 6397.90 9.8S 6332.26 9.7S 6332.26 9.7S 6332.26 9.7S 64S6.00 9.94 6S93.73 10.1S 6789.S6 10.4S 698S.39 10.7S 7049.9S 10.8S 698S.39 10.7S 6789.S6 10.4S 6S93.73 10.1S 6332.26 9.7S 6072.94 9.3S S878.19 9.0S S682.36 8.7S S617.80 8.6S tidal ------0.00 0.20 0.40 0.80 1.10 1.40 l.SO 1.40 1.30 1.20 1.20 1.20 1.40 1.60 1.90 2.10 2.20 2.10 1.90 1.60 1.20 0.80 o.so 0.29 0.10 Depth at velocity velocity Discharge -----------------S.34 2.342 3.19 17737.13 S.S4 2.6SO 3.S8 203S9.S2 S.74 2.S78 3.46 20088.39 S.86 1.883 2.S6 1SS63.16 6.16 0.8SO 1.14 7160.31 6.46 0.623 0.83 S3SS.69 6.S6 1.092 1.4S 9449.0S 6.46 1.899 2.S3 16320.77 6.36 1.469 1.96 12S47.97 6.26 1.178 l.S8 9988.46 6.26 1.391 1.86 11796.9S 6.26 1.197 1.60 101SS.39 6.46 0.771 1.02 6613.16 6.66 1.1SS 2.32 1S281.77 6.96 l.S74 2.06 13980.79 7.16 0.302 0.39 27S7.13 7.26 0.981 1.28 901S.66 7.16 1.811 2.37 16S42.79 6.96 2.322 3.04 20621.66 6.66 2.490 3.29 21680.12 6.26 3.014 4.04 2SS69.33 S.86 2.916 3.97 24103.92 S.S6 2.S19 3.47 20422.62 S.3S 1.804 2.SO 14181.49 S.16 0.90S 1.27 71Sl.47 area IUider IUJI1 of volwne -------------------19048.33 74717.79 2.69E-+{)8 20223.96 1782S.77 11361.73 62S8.00 7402.37 S6882.S7 2.0SE-+{)8 12884.91 14434.37 11268.21 10892.70 10976.17 S3308.16 1.92E-+{)8 8384.28 10947.47 14631.28 8368.96 S886.40 164243.36 S.91E-+{)8 12779.22 18S82.23 211S0.89 23624.73 24836.62 22263.27 17302.06 10666.48 71Sl.47 tidal prism tidal prism -----6.28E-+{)8 1.78E-+{)7 volumellood volwnellood ft3 m3 4.61E-+{)8 1.31E-+{)7 volwne ebb volume ebb ft3 m3 7.96E-+{)8 2.26E-+{)7 > 'i::1 z 0 Y' ......._ s r:::: 8. '-" .....


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