An Investigation of the Late Quaternary Morphology of Mobjack Bay, VA and Application of a Facies Model
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W&M ScholarWorks Dissertations, Theses, and Masters Projects Theses, Dissertations, & Master Projects 1994 An Investigation of the Late Quaternary Morphology of Mobjack Bay, VA and Application of a Facies Model Donna Angela Milligan College of William and Mary - Virginia Institute of Marine Science Follow this and additional works at: https://scholarworks.wm.edu/etd Part of the Geomorphology Commons Recommended Citation Milligan, Donna Angela, "An Investigation of the Late Quaternary Morphology of Mobjack Bay, VA and Application of a Facies Model" (1994). Dissertations, Theses, and Masters Projects. Paper 1539617677. https://dx.doi.org/doi:10.25773/v5-hcr7-jh16 This Thesis is brought to you for free and open access by the Theses, Dissertations, & Master Projects at W&M ScholarWorks. It has been accepted for inclusion in Dissertations, Theses, and Masters Projects by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. AN INVESTIGATION OF THE LATE QUATERNARY MORPHOLOGY OF MOBJACK BAY, VA AND APPLICATION OF A FACIES MODEL A THESIS PRESENTED TO The Faculty of the School of Marine Science The College of William and Mary In Partial Fulfillment Of the Requirements for the Degree of Master of Arts BY Donna Angela Milligan Fall, 1994 This thesis is submitted in partial fulfillment the requirements for the degree of Master of Arts (IniG&ilck ' u L O b O /f t m _ Donna Angela Milligan (j Approved, November 19 94 / / L. Donelson Wright *■ n D . Boon / 9Ll ^Cil C ^ C. Scott Hardaway, J ' t . ACKNOWLEDGMENTS I would like to offer sincere appreciation to my advisory committee: Carl Hobbs, Don Wright, John Boon, Scott Hardaway and Bob Diaz for their help, guidance, and particularly their patience in formulating the basis for this thesis as well as their helpful discussions and comments. Special thanks to Carl Hobbs who not only instructed me on the collection of seismic data, but also spent many hours on the water gathering it in addition to helping immensely with the interpretation. I am indebted to all those who volunteered to collect the data particularly Patricia Tiedeman, Nicole Scott, and George Thomas. Thanks to Cynthia Harris, Beth Marshall, and Frank Farmer who provided immeasurable support. Finally, I'd like to thank the husband, Reese, for his moral support, encouragement, patience, and understanding. TABLE OF CONTENTS Page ACKNOWLEDGMENTS .................................................................................... iii LIST OF FIGURES ............................................................................................. vi LIST OF TABLES ............................................................................................... viii ABSTRACT ........................................................................................................ ix I. INTRODUCTION................................................................................... 1 General Statements .................................................................. 1 Stratigraphy Resulting from Sea Level Oscillations 3 Study Area Description ............................................................. 6 II. OBJECTIVES........................................................................................ 9 I I I . CHESAPEAKE BAY QUATERNARY HISTORY.............................. 13 Geologic History ............................................................................. 13 Quaternary Sea Level Fluctuations ............................................ 14- Pleistocene Holocene Paleochanne! Description ........................................................ 17 Exmore Eastville Cape Charles Regional Pleistocene Formations .......................................... 20 IV. METHODS............................................................................................ 26 Data Collection ......................................................................... 26 Seismic Subbottom Profiling .................................................. 26 Side Scan Sonar Surveying ................................................... 29 Data Reduction ......................................................................... 30 Seismic Interpretation .............................................................. 31 Sediment Samples and Grain Size Analysis ........................ 35 IV Page V. HOLOCENE DEPOSITION................................................................ 38 Sediment Size Distribution ..................................................... 38 Sedimentation Patterns ......................................................... 42 Mobjack Bay Sedimentation ................................................. 43 V I. RESULTS.............................................................................................. 44 Stratigraphy and Mapping of Paleochannels ...................... 44 Channel and Fill Dimensions ................................................ 52 Sedimentation Patterns .......................................................... 56 Sediment Characteristics ....................................................... 63 V II. DISCUSSION...................................................................................... 67 Development of Mobjack Bay andits Paleochannels 67 Application of the Facies Model ............................................ 69 Mobjack Bay facies summary Comparison of seismic facies to end-member examples Modern Sedimentation, Source or Sink ................................ 73 V I I I . SUMMARY and CONCLUSIONS.................................................... 75 IX . FURTHER INVESTIGATIONS............................................................. 78 X. REFERENCES....................................................................................... 79 APPENDIX A. Stratigraphic line drawings of the seismic record for data taken on: 1.) March 1986 2.) June 1992 3.) June 1993 4.) July 1993 5.) July 1994 v LIST OF FIGURES Figure Page 1. Location of Study A re a ..................................................................................... 2 2. Previously mapped Mobjack Bay paleo-drainage channel ........................ 4 3. Diagram of scarps and terraces in northern North Carolina and the coastal plain of Virginia ............................................................................... 5 4. Cross-sectional profile indicating the typical succession of channel deposits during a marine transgression ................................... 7 5A. Distribution of morphology in plan view and sedimentary facies in longitudinal section of an idealized wave-dominated estuary 12 5B. Distribution of morphology in plan view and sedimentary facies in longitudinal section of an idealized tide-dominated estuary ................ 12 6. Sea level curve ................................................................................................. 15 7. Map of the three major Quaternary paleochannel systems ..................... 18 8. Mobjack Bay upland stratigraphy................................................................... 21 9A. Location of Shirley coast ............................................................................. 22 9B. Location of Sedgefield coast ...................................................................... 22 9C. Location of Lynnhaven coast ..................................................................... 22 10. Locations of Middle Peninsula scarps ....................................................... 23 11. Sub-bottom profiling tracklines .................................................................. 27 12. Side Scan sonar trackline .......................................................................... 28 13. Flowchart of seismic interpretation procedure and terminology 32 14. Relations of strata to upper and lower boundaries of a depositional sequence.............................................................................. 34 VI Figure Page 15. Sediment sample locations ................................................................... 36 16A. Nomenclature used in grain size analysis .............................................. 37 16B. Ternary classification of sediment grain size ........................................ 37 17. Isopleth map of total mud contents in the lower bay bottom sediments ..................................................................................... 39 18. Lower Chesapeake Bay distribution of sediment types ......................... 41 19. Location of selected seismic lines used in the text ................................ 46 20. Map of the Late Pleistocene paleochannel system in Mobjack Bay ............................................................................................. 47 21. Seismic line A to A' crosses the middle ofMobjack Bay ...................... 49 22. Seismic line B to B' describes the lateral extent of the Mobjack Bay paleochannel ................................................................... 50 23. Seismic line C to C' is located on the western margin of Mobjack Bay ........................................................................................... 53 24. Seismic line D to D’ shows the paleomorphology of York Spit 54 25. Contour map of the present bathymetry of Mobjack Bay .................. 57 26. North River upper sediment boundary of individual sequences 60 27. Ware River upper sediment boundary of individual sequences 61 28. Severn River upper sediment boundary of individual sequences 62 29. Map of the distribution of sediments