The Middle Miocene Alum Bluff Flora, Liberty County, Florida
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THE MIDDLE MIOCENE ALUM BLUFF FLORA, LIBERTY COUNTY, FLORIDA By SARAH LYNN CORBETT A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2004 For Daddy, who grew up under the shade of a big live oak and taught me the value of all things in nature 01/02/47-10/23/03 The Peace of Wild Things When despair for the world grows in me And I wake in the night at the least sound In fear of what my life and my children’s lives may be, I go and lie down where the wood drake Rests in his beauty on the water, and the great heron feeds. I come into the peace of wild things Who do not tax their lives with forethought Of grief. I come into the presence of still water. And I feel above me the day-blind stars Waiting with their light. For a time I rest in the grace of the world, and am free. -Wendell Berry ACKNOWLEDGMENTS I would like to thank my advisor and committee chair, Dr. Steven R. Manchester, for help with fieldwork, processing samples, examining leaf material critically, and for general advice along the way. I also thank my committee members, Dr. Walter Judd, Dr. David Dilcher, and Dr. Michelle Mack, for reviewing my work and making much needed suggestions. Several other persons and organizations deserve acknowledgment as well. The Nature Conservancy provided a permit for me and others to collect fossil plants on their property, and Greg Seamon of The Nature Conservancy helped to arrange access to the property. The Florida Paleontological Society Gary Morgan Award committee and the Southwest Florida Fossil Club provided monetary support for fieldwork and research. Dr. David Jarzen provided help with identification of some palynomorphs, provided access to modern reference pollen collections and palynological reprints, and made revisions to the pollen section. Student assistant, Sabrina Khouri helped with pollen counts, cuticle extraction, databasing, and photography. Global Geolabs of Medicine Hat, Alberta, Canada, and Russ Harms processed pollen samples and generously processed those samples for free. The University of Florida Electron Microscopy Core Laboratory provided their facilities at no cost, and Fred Bennett and Karen Kelly of the EM lab provided excellent training and technical support. Roger Portell answered ii questions on Alum Bluff geology and reviewed revisions of the geology section. Dr. Jon Bryan and Harley Means offered useful conversations on panhandle geology and allowed me to accompany them on several field trips. Dr. Bill Elsik, Dr. Vaughn Bryant, Dr. John Wrenn, and Dr. Fred Rich shared information and reprints on eastern Miocene palynofloras. J. Yoder, R. Portell, K. Schindler, T. Sweet, S. R. Manchester, T. A. Lott, the 1999 Paleobotany Class, the 2002 Phytogeography Class, and members of the Florida Paleontological Society (2003) collected fossils from Alum Bluff. Laura Corbett McGuire provided her photographic efforts and an occasional push in the right direction. Tamika Robinson offered advice and answered many late night frantic phone calls. Lastly, I would like to recognize my parents. I extend appreciation to my mother, Janice Corbett, for extensive photocopying of references, support through this project and always, and an enormous amount of tolerance and patience. And to my father, the late Richard Larry Corbett, I express deep gratitude for always providing much needed graduate school survival advice, being interested in my work, being attentive to my questions, and instilling the interest in me to begin with. iii TABLE OF CONTENTS ACKNOWLEDGMENTS………………………………………………………… ii LIST OF TABLES……………………………………………………………....... vi LIST OF FIGURES………………………………………………………………. vii ABSTRACT……………………………………………………………………….. ix INTRODUCTION……………………………………………………………….… 1 Modern Flora of Apalachicola Bluffs and Ravines……………………. 2 Geology………………………………………………………………….... 4 MATERIALS AND METHODS………………………………………………….. 8 RESULTS…………………………………………………………………….…… 13 Leaf Macrofossils………………………………………………………… 13 Fruits and Seeds……………………………………………………….… 22 Spores and Pollen……………………………………………………….. 23 Spores…………………………………………………………….. 23 Pollen………..……………………………………………….……. 27 Fungi………………………………………………………………………. 36 DISCUSSION…………………………………………………………………….. 71 Comparison with Other Miocene Floras………………………….……. 71 Paleoecological Implications………………………………….………… 73 Biogeographical Implications…………………………………………… 77 CONCLUSIONS…………………………………………………………….……. 79 APPENDIX A SELECTED WOODY TAXA OCCURRING IN AND AROUND THE APALACHICOLA BLUFFS AND RAVINES AREA AND THEIR TYPICAL HABITATS……………………………………………….…… 82 APPENDIX B EXPLANATION OF PALYNOMORPH TERMINOLOGY…... 85 iv REFERENCES…...……………………………………………………….……… 90 BIOGRAPHICAL SKETCH……………………………………………...……….96 v LIST OF TABLES Table page 1 Examples of historical names of the stratum currently known as the Alum Bluff Group, undifferentiated and their corresponding publication………………………………………………………………… 7 2 Terrestrial Miocene palynomorph localities from eastern North America used for comparison with Alum Bluff palynomorphs………. 24 3 Taxa shared between Alum Bluff and other Miocene localities……... 74 4 Summary of taxa identified at Alum Bluff……………………………… 81 vi LIST OF FIGURES Figure page 1 Map showing Alum Bluff and surrounding area………………………. 38 2 Apalachicola River and Alum Bluff exposure…………………………. 39 3 Alum Bluff exposures showing Pleistocene to Miocene age sediments………………………………………………………….……… 39 4 Lithostratigraphy of Alum Bluff………………………………….………. 40 5 Summary of geochronology, showing temporal relationships between Torreya and Chipola Formations, and the Alum Bluff Group, undifferentiated………………………………………………….. 41 6 Fossil plant strata at the Alum Bluff exposure…………………….…... 42 7 Leaflets of Carya (Juglandaceae)………………………..……….…..... 43 8 Lauraceous leaf ………...……………………………………………….. 44 9 Leaves of Paliurus (Rhamnaceae) .. ………………………..………… 45 10 Leaves and ‘wood’ of Sabalites (Arecaceae)……………………….… 46 11 Graduate student Xin Wang with a very large example of a Sabalites leaf from Alum Bluff…………………………………………... 47 12 Leaves of Ulmus (Ulmaceae) ………………………………………….. 48 13 Alum Bluff leaf Morphotype AB1 ………………………………………. 49 14 Alum Bluff leaf Morphotype AB2 ………………………………………. 50 15 Alum Bluff leaf Morphotype AB3 ………………………………………. 51 16 Alum Bluff leaf Morphotypes AB4, 5, 6, and 7………………………... 53 vii 17 Alum Bluff leaf Morphotypes AB8 and 9 ……………………………… 54 18 Alum Bluff leaf Morphotypes AB10, 11, and 12…………………..…... 55 19 Fruits and seeds from Alum Bluff………………………………………. 56 20 Pie chart showing pollen count summary for Alum Bluff…………….. 57 21 Fern spores from Alum Bluff……………………………………………. 59 22 Gymnosperm and Poaceae type pollen from Alum Bluff……….……. 61 23 Liliaceae, Magnoliaceae type, and miscellaneous dicotyledonous pollen from Alum Bluff………………………………………….………... 63 24 Fagaceae and Ulmaceae pollen from Alum Bluff…………………….. 64 25 Miscellaneous dicotyledonous pollen from Alum Bluff……….………. 66 26 Unknown palynomorphs and dinoflagellate cyst from Alum Bluff…... 68 27 Fungal sporomorphs from Alum Bluff……………………………….…. 70 viii Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science THE MIDDLE MIOCENE ALUM BLUFF FLORA, LIBERTY COUNTY, FLORIDA By Sarah Lynn Corbett December 2004 Chair: Steven R. Manchester Major Department: Botany The Miocene flora of Alum Bluff, Liberty County, Florida, is significant because of the relative rarity of Tertiary, and especially Miocene, fossil plant localities in eastern North America. After conducting a paleofloristic study including leaves, seeds, fruits, and pollen at Alum Bluff, implications for understanding Miocene climate, biogeography, and paleoecology of the region were inferred. The first study of the flora of the Alum Bluff site was conducted on leaf impressions by E.W. Berry in the early twentieth century. Berry studied only leaf macrofossils and identified 12 leaf species. Recent collections and further examination of specimens reveals 22 identified taxa, 7 morphotypes of uncertain taxonomic affinity, and 21 examples of unknown taxonomic affinity are also ix present in the flora. Berry described the flora as being tropical with some temperate elements found in the Florida panhandle today; however, recent finds such as Paliurus, which is extinct in North America but present in Eurasia today, suggest different floristic affinities and indicate that the flora was warm- temperate. The composition of the flora was compared with modern floras and other Miocene floras to determine the environmental conditions present at Alum Bluff in the Miocene. It was found that the Alum Bluff flora an elm-hickory- cabbage palm forest (similar to that of North central Florida today) occurring along a river or near a river delta. Biogeographical implications of the Florida panhandle region during the Miocene were inferred based on the floral composition of Alum Bluff. The use of fruit, seeds, pollen, and leaves increased the known diversity of the Alum Bluff flora, making it a paleobotanically important case. x INTRODUCTION Miocene floras are poorly known in eastern North America. In the southeast U.S., Tertiary paleobotanical deposits are even less common, though there are a number of marine Tertiary deposits in the region. The Brandon lignite flora of Vermont, the Brandywine flora of Maryland, and the Alum Bluff flora of Florida are some examples of the few eastern North American Miocene localities with good preservation