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Reconstruction of late holocene precipitation for Central Florida as derived from isotopes in speleothems

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Title:
Reconstruction of late holocene precipitation for Central Florida as derived from isotopes in speleothems
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Soto, Limaris R
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Paleoclimate
Stalagmites
Stable isotopes
Uranium-series
Teleconnections
Dissertations, Academic -- Geology -- Masters -- USF   ( lcsh )
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government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )

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Summary:
ABSTRACT: Little is known about the paleo-precipitation of the Florida Peninsula. In order to better understand Floridas late Holocene climate variability (last 4,200 years), the isotopic composition was analyzed of four speleothems from two caves, in West-Central Florida. Two speleothems were collected from BRC Cave in Hernando County, and two others from Briar Cave in Marion County. This study represents the first speleothem-based paleoclimate records for Florida. Uranium-series disequilibrium analyses were determined by using thermal ionization mass spectrometry (TIMS) to provide accurate determination of chronology of the deposition of the speleothems.Stable isotopic analyses of oxygen and carbon were performed using stable isotope mass spectrometry, which provided information regarding changing amounts of precipitation (increase in precipitation, decrease in the and#61540;18Oc) and types of vegetation above the cave (increased forest density, decrease in the and#61540;13Cc). Variations in the speleothems and#61540;18O composition reveal abrupt changes in precipitation amount, fluctuations that appear both regional and hemispheric in nature. Strong similarities between the speleothem and#61540;18O, Lake Tulaneand#61472;and#61540;D record (Cross et al. 2003; 2004) and the SE US tree-ring record (surrogate for spring precipitation - Stahle and Cleaveland 1992) suggests a regional atmospheric influence on Floridas precipitation.The major causes of changes in precipitation are proposed to be Atlantic Multi-decadal Oscillation (AMO), El Nino and changes in the relative positions of the Intertropical Convergence Zone (ITCZ)-North Atlantic High (NAH). Comparison between the and#61540;18Oc and surrogates of these influences, show all three have some effect. AMO and El Nino have short-term (decadal) influence and ITCZ-NAH has a long term (centennial) influence. The contributions of these climatic effects have implications for teleconnections involving Floridas climate; the AMO correlation shows higher latitude influence, while El Nino and the ITCZ show tropical influence on subtropical Florida.
Thesis:
Thesis (M.S.)--University of South Florida, 2005.
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Includes bibliographical references.
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by Limaris R. Soto.
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Reconstruction of Late Holocene Prec ipitation for Central Florida as Derived from Isotopes in Speleothems by Limaris R. Soto A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science Department of Geology College of Arts and Sciences University of South Florida Major Professor: Philip van Beynen, Ph.D. Eric A. Oches, Ph.D. H. Leonard Vacher, Ph.D. David Hollander, Ph.D. Date of Approval: November 10, 2005 Keywords: paleoclimate, stalagmites, stable isotopes, uranium-series, teleconnections Copyright 2005 Limaris R. Soto

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Acknowledgements I would like to express my gratitude to the people without whom this thesis would not have been completed. First, I would like to thank my advisor, Dr. Philip van Beynen who continuously supported my work and encouraged me to finish my thesis on time. Next, I would like to thank my thesis committee: Dr. H. Leonard Vacher, Dr. Eric Oches, and Dr. David Hollander for helping to improve my thesis with their thoughtful advice and suggestions. I would like to thank the Departments of Geology and Environmental Science and Policy, Univers ity of South Florida for their help I would like to thank the Karst Rese arch Group, for their useful technical discussions. I would like to thank Lee Flor ea for his willingness to help, insightful discussions, and his help duri ng the sample collection. I woul d like to thank Jason Polk for performing the u-series analysis for this study. I would also like to than k Tom Turner, Robert Brooks, Bill Birdsall and the Red Oak Farms for their help in the sample collection. To my family, I owe a debt of gratitude for their love and support along the path of my academic pursuits. Last but not least, I w ould like to express my deepest gratitude to my husband Luis G. Caldern for his continuous suppor t and encouragement throughout my entire graduate career from the time of application to the time of gradua tion. Without his help, kindness, patience, and mostly his love, I would not have been able to complete this work.

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i Table of Contents List of Tables iii List of Figures iv ABSTRACT vi 1. Introduction 1 1.1. Purpose of Research 1 2. Literature Review 3 2.1. Paleoclimates derived from Speleothems 3 2.2. Oxygen Isotopes 6 2.3. Carbon Isotopes 8 2.4. Isotopic Equilibrium 10 2.5. Dating Techniques 12 2.6. Calcite Deposition Rates 13 2.7. Florida Paleoclimate 15 2.8. Theoretical Interpretation of Stable Isotopes from Florida Speleothems 17 3. Study Area 20 3.1. Geology of the west-central Florida 21 3.2. BRC Cave 23 3.3. Briar Cave 25 4. Methods 28 4.1. Speleothem Analysis 28 4.2. U-series Dating 30 4.3. Stable Isotopes 32 4.4. Rate of Calcite Deposition 33

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ii 5. Results 36 5.1. Uranium-Series Disequilibrium Dating 36 5.2. Calcite Deposition Rates 41 5.3. Stable Isotopic Analysis 46 5.4. Isotopic Equilibrium 55 6. Discussion 57 6.1. Verification of Regional Paleoclimate Signal 57 6.1.1. Speleothems BRIARS04-02 and BRC03-02 58 6.1.2. Lake Tulane and the Speleothems 59 6.1.3. South East Precipitation 60 6.2. Causes of Holocene precip itation change in Florida 62 6.2.1 AMO 62 6.2.2. El Nio (NINO3) 62 6.2.3. Cariaco Basin 64 6.3. Floridas paleoclimate during the last Ice Age 65 6.4. Teleconnections controlling precipitation in Florida 67 7. Conclusions 71 8. References 74 Appendices 82 Appendix A: BRC03-02 Stable Isotopic Results 83 Appendix B: BRC03-03 Stable Isotopic Results 87 Appendix C: BRIARS04-01 Stab le Isotopic Analysis 92 Appendix D: BRIARS04-02 Stab le Isotopic Analysis 96

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iii List of Tables Table 1. Uranium-series dates of stalag mites BRC03-02 and BRC03-03 45 Table 2. Uranium-series dates of stal agmites BRIARS04-01and BRIARS04-02 48 Table 3. Calcite deposition rates for Floridian Speleothems 51

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iv List of Figures Figure 1. Theoretical interpreta tion of stable isotopes fr om Florida speleothems, modified from van Beynen et al. (2004). 19 Figure 2. Research area incl uding location of caves used for paleoclimatic reconstruction of west-central Florida. 21 Figure 3. Florida Hydrologic and Stratig raphic Framework (Modified from Knochenmus and Robinson, 1996), Source: Tihansky and Knochenmus (2001). Both caves in the study are contained within the Ocala Limestone. 23 Figure 4. BRC Cave, showing location of samples and entrance to the cave. 25 Figure 5. Map of Briar Cave, showing locati on of samples and entrance to the cave. 27 Figure 6. BRC Cave samples BRC03-02 and BRC03-03, with location of U-series dates. 29 Figure 7. Briar Cave samples BRIARS04-01 and BRIARSC04-02, with location of U-series dates. 30 Figure 8. Simplified representa tion of frustum fitting. 35 Figure 9. BRC Cave U-series dating results, age vs. depth plot. 38 Figure 10. Briar Cave U-series dating results, age vs. depth plot. 39 Figure 11. Calcite deposition rates for Floridian speleothems. 44 Figure 12. BRC03-03 Interpolation of age at 5.2 ka BP, after 15 ka hiatus. 45 Figure 13. Stable oxygen and carbon isotope records for BRC03-02. 48 Figure 14. Stable oxygen and carbon records for BRC03-03, during the Glacial Period. 49 Figure 15. Stable oxygen and carbon reco rd for BRC03-03, during the Holocene. 51

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v Figure 16. Stable oxygen and carbon is otope records for BRIARS04-01. 53 Figure 17. Stable oxygen and carbon record for BRIARS04-02. 55 Figure 18. Comparison between BRIAR S04-02 and BRIARS04-01, showing isotopic equilibrium for the cave. 56 Figure 19. Correlation between speleothems 18 O of BRIARS04-02 and BRC03-02 18 O records. 58 Figure 20. Comparison between 18 O of BRC03-02 and BRIARS04-02, to D record from Lake Tulane, Florida (Cross et al. 2004). 60 Figure 21. Correlation between 18 O of BRIARS04-02 with the SE US precipitation (Stahle and Cleveland 1 992), as derived from tree-rings. 61 Figure 22. Comparison between 18 O from BRIARS04-02 to NINO3 Index from Cane (2005). The arrows represent match between troughs. 63 Figure 23. Comparison of 18 O from BRC03-02 and BRIARS04-02 to Cariaco Basin Ti% reco rd (Haug et al. 2001). 65 Figure 24. Comparison between the 13 C from BRC03-02 (Glaci al) and the pollen record from Lake Tulane (Grimm et al. 1993). 67 Figure 25. Diagram showing teleconnec tions occurring around Florida; background image NASA/JPL/NIMA. 69

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vi Reconstruction of Late Holocene Prec ipitation for Central Florida as Derived from Isotopes in Speleothem Limaris R. Soto ABSTRACT Little is known about the pa leo-precipitation of the Flor ida Peninsula. In order to better understand Floridas la te Holocene climate variab ility (last 4,200 years), the isotopic composition was analyzed of four speleothems from two caves, in west-central Florida. Two speleothems were collected from BRC Cave in Hernando County, and two others from Briar Cave in Marion County. This study represents the first speleothem-based paleoclimate records for Florida. Uranium-series disequilibrium analyses were determined by using thermal ionization mass spectrometry (TIMS) to provi de accurate determination of chronology of the deposition of the speleothems. Stable isotopic analyses of oxygen and carbon were performed using stable isotope mass spectrome try, which provided information regarding changing amounts of precipitation (increas e in precipitation, decrease in the 18 Oc) and types of vegetation above the cave (incr eased forest density, decrease in the 13 Cc). Variations in the speleothems 18 O composition reveal abrupt changes in precipitation amount, fluctuations that appear both regional and hemi spheric in nature. Strong similarities between the speleothem 18 O, Lake Tulane D record (Cross et al.

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vii 2003; 2004) and the SE US tree-r ing record (surrogate for sp ring precipitation Stahle and Cleaveland 1992) suggests a regional atmospheric influence on Floridas precipitation. The major causes of changes in precipitation are proposed to be Atlantic Multi-decadal Oscillation (AMO), El Nio and changes in the relative positions of the Intertropical Convergence Zone (ITCZ)-N orth Atlantic High (NAH). Comparison between the 18 Oc and surrogates of these influences show all three have some effect. AMO and El Nio have short-term (decadal) influence and ITCZ-NAH has a long term (centennial) influence. The contributions of th ese climatic effects have implications for teleconnections involving Floridas climate; the AMO correlation shows higher latitude influence, while El Nio and the ITCZ show tropical influence on subtropical Florida.

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1 1. Introduction Limestone caves provide a stable environment for the deposition of calcite or aragonite formations, such as stalagmites, st alactites and flowstone (generically termed speleothems ) (White 2004). Through uranium-series di sequilibrium dating and variations in the stable isotopes in calcite, speleoth ems can provide high-reso lution records of the paleoclimate and paleo-vegetation changes above the cave that can be correlated with other paleoclimate records (Schwarcz 1986; Do rale et al. 1992; Harmon et al. 2004). Changes in the oxygen and carbon isotopic composition of speleothems have been studied for many years, providing considerable amount of confidence in speleothems as paleoclimatic records (Dorale et al. 2002). 1.1. Purpose of Research The purpose of this study is to devel op and improve the understanding of the paleoclimate of Florida, with emphasis on whether speleothems can record hydrologic responses to changing atmospheri c circulation patterns that affect the Florida Peninsula. Changes in precipitation over the last 4,200 years, which encompass two abrupt contrasting climate intervals, the Medieval Warm Period (MWP), from 1000 to 1300 AD, and the Little Ice Age (LIA), from 1400 to 1850 AD, can be attributed to changes in atmospheric circulation patterns. Variations in the oscillation of the North Atlantic High

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2 (NAH) (also known as the Bermuda High) as determined by the relative position of the Intertropical Convergence Zone (ITCZ ), the Atlantic Multi-decadal Oscillation (AMO), or variable intensity of El Nio S outhern Oscillation (ENSO), with respect to Florida. The LIA is best known globally for it s cold temperatures in Europe and North America (Grove 1998; OBrien et al. 1995; Hodell et al. 2005). The MWP was characterized by a global increas e in the mean annual temperature compared to modern temperatures, and has been shown in paleoc limate records as diverse as the Caribbean Sea (Haug et al. 2001) and Green land (Bradley et al. 2003). While paleoclimates have been reconstructed using speleo thems from some regions in North America, none have been st udied from Florida, whose climate history has been constructed almost exclusively from la ke records (Cross et al. 2004; Poore et al. 2003). This study presents stable is otope records, from four Holocene stalagmites collected from two caves in Florida, a cave in the Brooksville Ridge (hereafter referred to as BRC Cave) and Briar Cave. The us e of speleothems allows us to create a chronologically accurate, high-resolution paleoclimatic record to test the findings of the few local lake records, such as Lake Tulane in Avon Park, Flor ida (Cross et al. 2004). This record will add ne w information to the existing base of knowledge regarding the paleoclimate of the Florida Peninsula duri ng the late Holocene (last 4,200 years).

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3 2. Literature Review 2.1. Paleoclimates derived from Speleothems Caves are naturally occurring underground voids commonly formed by the dissolution of carbonate bedrock (e.g. White 1988; Ford and Williams 1989) The formation of caves and the di ssolution of limestone is very dependent upon water that infiltrates into the ground and reacts with carbon dioxide from the soil and plants to form a weak carbonic acid. Caves are useful for the study of paleoclim ate because they have stable internal climatic conditions, where the cave temperature exhibits little variation during the year, with its thermostat set at mean annual su rface temperature. Speleothems found in caves have variable stable isotope ratios, whic h provide information on past temperatures, precipitation and vegetation. Caves are protected from destruction by surface processes, and by using U-series analysis precise dating of speleothems can be obtained. This dating technique combined with speleothem-derived high-resolution variati ons in the ratios of 18 O/ 16 O and 13 C/ 12 C allow the interpretation of su rface environmental changes over hundreds of thousands of years. Surface temp eratures can be reconstructed using oxygen isotopes from the calcite and fluid inclusions trapped within the crys tals (Harmon et al. 2004). Oxygen isotopes can provide indirect measures of the amount of precipitation falling over the cave (Lachniet et al. 2004). The carbon isotope record in

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4 speleothems is a function of the vegetation de nsity, the types of plants growing above the cave, (Dorale et al. 1992; van Beynen et al. 2004) and biological activity in overlying soils (White 2004). Speleothems are formed as part of the me teoric water cycle. Variations in their composition, and growth rate reflect environm ental changes above the cave (Lauritzen and Lundberg 1999a). Speleothems consist of calcium carbonate (CaCO 3 ) precipitated from cave drip waters that are supersaturat ed with respect to calcite or aragonite. Supersaturation is achieved by the degassing of carbon dioxide from drip waters, which enter the cave through fractures. Degassing o ccurs because the water was previously equilibrated with CO 2 at high partial pressure in the soil percolation zone and degasses upon emergence into the lower P CO2 of the cave gallery (e .g. Lauritzen and Lundberg 1999a). After degassing, preci pitation of calcium carbona te occurs, forming the speleothem. Speleothems forming under condi tions of high humidity ~100% and gradual degassing of CO 2 are commonly found to be in oxygen isotopic equilibrium with the drip water from which they grow (Hendy 1971; Frum kin et al. 1994). In coastal areas, the 18 O of precipitation has a order of magnitude greater effect on the 18 Oc compared to the temperature dependence of the 18 O fractionation between cave seepage water and speleothem calcite, and the changing composition of the 18 O of sea water (Harmon et al. 2004).

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5 In addition to stable isotopes speleoth ems contain other components that can serve as other climate proxies, e.g. pollen (B astin 1978; Lauritzen et al.1990; Burney et al. 1994., Linge et al. 2001), organic matter (van Beynen et al. 2000), trace elements (Gayscone 1983; Goede and Vogel 1992; Robe rts et al. 1998; Linge et al. 2001) and annual growth laminae (Baker et al. 1993; Shopov et al. 1994; Genty and Quinif 1996; Lauritzen and Onac 1999). During the past four decades, most paleoc limatological studies have concentrated either on the marine sediments or ice cores. Recent efforts in reconstructing climate change from continental records have develope d new interest in speleothems as climatic surrogates (e.g., Hendy 1971; Schwarcz 1986; Ga yscone 1992; Bar-Matthews et al. 2000; Kolodny et al. 2003). The increased interest in speleothems has come from: 1) different isotopes of hydrologic and clim atic processes incorporated into the calcite of the speleothem; 2) the advances made into unders tanding the paleoclimatic meaning of these isotopes combined with advan ces in thermal ionization ma ss spectrometry (Musgrove et al. 2001; Mickler et al. 2004) and 3) the extensive geographi c presence of speleothems in different latitudes, which can be a limiting fa ctor for other proxy records (Mickler et al. 2004).

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6 Vaks et al. (2003) used U-se ries dating and stable isotop es to reveal changes in the isotopic composition of the speleothem, whic h suggested changes in the nature of rain shadow aridity during glacial a nd interglacial intervals. In China, changes in the Asian monsoon were recorded in the 18 O isotopic signal of a stalag mite (Zhang et al. 2004), with changes in the Asian monsoon during th e Holocene causing periods of warmer and then cooler conditions for the area. Fleitm ann et al. (2003) used a stalagmite from southern Oman, and found that the 18 O isotopic signal was reco rding changes in the amount of monsoon precipitation. 2.2. Oxygen Isotopes As calcite is being deposited in the cave to form a speleothem, a temperaturedependent fractionation occurs (Kim and ONeil 1997), and the stalagmite reflects a combination of composition of seepage water and precipitation (Gayscone 1992; Lauritzen and Lundberg 1999). When deposited under conditions of isotopic equilibrium, variations in the values from speleothems can incorporate all the information for paleoclimate reconstruction as complex as any other archive of meteoric water variations, such as ice co res (Dorale et al. 2002). In Florida, the isotopic composition of the precipitation fallin g above the cave is affected by different effects. The c ontinental effect occurs when low pressure systems move across continents a nd preferential loss of 18 O occurs, producing isotopically depleted precipitation (Craig 1961). The o cean temperature effect represents the

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7 fractionation between liquid and vapor phase at the source of the atmospheric moisture (Dorale et al. 2002), changes in ocean temp erature during different seasons cause changes in the isotopic composition of the water evaporated from the ocean (Ingraham 1998). Ocean temperature plays a major role in the Florida Peninsul a, because of the location with respect to the Gulf of Mexico and the Atlantic Ocean. The amount effect represents the relation between precipitation 18 O values and some climatic parameters such as temperature and the intensity of rainfall (Dansgaard 1964). The intensity of rainfall is dependent by the size of the st orms, and larger thunderstorms, common in Floridian summers, produce a more depleted precipitation than smaller storms (Gremillion and Wanielista 2000). The s torm track effect variations in storm tracks are due to changes in atmospheric circulation. Th e isotopic signal of pr ecipitation can change if there is a variation of around 10 north or south from the location of the storm (Dansgaard 1964). In different parts of the globe this effect will be controlled by monsoons, in Florida changes in atmospheric circulation, like the North Atlantic High will affect the isotopic composition of the rain. The isotopic composition of the water as it infiltrates in the cave is also going to be affected by different effects The e vaporation effect which can be caused by (a) water pooling at the surface, leads to fractionation of the residual water, (b) by the evaporation of wate r flowing into the cave with low relative humidity (below ~ 90%), or (c) by rapid air movement (Wigley and Brown 1976). The m ixing effect represents the combination of different wa ters, which leads to the removal of the seasonal isotopic signal of the water (Yonge et al. 1985). The r echarge effect represents the restriction of recharge to partic ular seasons, (Jones et al. 2000). The c ave temperature

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8 effect, represents the isotopic fractionation betw een water and calcite during calcite deposition (Lauritzen and Lundberg 1999a), the temperature dependence of the fractionation has been determined as ~ 0.24 /C (Friedman and ONeil 1977; Schwarcz 1986; van Beynen et al. 2004). 2.3. Carbon Isotopes Carbon has two naturally-occurring isotopes, 12 C and 13 C. The carbon isotopic signal in speleothem calcite initiates from the 13 C/ 12 C ratio of dissolved inorganic carbon (DIC) in the drip water (Dorale et al. 1998; Harmon et al. 2004). The dissolved carbon species in cave waters are derived from soil CO 2 and cave carbonate bedrock (Turi 1986; Dorale et al. 1992). The isotopic composition of the C values is affected by different factors, the dissolution of carbonate bedrock, the CO 2 created by plant respiration and the decomposition of the organic matter in the soil (Hendy 1971; Dennist on et al. 2000). In temperate climates, soil CO 2 is produced largely by the decomposition of organic matter and by plant root respiration (soil respiration), and the C composition of soil CO 2 is related to the type of vege tation growing above the cave at the time the calcite in the speleothem was deposited. Soil seep age waters obtain their initial C signatures from soil CO 2 and are modified when carbonate bedrock is dissolved as the water infiltrates to the caves. Changes in the C composition of cave seepage waters are controlled by changes in the C composition of soil CO 2 (Dorale et al. 1992). For example, if there is herbaceous vegetation above the cave, this mi ght give an indication of dry conditions.

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9 The C composition is interpreted as reflec ting changes in the composition of C 3 and C 4 plants on the surface and above the cave. Differences in the C values of speleothems results from varying contributions of carbon originally derived from plants utilizing the C 3 and C 4 photosynthetic pathways (Doral e et al. 1992, 2002). There is a bimodal distribution in the 13 C values of terrestrial plants resulting from differences in the photosynthetic reaction utilized by the plant. Most terrestrial plants are C 3 plants and have 13 C values ranging from -24 to -34. C 4 plants composed of aquatic plants, desert plants, salt marsh plants a nd tropical grasses, have 13 C values ranging from -6 to -19 (Deines 1980). A higher proportion of C 4 plants is interpreted as drier environmental conditions with an abundance of grasses. C 3 plants are interpreted as forest vegetation, mostly trees, shrubs and forbs with plants th at are better adapted to moister environments. Changes in the C 3 and C 4 pathways is an important factor in understanding paleoclimate, because it provides evidence for the precipitation in the region that controls the type of vegetation above the cave. Evidence for changes in the stalagmite C comes from a study by Dorale et al. (1998) that showed changes in th e vegetation above the cave. The C record provided evidence of changes from forest to sava nnah to prairie and back to forest. The speleothem grew from 75 to 25 ka, maximu m temperatures were recorded around 59 to 55 ka, dominated by prairie vegetation as recorded by the C values. A study by van Beynen et al. (2004) using a stalagmite from New York, provided evidence that the C recorded changes in the density of the forest. The C record showed that forests

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10 (C 3 vegetation) have been the predominant vegetation above the cave, although other changes in vegetation were recorded by the speleothem. The 13 C values of stalagmites reflect the variable sources of carbon, mainly from the soil CO 2 derived from vegetation. The fracti onation process from dissolved CO 2 in the soil to aqueous CO 2 to HCO 3 -1 to CO 3 -2 to solid CaCO 3 results in calcite that is enriched in 13 C by about 10 relative to CO 2 under equilibrium conditions (Hendy 1971, Dorale et al. 2002). Temperature change has a relatively sma ll effect on fractionation between the bicarbonate and calcite, in places where soil biogenic activity is the dominant control in the speleothems 13 C calcite record (Deines et al. 1974). Change in temperature causes fractionation in the carbon isotopes during the deposition of calcite from its ambient waters. A 1C in temperature during calcite precipitation causes a shift in the 13 C of 0.125 (Faure 1986): such a shift does not co ntribute greatly to the carbon isotopic signal of our speleothem. 2.4. Isotopic Equilibrium In order to determine the appropriateness of using stable isotopic records for paleo-hydrological paleoclimate reconstruc tions, the isotopic equilibrium of calcite precipitation with ambient waters must be ensured, which usually requires slow CO 2 degassing during calcite precipitation (La bonne et al. 2002). Fluctuations in O along the growth axis of a speleothem reflect a combination of two factors: the temperaturedependent calcite-water fractionatio n and temporal change in the 18 O/ 16 O ratio of the cave

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11 seepage water, which is a complicated and va riable function of th e history of seepage water from its seawater source through its transit within the meteoric water cycle to a cave (Harmon et al. 2004). Stable isotope variations provide tem poral records possessing the potential to yield very important and perh aps unique information a bout past terrestrial climate. Though significant problems may be associated with the inte rpretation of change in the 18 O/ 16 O and 13 C/ 12 C ratios of the cave-deposited cal cite (Harmon et al. 2004). For example, in South Dakota, Serefiddin et al. (2004) used differences in the 18 O isotopic signal of speleothems from the same cave to show that drip site s in a cave may respond differently to climate change. To test whether the speleothem calcite wa s deposited in isotop ic equilibrium with ambient waters, Hendy (1971) proposed that a se ries of samples from the same growth layer were analyzed, from the center of the speleothems towards the sides (Dorale et al. 2002). If the speleothem is deposited under equilibrium conditions, the Hendy criteria required no correlation between the and C of samples collected along the same growth layer, and that does not change more than 0.8 along the growth layer (Hendy and Wilson 1968; Gayscone 1992; van Beynen et al. 2004). If kinetic fractionation occurred during precipitation, and C will be correlated and the isotopic signal corrupted (Lau ritzen and Onac 1999). The problem that arises from testing the Hendy criteria comes from the changes in morphology of the stalagmite. The growth layer is usually thickest al ong the top of the stalagmite, but it decreases and becomes thinner along the sides. When sampling calcite for this test, cross contamination between growth layers can occur, and a negative resu lt of a Hendy Test does not always indicate kinetic fractionation or evapor ation (Lauritzen and Lundberg, 1999a; Dorale et al. 2002).

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12 2.5. Dating Techniques Initial attempts to obtain chronological information from speleothems using uranium-series disequilibrium were first applied by (Rosho lt and Antal 1962; Cherdyntse et al. 1965; Richards and Dora le 2003). The precision of U-series dating has improved greatly over the last few decades, and its application is increasing. Thompson et al. (1974) set forth the fo llowing criteria to accurately obtain Useries dates from speleothems: (1) The sample must contain sufficient uranium; (2) there must be negligible amounts of detrital 230 Th present in the sample; and (3) the sample must not have undergone dissolution and recrysta llization (i.e. formed in a closed system) (White 2004). Adjustments using isochrones can be made for a sample with high amounts of detrital 230 Th in bulk carbonate material (Richa rds and Dorale 2003). Many studies have demonstrated that the speleothems provi de reliable chronologies using the U-series method (Frumkin et al. 1999; Frumkin and Stein 2004). Uranium possesses two isotopes, 235 U and 238 U, which decay to isotopes of Pb through a number of intermediate, radioactive isotopes, some of whose half-lives are of geological magnitude (10 3 10 5 yrs). Therefore, some geological deposits ca n be dated by measuring the degree to which intermediate isotopes have reached radioactive equilibrium with their parents (Schwarz 1986). Carbon-14 is also used in speleothem da ting, but is not as accurate as the U/Th. Dating by the natural decay of 14 C is a well-established technique for carbon-bearing materials with ages less than 50,000 years. The CO 2 extracted from the soil by infiltrating groundwater is derived from the atmosphere a nd from biological processes in the soil so it should be composed mainly of young carbon. The carbon derived from the limestone is

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13 old carbon, with no residual 14 C. In the absence of any isot ope exchange, the carbon that is deposited in speleothems should be 50% old carbon and 50% young carbon (White 2004). In reality there is extensive isotope exchange during the complex process of dissolution, transport and re-de position. It appears that sp eleothems contain about 85% young carbon (Hennig et al. 1983; White 2004), making the use of this dating method highly problematic. U-series dating has advantages over 14 Cdating because it yields calendar years, spans over a longer time pe riod (600,000 years) and is unaffected by the dead carbon problems associated with 14 C dating 2.6. Calcite Deposition Rates Calcite deposition rates, also known as growth rates of speleothems, can provide information about paleoclimatic vari ations, including preci pitation, temperature, and soil activity above a cave (Kaufmann and Dreybrodt 2004; White 2004). The rate of speleothem deposition is determined by soil ca rbon dioxide concentration, drip rate, and temperature, all of which are climate related a nd can affect the rate and shape of growth (Dreybrodt 1999). Hiatuses in a speleothem can indicate periods of climate change that include glacial periods, droughts, and changes in the hydrologic pattern of water flow, and can be used as paleoclimatic indicators. Faster growth rates can be indicative of a warmer, wetter climate in the area, while slow er growth rates can re sult from cooler, drier conditions above the cave (Hennig et al. 1983; van Beynen et al. 2004). The recognition and definition of annual de position layers in thin sections can be difficult, particularly for speleothems that consist of a small nu mber of microscopic

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14 single crystals of calcium car bonate, or high contents of organic matter (Harmon et al. 2004). Deposition layers in speleothems can pi nch, swell and merge, making stratigraphic correlation difficult (Harmon et al. 2004). Even the smallest deviation from the growth layer can produce inaccurate results. The deposition rate mechanisms of stalagmites have been studied for over 30 years. Early investigations include the work by Franke ( 1965), who demonstrated how stalagmite shapes vary due to the deposition process, assuming that increased drip rate leads to an increase in speleothem diameter. Curl (1973) presented a theory to explain the existence of minimum-diameter stalagmites, sh owing that they have two growth regimes, a rapid regime which is dependent on the flow rate and a slow regime independent of the flow rate. Wolfgang Dreybrodt has undertaken a number of studies (Buhmann and Dreybrodt 1985; Dreybrodt and Buhmann 1991; Dreybrodt et al. 1996; Dreybrodt et al.1997, Dreybrodt 1999) where he and others presented the physical and chemical processes for calcite precipitation, and derived a mathematical model describing stalagmite growth (Kaufmann and Dreybr odt 2004). Buhmann and Dreybrodt (1985) were able to create a theoretical model for predicting calcite precipitation to estimate the rate of growth from laminar or turbulen t-flowing water, covering the surface of the speleothem (Dreybrodt 1999). Their model take s into account three processes occurring during calcite deposition, the chemical reac tion at the calcite-so lution interface, the diffusional transport of species through the solution to the surface of the solid, and the last is the slow conversion of carbon dioxide into protons and carbonate ions (Baker and Smart 1995).

PAGE 24

15 Experimental investigations have shown that these theoretical models provide precipitation rates that are generally relia ble, and can be used for interpreting paleoclimatic records (Dreybrodt et al. 1996, Liu and Dreybrodt 1996; Dreybrdot 1999). Baker et al. (1998) measured the annual laminae thickness of stalagmites that had previously been dated by U-series TIMS and compared the annua l deposition rates to theoretically predicted calcite precipitation rates. Even though their results showed an agreement between the measured and theoretic al values, complications arise because of calcite porosity and the cessation of water feeding the stalagmite. With recent improvement of U-series mass spectrometr y, dating can be obtained with smaller amounts of calcite, leading to more accurate calculations of mean deposition rate along speleothem growth axes (Dor ale et al. 1998; Linge et al. 2001; Serefiddin et al. 2004). 2.7. Florida Paleoclimate Previous paleoclimate research in Florida has included the use of lake sediments. These lake deposits reveal that most of Fl oridas shallow modern lakes were dry during the early Holocene, due to a lower water ta ble (Watts and Stuiver 1980; Filley et al. 2001). Mud Lake in Florida is one of the sinkhole lakes studied in the area. C values from this lake, recorded changes in the wa ter table and precipitati on during the Holocene, with increased lake levels at 8.5 5.0 ka 14 C yr BP and again at 2.5 ka 14 C BP (Filley et al. 2001). Liu and Fearn (2000) studied sediment co res from Western Lake, Florida, and provided a 70,000-year record of coastal environmental changes and catastrophic

PAGE 25

16 hurricane landfalls along Florid as Panhandle. During 5-3.4 ka 14 C yr BP, dry conditions were observed, while wetter conditions were found during a hyperactive period from 3.4 to 1.0 ka 14 C yr BP. The climatic events were probably controlled by shifts in the position of the Jet Stream and the Nort h Atlantic High (Liu and Fearn 2000). Little Salt Spring, another sinkhole lake lo cated in west central Florida (Alvarez et al. 2005) yielded O and C records over the last ~12.0 ka, which the authors suggest models the paleo-hydrological record of the area. The data showed abrupt changes during the Late Holocene (2.7 and 2.0 ka BP) characterized by low O values, followed by an increase in the O values at around 1.1 ka and 900 years BP. These low values were interpreted as i ndicators of dry climatic cond itions, while the more-enriched isotopic values were interpreted as wette r conditions, characterized by a sea-level highstand (Alvarez et al. 2005). Lake Tulane is the most investigated la ke in Florida for th e reconstruction of paleoclimate (Grimm et al. 1993; Watts a nd Hansen 1994; Cross et al. 2004). Pollen extracted from the lake sediments indicate major vegetation shifts dur ing the last glacial cycle which correlated with changes in icerafted lithic sediments (Heinrich events) found in marine sediment cores from the Nort h Atlantic. The rapid vegetation shifts in Florida correlate with melt water discharges fr om the Great Lakes Region to the Gulf of Mexico via the Mississippi Rive r (Grimm et al. 1993). Lake Tu lane has also been studied by Cross and others (2004), their sedimentar y record represents the last 80,000-years. Their investigation suggested that the cha nges in the deuterium/hydrogen (D/H) isotopic composition of algal and terrestrial organic material is directly li nked to the hydrologic cycle, and its variability at th e bulk and molecular le vels has the potential to be used as a

PAGE 26

17 proxy for paleoclimatic and paleohy drologic reconstructions. Greater D values appear to be caused by a decrease in the rela tive humidity of the atmosphere. 2.8. Theoretical Interpretation of Stab le Isotopes from Florida Speleothems Before being able to interpret the paleoclimate meaning of the stable isotopes from a speleothem, the main influence generating that signal has to be determined. The two dominant factors are precip itation and temperature. Speleothem records from regions that have a predominance of thunderstormsderived precipitation all suggest that precipitation is the dominant factor influencing 8 Oc (Fleitmann et al. 2003, Holmgren et al. 1999; Lachniet et al 2002). Figure 1 shows the re lationship between the oxygen isotopic composition and its amount. During warmer conditions an increase in thunderstorms will produce higher precipitation fo r the area. Larger storms have stronger convection, therefore creating precipitation at higher alti tudes. Consequently, the resultant precipitation will be isotopically depleted which is directly related to precipitation amount. During cooler conditions, pr ecipitation will decrease in the area and thunderstorms will form at lower altitudes. Consequently, the resultant precipitation will be isotopically enriched. Evidence of the relationship between is otopic composition and amount of rainfall has been shown by the study by Lachniet et al (2004). They studied the effects of El Nio/Southern Oscillation (ENSO) for the Isthmus of Panama using speleothems. They observed in a calibration study a negative co rrelation between t hunderstorm-derived precipitation amount and the rainfalls 18 O composition, and used that result to state that

PAGE 27

18 their 18 O variations in tropical speleothems wa s an indicator of precipitation amount. Their study provides an app licable interpretation of 18 O variations for sub-tropical areas like Florida, where thunderstorms provide most of the precipitation to the region. Changes in atmospheric circulation patte rns relative to Florida will affect the amount of moist air flowing into the Pe ninsula and consequently the amount of precipitation. This warm moist air can be directed into Florida from the Equatorial Pacific (during El Nio events Cane 2005), from th e Atlantic (during wa rm Atlantic Multidecadal Oscillations Stahle and Clea veland 1992) and with migration of the Intertropical Convergence Zone (ITCZ Haug et al. 2001). Increases in warm moist air would increase convective processes in the atmosphere, leading to bigger thunderstorms and a higher condensation line in the thunderhea ds shown as in Figure 1 (Fleitmann et al. 2003, Lachniet et al. 2002).

PAGE 28

Figure 1. Theoretical interpretation of stable isotopes from Florida speleothems, modified from van Beynen et al. (2004). 19

PAGE 29

20 3. Study Area Florida is a highly karstifie d carbonate platform, characte rized by the presence of sinkholes, caves, closed depr essions and flooded conduits. These features are well developed because fluctuations in sea leve l have alternately flooded and exposed the carbonate platform, thereby allowing weatheri ng and dissolution processes to occur. The study area consists of two caves, BRC Cave in Hernando County and Briar Cave in Marion County (Figure 1). The adva ntage of caves as repositories of paleoenvironmental information is the great stability of climatic conditions within the cave. Whereas the entrance regions of caves typically undergo climatic fluctuations due to dayto-day meteorological fluctuations, the i nner passages of most caves have air temperatures with little va riations (Schwarcz 1986). BRC Ca ve and Briar Cave both have only one entrance, which create a very stable climatic condition for the cave, reducing evaporative fractionation.

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Figure 2. Research area including location of caves used for paleoclimatic reconstruction of west-central Florida. 3.1. Geology of the west-central Florida The Brooksville Ridge section of the Ocala Arch contains sinkholes, dry karst valleys, and interfluvial hills (Reeder and Brinkmann 1998). There are few surface streams in the region, and drainage is typically through sinkholes and direct infiltration into the artesian Floridan Aquifer, which supplies considerable groundwater to south 21

PAGE 31

22 Georgia and Florida (Miller 1986). Surface eleva tions in the region range from six meters at the bottom of deep sinkholes to 45 meters at the top of the tall est residual limestone hills. Hydrologic and stratigraphic uni ts of west-central Florida are shown in Figure 3 (Tihansky and Knochenmus 2001). The geology in the region is dominated by a series of carbonate units that include Oligocene Suwa nnee Limestone, which ranges from a lightgray to a yellowish-gray packstone and grainstone. The Suwannee Limestone is unconformably overlain by the clay-rich Hawt horn Formation in some parts of the region, and it unconformably overlies Eocene Oc ala Limestone in parts of the region as well (Yon and Hendry 1972; Florea et al. 2003). Pleistocene marine quartz sands overlie the Suwannee Limestone in most of the regi on. The unconformities that exist above and below the Suwannee Limestone represent erosion surfaces, probably formed during emergent periods before and after depos ition (Vernon 1951; Randazzo and Jones 1997). Elevation of the Suwannee Limestone ranges fr om 80 ft below to 132 ft above sea level (Tihansky and Knochenmus 2001). The Ocala Limestone consists of white to light-gray to light-orange limestone with a diverse fossil assemblage the lithology of this formation ranges from variably chalky wackestone or packstone (Tihansky and Knochenmus 2001). The sediments of the Ocala Limestone form one of the most perm eable zones within the Floridian aquifer system. The extensive development of s econdary porosity by dissolution has greatly enhanced the permeability, especially in those areas where the confining beds are breached or absent (Maddox et al. 1991). The Ocala Limestone is typically bounded by

PAGE 32

unconformities. Elevation of the formation range from land surface to 285 ft below sea level (Tihansky and Knochenmus 2001). Figure 3. Florida Hydrologic and Stratigraphic Framework (Modified from Knochenmus and Robinson, 1996), Source: Tihansky and Knochenmus (2001). Both caves in the study are contained within the Ocala Limestone. 3.2. BRC Cave The BRC Cave is one of the longest dry caves in Florida, ~ 1 km in length with only one humanly-constructed entrance, which means the cave atmosphere lacks rapid airflow, thereby preventing evaporative fractionation. The entrance of the cave is located 23

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24 in a very small approximately 70-year-old quarry, 9 meters in diameter and around 4 meters deep (Figure 4 ). Essentially, the cav e has one level interrupted by considerable breakdown (Florea pers. comm. 2004). BRC Cave is formed within the Ocala Limestone. The caves of the Brooksville Ridge are formed by structural and chemical processes. The vegetation above the cave is characterized as hardwood hammocks populated by oak, hickory and maples (Armstrong et al. 2003). Speleothems BRC03-02 and BRC0303 were collected from two different sections in BRC Cave (Figure 4). Florida is characterized by its humid subtropical climate and high rainfall. Rainfall patterns are primarily driven by adjacent sea surface temperatures and atmospheric convection (Watts and Hansen 1994). The average temperature of the Brooksville Ridge area is 21.3 C, and the average annual precipitation is 1356 mm (South East Regional Climate Center). Th e maximum monthly mean temperature of 27.6 o C occurs in August, and the minimum monthly mean temperature of 13.6 o C occurs in January. The maximum monthly mean precipitation volume of 219 mm occurs in August, and the minimum monthly mean of 48.8 mm occurs in October.

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Figure 4. BRC Cave, showing location of samples and entrance to the cave. 3.3. Briar Cave Briar Cave is located on the southern outskirts of Ocala. The cave underlies a low hill between two sinkholes. Briar Cave trends NE-SW and consists of a dry upper level and a partially flooded lower passage (Florea et al. 2003). The cave is approximately 1 km long, making it one of the longest sub-aerial caves in the state of Florida, with only one entrance which reduces evaporative fractionation (Figure 5). Speleothem samples BRIARS04-01 and BRIARS04-02 were collected from the same area of the cave (Figure 5). 25

PAGE 35

26 The cave is formed in the Ocala Li mestone. Hawthorn Group sediments and younger undifferentiated deposits unconformably overlie the Ocala Limestone in the area (Florea et al. 2003). These sedimentary depos its are composed primarily of terrigenous quartz sand and clay with small amounts of limestone, phosphate, and organics (Scott 1988). Locally, the Ocala Group is a fossiliferous shallow marine limestone. It varies in thickness and dips toward the s outh and east in the Briar Cave area, reflecting its position on the flank of the Ocala uplift. The vegetation in the vicinity of the ca ve is characterized by hardwood species, such as oak. The average temperature of Ma rion County is 22 C, and the average total precipitation is 1330 mm per year (South East Regional Climate Center).

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Figure 5. Map of Briar Cave, showing location of samples and entrance to the cave. 27

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28 4. Methods 4.1. Speleothem Analysis Four speleothems, collected from the two caves in west-central Florida to provide a detailed record of late Holocene paleocli mate. Two speleothems were collected from BRC Cave, Hernando County. The collected spel eothems are identified as BRC03-02 and BRC03-03 (Figure 6 ). Upon collection, each stalagmite was sawed vertically along its growth axes and polished to clarify the pos itioning of the laminae. To protect the speleothems from breaking, some of the samples were embe dded in plaster-of -paris creating a cast for the sample. Calcite samp les (30-60 g) were drilled using a dental drillbit in a Dremel tool at 1mm intervals along the apex of the la minae, up the growth axes. BRC03-02 is a stalagmite 21.5 cm in lengt h. Eight samples were collected for Useries dating, and 152 samples were collected for stable isotopes. BRC03-03 is 19.5 cm in length. Nine samples were collected for U-series dating, and 188 samples were collected fo r stable isotopic analysis.

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Figure 6. BRC Cave samples BRC03-02 and BRC03-03, with location of U-series dates. Two other samples were collected from Briar Cave, Marion County. The samples were identified as BRIARS04-01 and BRIARS04-02 (Figure 7). BRIAR04-01 is 15 cm in length. Seven samples were analyzed for U-series, and 140 samples for stable isotopes. BRIAR04-02 is 28 cm in length. Ten samples were collected for U-series and 277 samples for stable isotopic analysis. 29

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Figure 7. Briar Cave samples BRIARS04-01 and BRIARSC04-02, with location of U-series dates. 4.2. U-series Dating Uranium-series disequilibrium dating can be performed on speleothems, provided that sufficient U is present (> 0.02 ppm) and that the system was initially free from non-authigenic 230 Th, as monitored with the 230 Th/ 232 Th index (Latham and Schwarcz 1992; Lauritzen and Onac 1999). Samples from the collected speleothems were analyzed on the 30

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31 thermal ionization mass spectrometer (TIMS), by Jason Polk at the Radiogenic Laboratory at the University of New Mexico under the supervision of Drs. Yemane Asmerom and Victor Polyak. For U-series analyses, 200 to 300 mg of calcite were collected at intervals along the growth axes of the speleothems. The U-series method chronology is a well-established technique in the laboratory at the University of New Mexico (e.g. Denniston et al. 1999; Polyak and Asmerom 2001). Stalagmite calcite powder (~200 mg) is dissolved in HNO 3 and spiked with a mixture of 229 Th233 U236 U. The use of a mixed spike eliminates propagation of weighing error unto the age uncertainties. U and Th are co-precipitated with pure FeOH 3 and subsequently separated on anion exchange columns and purified further on a second column. U and Th are measured on a Micromass Sector 54 thermal ionization mass spectrometer with a high-abundan ce sensitivity filter (Lachniet et al. 2004). All isotopes of interest are measured on an ion-counting Daly multiplier with abundance sensitivity in the range of 20 ppb at one mass distance in the mass range of U and Th, requiring very little background correction even for samples with large 232 Th content. Multiplier dark noise is about 0.12 counts per second. U isotopic standards, such as NBL-112, are measured during the measurements of samples. Typical analytical uncer tainties are in the range of 0.2% for U isotope composition, with similar or somewhat lower precision for Th, depending on the age and size of the sample measured. Age uncertainties include uncer tainties related to initial 230 Th/ 232 Th correction. For example, a 1000-yr-old sample with 0.5 ppm U and 234 U of 1000, should contain about 390x10 6 atoms of 230 Th. Assuming a realistic i onization efficiency of 4x10 -4 and that 65% of the ionized atoms are counted (allowing for counting 229 Th, baselines and

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32 counting housekeeping), the theoretical 2counting statistics precision for this sample is about 0.2%. The realistic errors are higher. The contribution of th e uncertainty in the initial 230 Th/ 232 Th depends on the U/Th ratio and the age of the sample. The significance of the unsupported 230 Th (detrital 230 Th) diminishes with age, but can be significant for young samples with low U/Th ratios. In many studies the correction is done by subtracting an amount of 230 Th that corresponds to the 230 Th/ 232 Th ratio of a component with bulk crust 232 Th/ 238 U value of ~ 3.8 and assuming the component was in secular equilibrium. In this case the 230 Th/ 232 Th ratio, 238 /( 230 x3.8), is ~ 4.4x10 -6 4.3. Stable Isotopes Calcite samples (60-100 g) were drilled using a dental drillbit in a Dremel tool at 1-mm intervals at the apex of laminae along the speleothem growth axes. Some of the speleothems were also sampled by using a co mputer-controlled dri lling stage and drill mount. Upon collection, the samples were weighed (35-80 g) using a Mettler Toledo Analytical Balance. The samples were then analyzed for their oxygen and carbon isotope using mass spectrometry in the College of Marine Science, Stable Isotopic facility at the University of South Florida, St Pe tersburg Campus. The stable isotopes 16 O, 18 O, 12 C and 13 C are measured by reacting th e calcite samples with anhydrous phosphoric acid at 70 C in individual reaction vesse ls of a Keil III carbonate-extr action system coupled to a ThermoFinnigan DeltaPlus XL mass spectrometer. Precision ( ) was monitored by daily analyses of the NBS-19 standa rd and was <0.1 for both oxygen and carbon.

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33 Values are then reported in standard notation relative to Vienna Peedee Belemnite (VPDB). The VPDB was created to eliminate possible confusion in the reporting of isotopic abundances on non-corresponding scales, by th e Commission on Atomic Weights and Isotopic Abundances at the 37 th General Assembly at Lisbon, Portugal. They recommended that the 13 C 12 C relative ratios of all substa nces be expressed relative to VPDB (Coplen 1994). These analyses provided data on changing precipitation amounts ( 18 O) and shifts in vegetati on composition above the cave ( 13 C). 4.4. Rate of Calcite Deposition The rate of calcite deposition of a spel eothem is a function of super-saturation (P CO2 ) and drip rate (rainfall) (B aker et al. 1998). The thic kness of annual growth bands in stalagmites is frequently used as su rrogate for surface precipitation, because band thickness is controlled by the drip rate, which is controlled by the amount of rainfall above the cave (Baker et al. 1993; Genty and Quinif 1996; Holmgren et al. 1999; Qin et al. 1999). Stalagmite deposition rates are correlate d to temperature and the amount of carbon dioxide available in th e soil, while the amount of precipitation controls the stalagmite diameter (Kaufmann and Dreybrodt 2004).The determination of speleothem deposition rates has evolved to a high level of accuracy due to ra diogenic dating methods, such as U-series TIMS mass spectrometry. Through the use of accurate U/Th dates spaced along speleothem growth axes, deposition rates can be calculated with high precision, providing evidence of hiatuses (Dreybrodt 1999).

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Annual rates for the samples were previously calculated by dividing the portion of calcite (mm) by the number of years over which that portion was deposited as derived from Th/U age estimates (van Beynen et al. 2004). This applied method for measuring deposition rates did not take in account the changing shape and width of the speleothem. However, the shape of stalagmites can vary significantly during their depositional history, and their morphologic changes such as diameter width depend on both the drip rate and its degree of super-saturation (Dreybrodt 1999). The precipitation of calcite in the speleothem starts at the center, where the deposition rates is the highest, and as the water flows away from the center, the rate decreases with increasing distance (Dreybrodt 1999). This change in drip rates and the spreading of the calcite will create a variety of speleothem shapes. For our study, a new method was applied to calculate deposition rates. Half of the speleothem was photocopied to produce a two-dimensional picture of the sample. Because the speleothems were already dated, each known age was marked on the photocopy. Using the exact location of dates on the speleothem, depositional layers between each date were drawn on the copy to mark the different visible layers within the speleothem (Figure 8). The drawn layers highlighted the amount of calcite deposited between each dated sample. To calculate the volume (mm 3 ) of calcite deposited between the known dates, a frustum of a cone was used because this geometric shape best replicated the calcite deposited between the dates. The formula of the frustum of a cone is: )( 3122RrRrhV [1] 34

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where r is the radius of the upper case, R is the radius of the lower case, and h is the height of the frustum. For certain depositional events within a speleothem, a combination of the frustum and a right circular cylinder had to be used. The equation for the cylinder is: hrV2 [2] where h is the height of the cylinder and r is the radius of the top. To calculate the deposition rate (Calcite deposition) the volume of calcite was divided by the time between dated samples (mm 3 /year). The advantage of calculating deposition rates using this technique is that the volume of calcite between known dates accounts for changes in speleothem morphology that previous techniques did not. Figure 8. Simplified representation of frustum fitting. 35

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36 5. Results 5.1. Uranium-Series Disequilibrium Dating The entire suite of TIMS U-series age es timates for all four speleothems used in this study are presented in Table 1 and Tabl e 2. All ages are reported as years before present. An important finding is that all the li sted Th/U ages are in correct stratigraphic order (Figure 9 and Figure 10). This result suggests that all the speleothems remained closed systems for their entire depositional histories and hence no uranium migration occurred within any speleothem. The high 230 Th/ 232 Th ratios (Table 1) are indicative of very little detrital Th being present in any of the samples. If 232 Th is present in any significant level, the ratio will be lower than what is recorded in Table 1. Second-order polynomial regression pr ovides depositional trends for each speleothem (Figure 9 and Figur e 10). All speleothems display a similar trend, showing a favorable fit of the data to the regression line; the R 2 values for the samples are all above 0.96 (p = 0.001). Both figures demonstrate quite clearly how the calcite deposition rate changes over time. The deposition rates are not linear, having an increase towards the more recent rates. This is more likely due to the change in the morphology of the stalagmite. The initial deposition of the calcite of a stalagmite is spread over a small area due to the flat surface of rock /clay th e calcite is being precipitated upon. As the stalagmite grows in its characteristic conical shape the calcite is deposited over a smaller diameter, and consequently th e rate of growth increases.

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37CorrectedAge(yrs BP)1,2347 33475 38524 32805 701,236 1021,377 611,855 1162,571 474307 1254,461 1454,738 1154,931 18321,078 53424,474 46626,537 58128,998 61729,013 34829,241 680Uncorrected Age (yrs BP)367 32500 36550 29851 661,350 851,424 562,007 882,601 454,332 1254,470 1454,759 1154,966 18321,244 53424,507 46726,548 58129010 61729,033 34829,256 680230Th/238U0.004 0.00.005 0.00.005 0.00.008 0.0010.013 0.0010.014 0.0010.020 0.0010.0026 0.00.041 0.0010.042 0.0010.045 0.0010.047 0.0020.186 0.0040.211 0.0040.224 0.0040.243 0.0040.244 0.0020.246 0.005234U/238U1.068 0.0031.075 0.0031.069 0.0061.071 0.0061.073 0.0071.076 0.0041.075 0.0041.08 0.0031.052 0.0041.051 0.0061.056 0.0061.051 0.0021.052 0.0041.046 0.0031.039 0.0031.042 0.0051.044 0.0041.047 0.004234Ui68.3 2.774.6 3.368.8 6.470.7 6.472.8 7.475.9 3.875.3 4.384.9 2.853.1 4.151.8 5.856.8 6.351.6 2.254.7 4.249.5 3.141.5 3.645.1 5.147.7 4.850.8 4.7230Th/232Th (ppm)184.457 34.143202.396 16.982211.794 12.509182.931 53.974118.076 2.148299.594 9.648130.193 1.888849.901 19.0411695.576 234.1904884.488 1688.5342210.392 400.2271382.019 65.0341164.449 18.9446560.814 588.75821424.532 2528.48420716.540 2749.14012588.754 1876.3693301.469 348.5230Th (ppm)0.00029 0.000020.00039 0.000030.00046 0.000030.00083 0.000030.00170 0.000030.00063 0.000020.00207 0.000030.00051 0.000010.00020 0.000030.00007 0.000020.00012 0.000020.00033 0.000020.00106 0.000020.00023 0.000020.00018 0.000020.00014 0.000020.00016 0.000020.00014 0.00001238U (ppm)0.897 0.0030.972 0.0041.102 0.0051.111 0.0050.928 0.0020.825 0.0010.839 0.0061.033 0.0050.495 0.0020.487 0.0020.365 0.0030.598 0.0020.405 0.0010.446 0.0011.023 0.0060.728 0.0060.516 0.0020.620 0.003Distance from base (mm)141132110905031170167157148125107786043240SampleBRC03-02 BRC03-02 BRC03-02 BRC03-02 BRC03-02 BRC03-02 BRC03-02 BRC03-02 BRC03-03BRC03-03BRC03-03BRC03-03BRC03-03BRC03-03BRC03-03BRC03-03BRC03-03BRC03-031All ages for BRC03-03 corrected using a 230Th/232Th initial ratio of 10 5 ppm. 2All ages for BRC03-03 corrected using a 230Th/232Th initial ratio of 10 2 ppm. Table 1. Uranium-series dates of stalagmites BRC03-02 and BRC03-03.

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38 Figure 9. BRC Cave U-series dating results, age vs. depth plot.

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Figure 10. Briar Cave U-series dating results, age vs. depth plot. 39

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40 Corrected Age (yrs BP)1,21,210 401,482 501,794 531,943 542,163 652,546 373,650 11532 198480 149591 164842 981,192 4481,283 1451,344 1281,826 1152,215 1204,138 369UncorrectedAge(yrsBP)1,263 381,495 501,824 531,987 492,185 652,587 363,891 105246 167748 65817 1201,009 511,359 4411,441 1221,546 781,925 1042,345 1004,553 313230Th/238U0.012 0.00.014 0.00.017 0.00.018 0.00.020 0.0010.024 0.00.036 0.0010.002 0.0020.007 0.0010.008 0.0010.009 0.00.013 0.0040.013 0.0010.014 0.0010.017 0.0010.021 0.0010.041 0.003234U/238U1.008 0.0051.010 0.0051.012 0.0031.013 0.0041.012 0.0031.017 0.0071.018 0.0021.004 0.0041.004 0.0041.008 0.0051.002 0.0041.015 0.0041.002 0.0061.004 0.0041.002 0.0061.004 0.0041.006 0.004234Ui7.6 4.79.7 5.112.5 3.313.5 3.912.2 3.3 17.5 7.018.6 2.44.0 3.54.4 4.08.1 5.31.7 4.215.2 4.42.2 6.24.1 3.51.5 6.43.8 4.16.1 4.4230Th/232Th (ppm)233.779 3.8871136.072 601.513 21.363446.026 8.324989.225 45.085622.356 18.345158.702 1.96711.484 0.21627.865 0.31336.079 0.65460.312 0.93681.164 1.93290.647 1.75075.979 1.141193.374 7.104178.632 5.111112.606 1.098230Th (ppm)0.00084 0.000010.00025 0.000020.00055 0.000020.00091 0.000020.00034 0.000020.00060 0.000020.00439 0.000050.00153 0.000030.00161 0.000020.00136 0.000020.00095 0.000010.00102 0.000020.00099 0.000020.00106 0.000020.00042 0.000020.00068 0.000020.00361 0.00003238U (ppm)1.031 0.0061.249 0.0101.201 0.0071.353 0.0101.030 0.0060.953 0.0071.193 0.0060.474 0.0020.399 0.0020.399 0.0020.381 0.0020.403 0.0020.418 0.0030.349 0.0020.285 0.0020.346 0.0020.607 .003Distance from base (mm)13011095775827023521519517015013510378430SampleBRIARS04-01BRIARS04-01BRIARS04-01BRIARS04-01BRIARS04-01BRIARS04-01BRIARS04-01BRIARS04-02BRIARS04-02BRIARS04-02BRIARS04-02BRIARS04-02BRIARS04-02BRIARS04-02BRIARS04-02BRIARS04-02BRIARS04-021All ages assuming a 230Th/232Th initial ratio of 10 2 ppm. Table 2. Uranium-series dates of stalagmites BRIARS04-01and BRIARS04-02

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41 5.2. Calcite Deposition Rates Uranium-series ages for all the speleothem s are presented in Table 1 and Table 2. Although the BRC Cave speleothems were init ially thought to have been deposited concurrently, the U-series ages show that is not the case for all the speleothems (Table 1). BRC03-02 grew from around 2.6 ka BP till present, and BRC03-03 was deposited during two periods spanning part of the last glacial interval and the middle of the Holocene. The average depositional rate (calcite deposition) for BRC03-02 was 375 mm 3 /yr (Table 3 and Figure 11). During the ear ly stage of accumulation, the deposition rate was 63 mm 3 /yr, which is considerably lower than its average. A significant change occurred from 1.8 to 1.3 ka BP, wh en the rate incr eased to 337 mm 3 /yr. Deposition continued to increase from 1.3 to 1.2 ka BP years ago (326 mm 3 /yr). At around 500 years ago the deposition rate increas ed considerably to 1164 mm 3 /yr, the highest recorded for any of the four speleothems. This change c ould indicate an increase in drip rate, either from enhancement of secondary porosity of the above bedrock (which is unlikely) or from increased precipitation. BRC03-03 was deposited from 29 to 21 ka BP, followed by a 15 ka hiatus and then from 5.2 to 4.0 ka BP (Table 3 and Figur e 11). The average depositional rate for the glacial calcite was ~40 mm 3 /yr, and 354 mm 3 /yr for the Holocene. During the Glacial Period, the deposition rate decreased from 63 mm 3 /yr at 29 ka BP to14 mm 3 /yr by 21 ka BP. Figure 11 shows a decrease in deposition during this period, a tr end that appears to record the decline in precipitation as the re gional climate headed into the Last Glacial Maximum. Deposition then ceased for ~15,000 years until the mid-Holocene when new

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42 calcite deposition started ~5.2 ka BP. The Ho locene deposition rates represent a ~ 400% increase compared to the Last Glacial Maximum. It is well recognized that rainfall amounts were much lower during the last gl acial period compared to the Holocene (Watts and Hansen 1994).

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43Table 3. Calcite deposition rates for Floridian speleothems.BRC03-022571-18557164480063BRC03-021855-1377478161000337BRC03-021377-123614145900326BRC03-021236-80543167100156BRC03-02805-52428165200232BRC03-02524-4754957001200BRC03-02475-34712865300510BRC03-02347-034773800213BRC03-02380BRC03-03 Glacial29241-290132281570069BRC03-03 Glacial29013-265376293260052BRC03-03 Glacial26537-2447424765913024BRC03-03 Glacial24474-2107833964816014BRC03-03 Glacial40BRC03-03 Holocene5200-4931269110000410BRC03-03 Holocene4931-4738193100000520BRC03-03 Holocene4738-446127756900206BRC03-03 Holocene4461-430715443400282BRC03-03 Holocene354BRC03-03 Total200BRIARS04-013650-254611044365040BRIARS04-012546-216338376300199BRIARS04-012163-192922084700385BRIARS04-011929-179414954600366BRIARS04-011794-148231254300174BRIARS04-011482-121027249400182BRIARS04-01224BRIARS04-024138-221519239806051BRIARS04-022215-1826389309000795BRIARS04-021826-1344482106000220BRIARS04-021344-12836159000970BRIARS04-021283-11929179000870BRIARS04-021192-84235093800268BRIARS04-02842-591251116000461BRIARS04-02591-480111102000915BRIARS04-02480-324482720061BRIARS04-0232-03226000800BRIARS04-02540SampleDistance from Base (years)Time of deposition (years)Volume of Calcite (mm3)Average Deposition RateAverage Deposition RateAverage Deposition RateCalcite deposition (mm3/yr)Average Deposition RateAverage Deposition RateAverage Deposition Rate

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44 Figure 11. Calcite deposition rates for Floridian speleothems.

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The restart of calcite deposition for BRC03-02 (after 15 ka hiatus) had not been measured using U-series analysis, and so an age had to be interpolated using the lower regression equation from Figure 9. The strong regression coefficient (R 2 = 0.97, p = 0.001) allowed a high level of confidence that this interpolation is close to the actual date. Figure 12 shows the extension of the regression line through to when the deposition started again at 110 mm above the base of the speleothem. This yielded an age of 5.2 ka BP. Figure 12. BRC03-03 Interpolation of age at 5.2 ka BP, after 15 ka hiatus. Speleothems collected from Briar Cave were also analyzed for their deposition rates. BRIARS04-01 was deposited from 3.6 to 1.2 ka BP with an average rate of deposition of 224 mm 3 /yr although rates ranged from 40 to 385 mm 3 /yr (Table 3 and Figure 11). The deposition rate was the lowest from ~ 3.6 to 2.5 ka, attaining a value of 40 mm 3 /yr but then dramatically increased to ~385 mm 3 /yr from 2.1 to 1.9 ka BP. 45

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46 The rate remained high (366 mm 3 /yr) from 1.9 to 1.8 ka BP but then declined 50% over the next 400 years. Stalagmite BRIARS04-02 was deposited continuously from 4.5 ka BP until present, with an average deposition rate of 542 mm 3 /yr, the highest of all the speleothems (Table 3 and Figure 11). This average is cl ose to BRC03-02, indicating an increase in calcite deposition during the last 2,000 years, suggesting wetter conditions for the region as a whole. A slow deposition rate of 51 mm 3 /yr was recorded for BRIARS04-02 for its first 2.0 ka (4.1 to 2.2 ka BP), although the lack of dates during this period may disguise variable deposition rates. From ~ 2.2 to 1.8 ka BP a significa nt increase in deposition was recorded, which is consistent with a sim ilar increase for BRIARS04-01. This agreement is strong evidence that the different drip sites within the same cave can be responding similarly to changes in precipitation. The rate was the highest from 1.35 to 1.3 ka BP, attaining a value of 972 mm 3 /yr. Another major change was recorded from 600 to 480 years ago, with a deposition rate of 915 mm 3 /yr this increase was also recorded in the speleothem BRC03-02, indicating an increase in precipitatio n for the region, not only for this single cave. 5.3. Stable Isotopic Analysis Ages were assigned to these stable is otopic data using lin ear interpolation between U-series-dated portions of calcite. The polynomia l regression equations shown in the results section to describe the indi vidual stalagmite depos ition trends were not used. While these equations provided a good approximation of the entire suite of dates

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47 per speleothem, they cannot re present with total accuracy the date every single isotopic value. Consequently, using these equations would have assigned erroneous ages to stable isotopes, a problem simple li near interpolation reduces. The 18 O values for stalagmite BRC03-02 are shown in Figure 13. Maximum 18 O values of ~-4 occur at the base of the speleothem ~ 2.6 ka BP after which began a 500-year trend towards lighter is otopic values. At ~2.0 ka BP, 18 O values plateaued for 600 years followed by a continuation of the sh ift towards lighter isotopic values. This trend ceased at 0.9 ka BP, which is commonly regarded as the height of the MWP (Haug et al. 2001; Bradley et al. 2003). After this period of enhanced warmth/wetness, the speleothem experienced a shift towards heav ier values once again, culminating in the LIA (Grove 1998; OBrien et al. 1995; Hodell et al. 2005). This shift towards heavier values we interpret as a decrease in precipitation for the area. The 13 C record for BRC03-02 fluctuates be tween -11 and -12.5 with a -12 average (Figure 13). This small difference in values indicates that there were no major vegetation changes during the deposition of this speleothem. The average 13 C value of 12 suggests an abundance of C 4 vegetation, i.e. a forested environment. The only feature of interest for this record is that the minimum isotopic values are reached around the same time as those of the 18 O values (~1.0 ka BP), which can be interpreted as wetter conditions producing a s lightly denser forest cover. The lack of correspondence between the oxygen and car bon isotopes confirms the isotopic equilibrium of the speleothem.

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Figure 13. Stable oxygen and carbon isotope records for BRC03-02. The isotopic results for the second speleothem from BRC Cave, BRC03-03, were divided in two periods, Glacial and Holocene due to their separate depositional intervals. Figure 14 shows the isotopic values over time during the Glacial period. The first striking feature is the difference in the 18 O values compared to the Holocene speleothem BRC03-02, with BRC03-03 having much heavier isotopes. Staying with the wet-dry 48

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interpretation of our isotopes, these values strongly show a very dry environment, as may be expected for a glacial period. Maximum dryness occurred ~25 ka BP, after which a short wetter period is centered around 24 ka BP. Similar wetter conditions are apparent ~29 ka BP. Growth ceased at 21 ka BP which is the Last Glacial Maximum. Figure 14. Stable oxygen and carbon records for BRC03-03, during the Glacial Period. 49

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50 The 13 C record fluctuates between -10 to -4.75 (Figure 14). This variation shows significant changes in vegetation above the cave, with 5.2 change centered on 25 ka BP, sufficient enough to sugge st a shift in vegetation from C 3 to C 4 plants which we interpret as changes in vegetation from forest to savannah-type vegetation, indicative of the drier conditions found in our 18 O values at the same tim e. Dorale et al. (1998) interpreted transitions between forest and grassland environments using a 4 shift in the speleothem calcite. A nother study by Denniston et al. ( 2001) interpreted a ~ 2 decrease as sufficient to observed changes between prai rie to forest environment. Hence, the 5.2 shift in our 13 C data must be indicative of a major vegetational change. Holocene records for stalagmite BRC03-03 are shown in Figure 15. The 18 O values show increased precipitation at 4.25 a nd 5.05 ka BP and drier periods between 4.7 to 4.95 ka BP and another centered on 4.2 ka BP. There appear to be corresponding decreases in forest density due to these prec ipitation changes, with a less dense forest occurring during the dry peri od 4.7-4.95 ka BP and the other ~4.25 ka BP. However, there were no dramatic vegetation changes that characterized the prior glacial period.

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Figure 15. Stable oxygen and carbon record for BRC03-03, during the Holocene. Oxygen isotopic results for Briars04-01 are shown in Figure 16. The 18 O signal shows a trend toward higher values at ~2.3 ka BP, followed by a decrease in values at ~1.7 ka BP, and an increase in value at ~1.1 ka BP. The 18 O record fluctuates between -3.29 to -5.02, with an average of -4.18. (Note due to technical problems a full 51

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52 record of the speleothem was not obtained at the time of this research; the spaces between the data do not represent a hiatus in the record). Carbon isotopic results ar e shown in Figure 16. The 13 C signal shows a depletion ~2.7 ka BP, followed by a more-stable period from 2.5 ka BP to 1.5 ka BP. The record displays fluctuations in the carbon isotope s, suggesting changes in the density of vegetation above the cave. A lthough no significant changes in vegetation occurred during the Holocene as recorded by other speleothems, the variability in BRIARS04-01 is due to the higher sensitivity of the record.

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Figure 16. Stable oxygen and carbon isotope records for BRIARS04-01. Stable isotopes for BRIARS04-02 are shown in Figure 16. The 18 O signal shows an initial depletion from 4-3 ka BP, followed by fairly stable precipitation conditions from 3 to 1.3 ka BP. This stable interval is punctuated by one brief increase in precipitation at ~1.85 ka BP. After 1.3 ka BP, the speleothem experiences a transition to 53

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54 wetter conditions, which is universally recognized as the MWP. From 0.8 ka until present, enrichment of the values occurs, denoting drier conditions of the Little Ice Age. The 13 C record shows a depletion from 4.2 3.5 ka BP signaling a more lush forest over the cave (Figure 16). Since this period, small deviations occurred in the record, but none significant enough to warrant special mention. These small changes suggest that the vegetation (i.e. forest vegetation) remained constant during last three millennia.

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Figure 17. Stable oxygen and carbon record for BRIARS04-02. 5.4. Isotopic Equilibrium A comparison between coeval speleothems collected from Briar Cave is shown in Figure 18. The comparison between the 18 O values over time for the two speleothems 55

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from Briar Cave shows that little fractionation occurred during calcite deposition. This relationship confirms that the speleothems were deposited under isotopic equilibrium conditions. The match is not ideal but there are trends in the peaks and troughs, suggesting that the speleothems were recording similar climatic changes above the cave. There are several reasons for why the peaks do no match; there are variations in the isotopic signal in different parts of the caves, (the samples were not collected right next to each other) and there are differences in the interpolation of the stable isotopes between the dates, (the dates were not collected at the same time periods for each speleothem). Considering all the things that can probably make them different, we think there is a similarity in the signal and both speleothems were deposited in isotopic equilibrium. Figure 18. Comparison between BRIARS04-02 and BRIARS04-01, showing isotopic equilibrium for the cave. 56

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57 6. Discussion Speleothems collected from the two Florid a caves record hydrologic responses to changing climatic phenomena that aff ect the Floridian Peninsula. The 18 O isotopes provide indirect measures of the precipitati on amount, and the 13 C provide information of the type of vegetation growing above the cav e. Based on U-series an alysis, the ages of the speleothems were determined, which prov ided information on changes in the calcite deposition rates of the speleothems. By c oupling the results from the Uranium-series with the stable isotopic information, we ar e able to create a chronologically accurate record of Floridas Holocene paleoclimate. 6.1. Verification of Region al Paleoclimate Signal The next step in our analysis is to determine whether our interpretation of Floridas paleoclimate, as derived from speleo thems, agrees with previous paleoclimatic studies. These records are: Lake sediments from Lake Tulane (Cross et al. 2004), tree-ring data (surrogate fo r precipitation) from the s outheastern US (Stahle and Cleaveland 1992), changes in sea surface temperatur e as recorded by NINO3 (Cane 2005) and a record of titanium concentra tion in the Cariaco Basin of the Caribbean Sea (Haug et al. 2001). Speleothem BRIARS0402 was selected because of its continuous record over the last 4, 200 years.

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6.1.1. Speleothems BRIARS04-02 and BRC03-02 A correlation between stalagmites collected from BRC Cave and Briar Cave is shown in Figure 19. BRC03-02 and BRIARS04-02 18 O records show very similar trends in their data which suggests that both speleothems are responding to a regional shift in climate and not a purely localized change. A second important point is that if either record was subject to isotopic fractionation, it would be highly unlikely that these two records would match so closely. Both stalagmites record the MWP and the LIA. However, there is some disagreement, in some of the smaller deviations in the isotopes, which is probably caused by localized climate differences or noise in the signals. Figure 19. Correlation between speleothems 18 O of BRIARS04-02 and BRC03-02 18 O records. 58

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59 6.1.2. Lake Tulane and the Speleothems Lake Tulane is the most significant paleoclimate record for Florida during the last 50 ka. The lake is of sufficient depth to ha ve avoided desiccation over this period and the chemical composition of the lake waters is consistent throughout th e year. There appears to be continuous sedimentation in th e lake during the past 100,000 years (pers. comm., D. Hollander 2005). The pollen reco rd from the lake is one of the longest uninterrupted sequences in North America (G rimm et al. 1993). The most recent work by Cross et al. (2004) using D of lipids extracted from Lake Tulane sediments for the last 2.0 ka, produced a record of changes in relative humidity for this site. A positive correlation between relative humidity and precipitation amount is to be expected, and indeed the lake record of re lative humidity corresponds to the shifts recorded in the 18 O of BRC03-02 and BRIARS04-02 (Figure 20). All three curves have lower values around the MWP and higher values during the LIA. Because this trend appears in all three records, we interpret it as a regional trend for the Florida peninsula.

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Figure 20. Comparison between 18 O of BRC03-02 and BRIARS04-02, to D record from Lake Tulane, Florida (Cross et al. 2004). 6.1.3. South East Precipitation Tree-ring data of bald cypress from South Carolina, North Carolina and Georgia have been used to reconstruct the spring rainfall over the Southeastern U.S. for the last 1,000 years (Stahle and Cleaveland 1992). Our most detailed record of precipitation and the one closest to these three states is BRIARS04-02. The fluctuations in the SE USA precipitation record match very closely 60

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the variability in the 18 O values (Figure 21). The SE USA precipitation record only dates back to 1.0 ka BP, whereas the speleothem goes back to ~4.2 ka BP. Consequently, the stalagmite 18 O records extends the precipitation record another 3.2 ka. (Note the xaxis for precipitation (i.e. tree ring width) has been reversed, due to our interpretation of Floridas paleoclimate (increase in precipitation = depleted isotopes)). These comparison between the 18 O of the speleothem and the other surrogate records of Floridas Holocene precipitation change achieve two objectives: 1) they confirm our interpretation of the isotopic records, 2) they suggest that a common regional precipitation exists for Florida. The next step is to examine some of the potential causes of these changes in precipitation. Figure 21. Correlation between 18 O of BRIARS04-02 with the SE US precipitation (Stahle and Cleveland 1992), as derived from tree-rings. 61

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62 6.2. Causes of Holocene precipitation change in Florida 6.2.1 AMO The correlation with the SE USA tr ee-ring record and the BRIARS04-02 18 O is presented in Figure 21. Enfield et al. (2001) suggests the main cause for precipitation variability is the Atlantic Multi-decadal Os cillation (AMO). This os cillation is driven by changes in pressure difference between the North Atlantic High (NAH) and the Icelandic Low. Large pressure differences lead to stronger winds that push warm water from the lower latitudes to the higher latitudes, increasing precipita tion along the eastern seaboard, including Florida. Small pressure differences produce drier conditions. 6.2.2. El Nio (NINO3) El Nio is also influential for precipita tion in Florida, bringi ng more precipitation to the SE USA. NINO3, refers to the s ea surface temperature (SST) anomaly in the NINO3 region of the eastern equatorial Pacifi c, and is a commonly used index of El Nio activity (Cane 2005). Once again we use BRIAR S04-02 as the record of precipitation amount for western Florida. Figure 22 show s the comparison between the stalagmite 18 O and NINO3. Although El Nio events produce greater amounts of winter precipitation for Florida, the rainfall will be isotopically depl eted due to the cooler winter temperatures, which is still in agreement with our interpretation of the isotopic signal of Floridian speleothems. The changes in NINO3 record the variable intensity of El Nio that occurs at a slower pace than those of the AMO, whic h has a 60-80 year cycle. The slight offset

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seen in Figure 22 was added because the NINO3 record has a 40-year running mean which shifted the peaks and troughs of the index. Figure 22. Comparison between 18 O from BRIARS04-02 to NINO3 Index from Cane (2005). The arrows represent match between troughs. 63

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64 6.2.3. Cariaco Basin One final influence on the precipita tion of Florida and consequently the 18 O values of our speleothems is the Intertropi cal Convergence Zone (ITCZ). Changes in the relative position of the ITCZ causes correspond ing shifts in the position of the NAH. A migration north of the ITCZ would lead to a NE shift of the NAH, moving the easterlies influence to direct moist air into Florida and creating wetter conditi ons. Such a shift has been proposed by Haug et al. (2001) as the cause for wetter conditions during the MWP in the Cariaco Basin, located off the northern co ast, South America. Their titanium record in marine sediments represents increases in continental runoff as the ITCZ moved northward. This Ti% record correlates with BRC03-02 and BRIARS04 (Figure 23), especially the increase in precipitation during th e MWP (higher Ti values and lower 18 O values). Less precipitation during th e LIA (lower Ti values and higher 18 O values) are interpreted as a southward m ovement of the ITCZ. (Note the x-axis Ti-record for the Cariaco Basin has been reversed, due to our interpretation of Fl oridas paleoclimate).

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Figure 23. Comparison of 18 O from BRC03-02 and BRIARS04-02 to Cariaco Basin Ti% record (Haug et al. 2001). 6.3. Floridas paleoclimate during the last Ice Age Grimm et al. (1993) studied oscillations of pine pollen for Lake Tulane, FL, and found a correlation with the North Atlantic Heinrich events over the last 50 ka. The Heinrich events are massive periodic advances of ice streams from the eastern margin of the Laurentide Ice Sheet (Heinrich 1988; Ruddiman 2001). The correlation between Heinrich events and the major changes in the temperature of the North Atlantic suggested that fresh water releases were the result of the melting of the Heinrichs icebergs, which disrupted deep-water formation, thereby permitting switches between glacial and interglacial modes of thermohalines circulation (Broecker 1994).They interpreted their 65

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66 record as wetter soil conditions during Heinri ch events due to lower evaporation rates, which favored an increase in Pinus, whose pollen was then found in greater abundance in Lake Tulane. They suggested the cause of lowe r evaporation was an influx of cold glacial water into the Gulf of Mexico. Our speleo them BRC03-02 records climate change from 30-21 ka BP (Figure 22). From 27 to 25 ka BP, it experienced substantial dryness as shown by the 13 C signal, this event is recorded in Lake Tulane as Heinrich event 3 (Grimm et al. 1993). The beginning of H2 was also recorded by the speleothem 13 C record. The cooler conditions and lower eva poration rates may have increased the water balance in low-lying Lake Tulane, but on th e Brooksville Ridge, cooler climate would have reduced precipitation (as shown by the 18 O values at this time), resulting in a shift towards a savannah-type vegeta tion state above the cave. Between 24 to 25 ka BP, there was an incr ease in precipitatio n recorded by both the 18 O and corresponding shift to forest-l ike conditions as recorded by the 13 C record. Drier conditions were also reco rded at ~21 ka BP characterized by cooler temperatures at the start of the Last Glacial Maximum, which led to a cessation of growth for the speleothem.

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Figure 24. Comparison between the 13 C from BRC03-02 (Glacial) and the pollen record from Lake Tulane (Grimm et al. 1993). 6.4. Teleconnections controlling precipitation in Florida A teleconnection, as defined by the American Meteorological Society, a linkage between weather changes occurring in widely separated regions of the globe (Huschke 1959). A close correlation between the isotopic record from BRIARS04-02 and surrogate records that represent various potential influential teleconnections for Florida and other locations suggest teleconnections operating at the decadal and centennial scale. These lead to changes in both precipitation amount and vegetation at a regional level. 67

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68 Figure 25 shows our interpretation of the teleconnections affecting our speleothem isotopic records. 1) The AMO is driven by changes in the sea-surface temperature of the North Atlantic Ocean. During warm water periods (known as the warm phase of the AMO), rainfall in south and central Florida will increase (Physical Oceanography Division/ NOAA). This agrees wi th the study by Enfield et al. (2001) that found a positive relation between the decadal changes of AMO and river discharge over the 20 th century for Florida. When the AMO enters a cool phase, precipitation decreases above the caves. Our surrogate for the AMO wa s SE USA precipitation as derived from tree ring data (Stahle and Cl eaveland 1992). Enfield et al. (2001) suggested the SE USA tree-ring record was strongly influenced by the AMO. Consequently, our close correlation with the SE USA precipitation r ecord for the last 1.0 ka suggests a strong AMO control on Floridas prec ipitation. Furthermore, our sp eleothem record extends back to 4.2 ka BP, thereby adding another 3,000 years of precipitation reconstruction to the tree ring record. The correlation between speleothem isotopic record and the surrogate for the AMO points toward a tel econnection between subtropical Florida and the higher latitudes of the North Atlantic.

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Figure 25. Diagram showing teleconnections occurring around Florida; background image NASA/JPL/NIMA. 69 El Nio is a climatic pattern that is marked by warm-sea surface temperatures in the eastern tropical Pacific and associated climatic shifts around the globe, off the coast of South America (Cane 2005). During periods of warm El Nio phases, precipitation will increase in Florida as shown by Winsberg (1994). The strong correlation of BRIARS04-02 and NINO3, an index measuring El Nio intensity, has been shown for the last 1.0 ka. Enfield et al. (2001) found a combined influence of changing El Nio intensity and the AMO, again for the 20 th century. This relationship suggests a

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70 teleconnection originating in the tropical Pacific. Once more, our speleothem records extend this relationship between precipitation and El Nio for Florida back to 4.2 ka BP. These changes in the intensity of El Nio tend to be decadal in scale (Cane 2005). The ITCZ is located around the equato r and is generated by the convergence of the northeasterly and southeasterly trade-winds Changes in the relative position of the ITCZ, as it moves north or south will cause changes in precipita tion for equatorial regions. If the ITCZ moves north it will cause a northeast movement in the relative position of the NAH. This change in the NAH will move the easterlies that wrap around the high, and as a result, they direct moist air towards Florida, thereby increasing precipitation. This long-term (centuries) influence explains the changes in the precipitation during the MWP-LIA as shown by the correlation between BRIARS04-02 and the Cariaco Basin Ti% (Figure 23), the surrogate for the positi on of the ITCZ (Haug et al. 2001). Hence, the final telec onnection is a combination of the changing ITCZ position and its effect on the NAH, lead ing to centennial-scale shifts, and the largest changes in precipita tion amount for Florida, as record during the MWP-LIA transition.

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71 7. Conclusions This study represents the first speleothem -based paleoclimate research for Florida, using stalagmites collected from BRC Cave and Briar Cave. The speleothem 18 O recorded indirectly changes in precipitation amount occurri ng in Florida for the last 4,200 years. In Florida, larger storms have stronger convection therefore precipitation; forms at higher altitudes generating isotopical ly depleted precipitation and taller thunderheads produci ng more precipitation. Evidence of this relationship between isotopic composition and amount of rainfall have been shown by the studies of Lachniet et al. (2004) and Fleitmann et al. (2003). Consequently, depleted speleothem 18 O values indirectly relate to incr eased precipitation. Variations in the 13 C of cave calcite can be attributed to changes in vegetation above the cave, although the isotopic shifts should be > 3-4 (Dorale et al. 1992). For this study a new method for calculating calcite deposition rates was developed. Previous methods were not taking into account the changing morphology of the speleothem. This new method uses volumetric measurements of calcite deposited between (TIMS) ages (mm 3 /yr). There seems to be certain periods of agreement between of decreased and increa sed growth for the speleothems specially at intervals centered on 2 ka BP and 0.5 ka BP.

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72 Speleothems from the same cave and two different caves, were compared to determine if they recorded similar isotopi c signals. If so, then a regional climate signal would be measured in the cave calc ite. A close correlation would also provide strong evidence of the speleo thems being deposited in is otopic equilibrium with the dripwater at each site. A cl ose correlation between speleo thems collected from BRC Cave and Briar Cave in Florida was evident, suggesting a regional shift in climate and also isotopic equilibrium for both caves. The speleothems 13 C isotopes recorded stable c onditions above the cave during the Holocene (with the exception of BRI ARS04-01). The oldest speleothem (BRC03-02) grew during the latter part of the last glacial period, and both the oxygen and carbon isotopes showed a drier climat e than today with a savannah-type vegetation, with the exception of two short-lived forested episodes. The speleothem ceased growing at the Last Glacial Maximum. Speleothem record was also compared to other regional climate records, such as the Stahle and Cleveland (1992) SE USA pr ecipitation record and the Lake Tulane D lacustrine (Cross et al. 2004). BRIAR S04-02 provides the highest resolution record (going back 4,200 years) and theref ore was used to compare to these other paleoclimate records. Close agreemen t was observed between the calcite 18 O speleothem and the SE USA precipitation record and the Lake Tulane records. Consequently, the factors that are generati ng these shifts in climate cover the whole SE USA and are probably affecting an even broader area. These large-scale climatic influences are the AMO, El Nio and the ITCZ. The first two produce short-term changes in precipitation amount for the region.

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73 The AMO, as suggested by Enfield et al. (2001), will cause changes in precipitation that have a decadal cyclicity ( 60-80 years). This variability is shown in the SE USA precipitation record (Stahle and Clev eland 1992) and the close correlation with the speleothem BRIARS 04-02 suggesting a strong influence on the precipitation signal recorded in the speleothem. Enfield et al. (2001) also noted the influence of El Nio on Floridas precipita tion, with changes in it s intensity that are also decadal in nature (as measured by NINO3 Cane 2005). Once again, a strong agreement exists between BRIARS04-02 and NINO3. Hence, a coupled influence to both the AMO and the changing intensity of El Nio affect short-term precipitation changes in Florida. Longer-term shifts in the mean position of the ITCZ and its effect on the NAH position are recorded in the Cariaco Basi n Ti% record (surrogate for the ITCZ movement Haug et al. 2001), signal that was correlated with BRIARS04-02. The close match shows that the NAH, as influen ced by the ITCZ, also affects precipitation in Florida. This influence is centennial in nature, with changes in precipitation occurring during the MWP-LIA. A final conclusion to be taken from this study is which teleconnections are influential over Florida for the latter part of the Holocene. As noted above, the AMO, El Nio and ITCZ all affect Floridas clim ate. Consequently, the teleconnections are both Equatorial (ITCZ and El Nio) and from the higher latitudes (AMO). Such a result can be expected due to Florida s subtropical location, sitting between both latitudinal zones.

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74 8. References Alvarez Zarikian, C.A., Swart, P.K., Giffo rd, J.A., Blackwelder, P.L., 2005. Holocene Paleohydrology of Little Salt Spring, Florida based on ostracod assemblages and stable isotopes. Paleogeography, Paleoclimat ology, Paleoecology, v. 225, pp. 134-156. Armstrong, B., Chan, D., Collazos, A., Mallams, J.L., 2003. Doline and Aquifer Characteristics within Hernado, Pasco, and Northern Hillsborough Counties. Karst Studies of West Ce ntral Florida. pp. 39-51. Baker, A., Genty, D., Dreybrodt, W., Barnes, W.L., Mockler, N.J., and Grapes, J., 1998. Testing theoretically predicted stalagm ite growth rate with recent annually laminated samples: Implications for past stalagmite deposition. Geochimica et Cosmochimica Acta, v. 62, pp. 393-404. Bradley, R.S., Hughes, M.K., Diaz, H.F., 2003. Climat e in Medieval Time. Science, v. 302, pp. 404-405. Broecker, W.S., 1994. Massive iceb erg discharges as triggers for global climate change. Nature, v. 372, pp. 421-424. Cane, M.A., 2005. The evolution of El Ni o, past and future. Earth and Planetary Science Letters, v. 230, pp. 227-240. Coplen T. B., 1994. Reporting of stable hydrogen, carbon and oxygen isotopic abundances. Pure and Applied Chemistry. V. 66, pp. 273276. Craig, H. 1961. Isotopic variation in me teoric waters. Science, v. 133, pp. 1702-1703. Cross, E., Hollander, D.J., Huang, Y. and Van Vleet, E., 2003. Seattle Annual Meeting, Geological Society of America Abstracts with Programs, v. 35, no. 6, p. 61. Cross, E., Hollander, D.J., Huang, Y. and Van Vleet, E., 2004. Hydrogen Isotopic Ratios of Lacustrine Algal and Terre strial Organic Matter as a Quantitative Proxy for the Reconstruction of Relative Humid ity and Source Water Composition in Continental Settings. American Geophysic al Union, Fall Meeting 2004, abstract #PP42A-03.

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75 Curl, R.L., 1973. Minimum diameter stalag mites. National Speleological Society Bulletin, v. 35, pp. 1-9. Dansgaard, W. 1964. Stable isotopes in precipitation. Tellus, v. 16, pp. 436-468. Deines, P., 1980. The isotopic composition of reduced organic carbon. In: Handbook of Environmental Isotope Geochemistry ( P. Fritz and J.Ch. Fontes eds.), v. 1. Elsevier, New York, pp. 329-406. Denniston, R.F., Gonzalez, L.A., Asmerom, Y ., Reagan, M.K., 2000. Speleothem records of Holocene paleoenvironmental ch ange in the Ozark Highlands, USA. Quaternary International, v. 67, pp. 2128. Dorale, J.A., Edwards, R.L., Ito, E. and Gonzlez, L.A., 1998. Climate and vegetation history of the midcontinent from 75 to 25 ka: A speleothem record from Cevice Cave, Missouri, USA, Science, v. 282, pp. 1871-1874. Dorale, J.A., Edwards, R.L., and Onac, B. P., 2002. Stable isotopes as environmental indicators in speleothems. In: Yuan, D.-X. (ed.), Kars t Processes and the Carbon Cycle, 107-120. Geological Publis hing House, Beijing, China. Dorale, J.A., Gonzlez, L.A., Reagan, M.K., Pickett, D.A., Murrell, M.T., Baker, R.G., 1992. A hig-resolution record of Holocene cl imate change in speleothem calcite from cold water cave, northeas t Iowa. Science, v. 258, pp. 16261630. Dreybrodt, W., 1999, Chemical kinetics, speleo them growth and climate. Boreas, v. 28, pp. 347-356. Enfield, D. B., A. M. Mestas-Nuez, and P. J. Trimble, 2001. The Atlantic multidecadal oscillation and its relation to rainfall a nd river flows in the continental U. S., Geophysical Research Letters, v. 28, pp. 277-280. Faure, G., 1986, Principles of Isotope Ge ology: New York, John Wiley and Sons, 589 p. Filley, T.R., Freeman, K.H., Bianchi, T.S., Ba skaran, M., Colarusso, L.A., Hatcher, P.G., 2001. An isotopic bigeochemical assessment of shifts in organic matter input to Holcene sediments from Mud Lake, Florida. Organic Geochemistry, v. 32, pp. 1153-1167. Florea, L., Hashimoto, T., Kelley, K ., Miller, D., Mrykalo, R., 2003. Karst Geomorphology and Relation to the Phreatic Surface, Briar Cave, Marion County, Florida. Karst Studies of We st Central Florida. pp. 9-19.

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76 Fleitmann, D., Burns, S.J., Mudelsee, M., Neff, U., Kramers, J., Mangini, A., and Matter, A., 2003. Holocene forcing of the Indian m onsoon recorded in a stalagmite from southern Oman. Science, v. 300, pp. 1737 Ford D.C. and Williams, P.W., 1989 Karst geomorphology and hydrology Unwin Hyman: London. Friedman. I. and Smith, G.I., 1970. Deuterium content of snow cores from Sierra Nevada. Science, v. 169, pp. 467-470. Franke, H.W., 1965. The theory behind stalagm ite shapes. Studies in Speleology, v.1, pp. 89-85. Frumkin, A., Ford, D.C., Schwarcz, H.P., 1999. Continental oxygen isot opic record of the last 170,000 years in Jerusalem. Quaternary Research, v. 51, pp. 317-327. Frumkin, A., Schwarcz, H. P. and Ford, D. C., 1994. Evidence for Isotopic equilibrium in stalagmites from caves in a dry region: Je rusalem, Israel. Israel Journal of Earth Sciences, v. 43, 3-4, p. 221-230. Frumkin, A., and Stein, M., 2004. The Sahara East Med iterranean dust and climate connection revealed by strontium and uranium isotopes in a Jerusalem speleothem. Earth and Planetary Science Letters, v. 217, pp. 451-464. Gascoyne, M., 1992. Paleoclimate determination from cave calcite deposits. Quaternary Science Reviews, v. 11, pp. 609-632. Genty, D., and Quinif, Y., 1996. Annually lamina ted sequences in the internal structure of some Belgian stalagmitesimporta nce for paleoclimatology. Journal of Sedimentary Research, v. 66, pp. 275-288. Grimm, E.C., Jacobson, G.L., Watts, W.A., Hansen, B.C., Maasch, K.A., 1993. A 50,000-year record of climate oscillati ons from Florida and its temporal correlation with the Heinrich events. Science, v. 261, pp. 198-200. Gremillion, P. and Wanielista, M., 2000. Effects of evaporative enrichment on the stable isotope hydrology of central Florida (USA ) river. Hydrological Processes, v. 14, pp. 1465-1484. Harmon, R.S., H.P. Schwarcz, M. Ga scoyne, J.W. Hess and D.C. Ford., 2004. Paleoclimate information from speleothems: The present as a guide to the past. In: Studies of Cave Sediments Physical and Chemical Records of Paleoclimate (I.Saskowski.and J. Mylroie, eds.), Klewer Academic/Plenum Publishers, New York. pp. 199-224.

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77 Haug, G.H., Hughen, K.A., Sigman, D.M ., Peterson, and L.C., Rhl, U., 2001. Southward migration of the Intertropical Convergence Zone through the Holocene. Science, v. 293, pp. 1304-1308. Heinrich, H., 1988. Origin and consequences of cy clic ice rafting in th e northeast Atlantic Ocean during the past 130,000 years. Quaternary Research, v. 29, pp. 142152. Hendy, C., 1971, The isotopic geochemistry of speleothems I. The calculation of the effects of different modes of form ation on the isotopic composition of speleothems and their applicability as pal aeoclimatic indicators. Geochimica et Cosmochimica Acta, vol. 35, pp. 801-824. Henning, C.J., Grun, R., and Brunnacker, K., 1983. Speleothems, travertines and paleoclimates. Quaternary Research, v. 20, pp. 1-29. Hodell, D.A., Brenner, M., Curtis, J.H., Medina-Gonzalez, R., Ildefonso-Chan, E., Albornaz-Pat, A., Guilderson, T.P., 2005. Climate Change on the Yucatan Peninsula during the Little Ice Age. Quaternary Research, v. 63, pp. 109-121. Holmgren, K., Karlen,W., Lauritzen, S.E., L eeThorp, J.A., Partridge, T.C., Piketh, S., Repinski, P., Stevenson, C., Svanere d, O., and Tyson, P.D., 1999. A 3000-year high-resolution stalagmite ba sed record of palaeoclim ate for northeastern South Africa. The Holocene, v. 9, pp. 295. Huschke, R.E., 1959. Glossary of Meteorology. Am erican Meteorological Society, 638 pp. Ingraham, N.L., 1998. Isotopic Variations in Precipitation. In Isotopic Tracers in Catchment Hydrology, Kendall, C. and McDonne ll, J.J. (eds.) Elsevier Science B.V., Amsterdam; pp. 87-118. Jones, I.C., Banner, J.L. and Humphrey J.D ., 2000. Estimating recharge in a tropical karst aquifer. Water Resources Research, v. 36, pp. 1289-1299. Kaufmann, G. and Dreybrodt, W., 2004. Stalagmite growth and paleo-climate: an inverse approach Earth and Planetary Science Letters, v. 224, pp. 529-545. Kim, S.T., and O'Neil, J.R., 1997. Equilibrium and non equilibrium oxygen isotope effects in synthetic carbonates. Geochimica et Cosmochimica Acta, v. 61, pp. 3461-3475. Kolodny, Y., Bar-Matthews, M., Ayalon, A., and McKeegan, K.D., 2002. A high spatial resolution profile of a speleothem using an ion-microprobe. Chemical Geology, v. 197, pp. 21-28.

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78 Labonne, M., Hillaire-Marcel, C., Ghaleb, B. and Goy, J.-L., 2002. Multi-isotopic age assessment of dirty speleothem calcite: an example from Altamira Cave, Spain. Quaternary Science Reviews, v. 21, pp. 1099-1110. Lachniet, M.S., Burns, S.J., Piperno, D.R., Asmerom, Y., Polyak, V.J., Moy, C.M., and Christenson, K., 2004. 1500-year El Nio/Sout hern oscillation and rainfall history for the Isthmus of Panama from spel eothem calcite. Journal of Geophysical Research, v. 109, pp. D20117. Lauritzen, S.E., and Lundberg, J., 1999a. Speleo thems and climate: a special issue of the Holocene. Holocene, v. 9, pp. 643-647. Lauritzen, S.E., and Lundberg, J., 1999. Calibrati on of the speleothem delta function; an absolute temperature record from the Holocene in northern Norway. Holocene, v. 9, pp. 659-669. Lauritzen, S-E., and Onac, B.P., 1999. Isotopic st ratigraphy of last interglacial stalagmite from northwestern Romania: correlation with deep-sea record and northernlatitude speleothem. Journal of Ca ve and Karst Studies, v. 61, pp. 22-30. Linge, H., Lauritzen, S.-E., Lundberg, J., Bers tad, I.M., 2001. Stable isotope stratigraphy of Holocene speleothems: examples from a cave system in Rana, northern Norway. Paleogeography, Paleoclimatology, Paleoecology, v. 167, pp. 209-224. Liu, K., Fearn, M.L., 2000. Reconstruction of prehistoric landfall frequencies of catastrophic hurricanes in northwestern Fl orida from lake sediment records. Quaternary Research, v. 54, pp. 238-245. Maddox, G.L., Lloyd, J.M., Scott, T.M., Lloyd, J.M. and Copeland, R., eds., 1991. Florida's ground-water quality monito ring program: Hydrological Framework. Florida Geological Survey Sp ecial Publication. no. 32, 97 pp. Mickler, P.J., Banner, J.L., Stern, L., As merom, Y., Edwards, R.L. and Ito, E., 2004. Stable isotope variations in modern tropical speleothems: Evaluating equilibrium vs. kinetic isotope effects. Geochimica et Cosmochimica Acta, v. 68, pp. 4381-4393. Miller, J. A., 1986. Hydrogeologic Framework of the Floridan Aquifer System in Florida and in Parts of Georgia, Alabama, and South Carolina, USGS Professional Paper 1403-B, 91pp.

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79 Physical Oceanography Division/NOAA. Retrieved October 29, 2005, from http://www.aoml.noaa.gov/phod/amo_faq.php#faq_1 Polyak, V. J., and Y. Asmerom, 2001.Late Ho locene climate and cultural changes in the southwestern United States. Science, v. 294, pp. 148. Poore, R.Z., Dowsett, H.J., Verardo, S., and Quinn, T.M., 2003. Millenialto centuryscale variability in Gulf og Mexico Ho locene climate records. Paleoceanography, v. 18, n. 2, 1048. Qin, X., Tan, M., Liu, T., Wang, X., Li, T., L u, J., 1999. Spectral analysis of a 1000-year stalagmite lamina thickness record from Shihua Cavern, Beijing, China, and its climatic significance. The Holocene, v. 9, pp. 689-694. Randazzo, A.F., and Jones, D.S., eds., 1997. The Geology of Florida: Gainesville, Florida University Press of Florida, 327 p. Reeder, P.P., Brinkmann, R., 1998. Paleoenvir onmental Reconstruction on an Oligocene Aged Island Remnant in Florida, USA. Cave and Karst Science. V. 25, pp. 7-13. Richards, D.A., Dorale, J.A., 2003, Uraniu m-series chronology and environmental applications of speleothems. In: Re views in Mineralogy and GeochemistryUranium-series Geochemistry. v. 52, pp. 407-460. Ruddiman, W.F., 2001. Earths Climate: Past and Future. W.H. Freeman and Company: New York, pp 150-155. Schwarcz, H.P., 1986. Geochronology and isot opic geochemistry of speleothems: in Fontes, J.C., & Fritz, P., (eds.) Handbook of environmental isotope geochemistry. The terrestrial environment, B: Elsevier, Amsterdam, pp. 271-303. Scott, T.M., 1988. The lithostr atigraphy of the Hawthorn Gr oup (Miocene) of Florida. Florida Geological Survey Bulletin, no. 59, p. 1-148. Serefiddin F., Schwarcz H.P., Ford D.C., Baldwin S., 2004. Late Pleistocene paleoclimate in the Black Hills of South Dakota from isotope records in speleothems. Palaeogeography, Palaeoclim atology, Palaeoecology, v. 203, pp. 1-17. South East Regional Climat e Center (SERCC). Retrieved February 21, 2005, from (http://cirrus.dnr.sta te.sc.us/cgi-bin/sercc/cliMAIN.pl?fl1046) Stahle, D.W., and Cleaveland, M.K., 1992. Recons truction and analysis of Spring rainfall over the Souteastern U.S. for the past 1000 years. Bulletin of the American Meteorological Society, v. 73, pp. 1947-1961.

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80 Tihansky, A. B., and Knochenmus, L. A., 2001. Karst Features and Hydrogeology in West-Central Florida--A Field Perspectiv e. In: U.S. Geological Survey Karst Interest Group Proceedings. (E.L. Kuniansky, editor).USGS Water-Resources Investigations Report 01-4011. Thompson, P., Schwarcz, H.P. and Ford, D. C., 1974. Continental Pleistocene climatic variations from speleothem age and isotopic data. Science, v. 184, pp. 893-895. Vaks, A., Bar-Matthews, M., Ayalon, A., Schilman, B., Gilmour, M., Hawkesworth, C. J., Frumkin, A., Kaufman, A., and Matthews, A., 2003. Paleoclimate reconstruction based on the timing of speleothem growth, oxygen and carbon isotope composition from a cave located in the 'rain shadow', Israel: Quaternary Research v. 59, pp. 182-193. van Beynen P.E., Ford, D.C., Schwarz, H., 2000. Seasonal variability in organic substances in surface and cave waters at Marengo Cave, Indiana. Hydrological Processes, v. 14, pp. 1177-1197. van Beynen, P.E., Schwarcz, H.P, and Ford, D.C., 2004. Holocene climatic variation recorded in a speleothem from McFails Cave, New York. Journal of Cave and Karst Studies, v. 66, no. 1, pp. 20-27. van Beynen, P.E., Cross, E., Van Vleet, T., Hollander, D., 2004. Denver Annual Meeting, Geological Society of America Abstracts with Programs, v. 36, no. 5, p. 90 Watts, W.A., and Hansen B. C. S., 1994. Pr e-Holocene and Holocen e pollen records of vegetation history from the Florida peninsula and their climate implications. Palaeogeography, Palaeoclimat ology, Palaeoecology, v. 109, pp. 163. Wigley, T.M.L. and Brown, M.C., 1976. The Physics of Caves., In The Science of Speleology, (Ford, T.D. and Cullingford, C.H.L., eds.). Academic Press: London; pp. 329-358. Winsberg, M., Solecki, W.D. and Walker, R., 1994.Rapidly changing land use in South Florida: measurement, problem, and so lution. Governing Florida, v. 4, pp. 23-28. White, W., 2004, Paleoclimate records from sp eleothem in limestone caves. In: Studies of Cave Sediments Physical and Chemi cal Records of Paleoclimate (Saskowski, I.and Mylroie, J., eds.), Klewer Academic/Plenum Publishers, New York. pp. 135-175. Yonge, C.J., Ford, D.C., Gray, J. and Schwarcz, H.P., 1985. Stable isotope studies of cave seepage water. Chemical Geology, v. 58, pp. 97-105.

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81 Yon, W.J. and Hendry, C.W., 1972. Suwann ee limestone in Hernando and Pasco Countries, Florida. Florida Department of Natural Resources, Division of Interior Resources, Bureau of Geology, Geological bulletin, no. 54, 71 p. Zhang, M., Yuan, D., Lin, Y., Qin, J.,Bin, L., Cheng, H., and Edwards, R.L., 2004. A 6000-year High-Resolution Climatic Record from a Stalagmite in Xiangshui Cave, Guilin, China. The Holocene, v. 14, no .5, pp. 697-702.

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82 Appendices

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83 Appendix A: BRC03-02 Stable Isotopic Results Sample Identification Distance from top (mm) 13 C (VPDB) 18 O (VPDB) Age (Years BP) BRCO3-2 1 -11.40 -4.55 0 BRCO3-2 2 -11.49 -4.60 32 BRCO3-2 3 -12.01 -4.38 63 BRCO3-2 4 -11.98 -4.34 95 BRCO3-2 5 -11.93 -4.49 126 BRCO3-2 6 -11.76 -4.52 158 BRCO3-2 7 -11.91 -4.64 189 BRCO3-2 8 -11.76 -4.63 221 BRCO3-2 9 -11.33 -4.39 252 BRCO3-2 10 -11.33 -4.23 284 BRCO3-2 11 -11.84 -4.36 315 BRCO3-2 12 -11.84 -4.36 347 BRCO3-2 13 -11.94 -4.39 361 BRCO3-2 14 -11.96 -4.25 375 BRCO3-2 15 -12.24 -4.46 390 BRCO3-2 16 -12.15 -4.71 404 BRCO3-2 17 -12.24 -4.92 418 BRCO3-2 18 -11.84 -4.53 432 BRCO3-2 19 -11.73 -4.45 447 BRCO3-2 20 -12.25 -4.72 461 BRCO3-2 21 -12.04 -4.42 475 BRCO3-2 22 -12.11 -4.61 477 BRCO3-2 23 -12.15 -4.88 479 BRCO3-2 24 -12.07 -4.31 482 BRCO3-2 25 -12.14 -5.02 484 BRCO3-2 26 -12.09 -4.97 486 BRCO3-2 27 -11.97 -4.87 488 BRCO3-2 28 -11.90 -4.61 491 BRCO3-2 29 -11.75 -4.63 493 BRCO3-2 30 -11.87 -4.85 495 BRCO3-2 31 -11.73 -4.84 497 BRCO3-2 32 -11.79 -4.70 500 BRCO3-2 33 -11.88 -4.79 502 BRCO3-2 34 -12.07 -4.96 504 BRCO3-2 35 -12.08 -5.01 506 BRCO3-2 36 -12.14 -5.00 508 BRCO3-2 37 -12.12 -4.87 511 BRCO3-2 38 -12.09 -4.97 513 BRCO3-2 39 -11.78 -4.79 515 BRCO3-3 40 -12.01 -4.85 517 BRCO3-2 41 -11.98 -4.79 520 BRCO3-2 42 -12.10 -4.70 522 BRCO3-2 43 -12.16 -4.66 524

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84 Appendix A:(Continued) BRCO3-2 44 -12.24 -4.57 538 BRCO3-2 45 -12.15 -4.45 552 BRCO3-2 46 -12.21 -4.39 566 BRCO3-2 47 -12.18 -4.41 580 BRCO3-2 48 -12.26 -4.55 594 BRCO3-2 49 -12.07 -4.48 608 BRCO3-2 50 -12.25 -4.66 622 BRCO3-2 51 -12.19 -4.51 636 BRCO3-2 52 -12.19 -4.65 650 BRCO3-2 53 -12.23 -4.60 665 BRCO3-2 54 -12.18 -4.64 679 BRCO3-2 55 -12.25 -4.55 693 BRCO3-2 56 -12.03 -4.35 707 BRCO3-2 57 -12.42 -4.49 721 BRCO3-2 58 -12.26 -4.52 735 BRCO3-2 59 -12.25 -4.50 749 BRCO3-2 60 -12.24 -4.40 763 BRCO3-2 61 -12.24 -4.47 777 BRCO3-2 62 -12.35 -4.53 791 BRCO3-2 63 -12.02 -4.52 805 BRCO3-2 64 -12.18 -4.55 816 BRCO3-2 65 -12.15 -4.47 827 BRCO3-2 66 -12.32 -4.72 837 BRCO3-2 67 -12.26 -4.93 848 BRCO3-2 68 -12.18 -5.19 859 BRCO3-2 69 -12.21 -5.10 870 BRCO3-2 70 -12.09 -4.79 880 BRCO3-2 71 -12.02 -4.72 891 BRCO3-2 72 -11.65 -4.71 902 BRCO3-2 73 -11.94 -4.80 913 BRCO3-2 74 -12.11 -5.25 924 BRCO3-2 75 -12.20 -5.09 934 BRCO3-2 76 -12.16 -5.24 945 BRCO3-2 77 -12.21 -4.95 956 BRCO3-2 78 -11.93 -4.60 967 BRCO3-2 79 -11.95 -4.64 977 BRCO3-2 80 -12.21 -4.75 988 BRCO3-2 81 -12.33 -4.61 999 BRCO3-2 82 -12.56 -4.94 1010 BRCO3-2 83 -12.57 -5.15 1021 BRCO3-2 84 -12.48 -4.93 1031 BRCO3-2 85 -12.46 -4.99 1042 BRCO3-2 86 -12.42 -5.03 1053 BRCO3-2 87 -12.27 -4.79 1064 BRCO3-2 88 -12.40 -5.08 1074

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85 Appendix A:(Continued) BRCO3-2 89 -11.97 -4.88 1085 BRCO3-2 90 -12.12 -4.75 1096 BRCO3-2 91 -11.98 -4.67 1107 BRCO3-2 92 -11.96 -4.73 1117 BRCO3-2 93 -11.64 -4.82 1128 BRCO3-2 94 -11.78 -4.64 1139 BRCO3-2 95 -11.68 -4.70 1150 BRCO3-2 96 -11.98 -4.61 1161 BRCO3-2 97 -12.04 -4.90 1171 BRCO3-2 98 -12.04 -4.67 1182 BRCO3-2 99 -12.16 -4.66 1193 BRCO3-3 100 -12.19 -4.70 1204 BRCO3-2 101 -12.22 -4.73 1214 BRCO3-2 102 -12.18 -4.49 1225 BRCO3-2 103 -12.34 -4.34 1236 BRCO3-2 104 -12.34 -4.25 1244 BRCO3-2 105 -12.54 -4.42 1251 BRCO3-2 106 -12.35 -4.37 1259 BRCO3-2 107 -12.43 -4.52 1266 BRCO3-2 108 -12.34 -4.46 1273 BRCO3-2 109 -12.36 -4.65 1281 BRCO3-2 110 -12.32 -4.77 1288 BRCO3-2 111 -12.10 -4.74 1296 BRCO3-2 112 -12.02 -4.66 1303 BRCO3-2 113 -12.12 -4.65 1310 BRCO3-2 114 -12.21 -4.71 1318 BRCO3-2 115 -11.94 -4.70 1325 BRCO3-2 116 -11.96 -4.53 1333 BRCO3-2 117 -11.88 -4.40 1340 BRCO3-2 118 -12.07 -4.43 1347 BRCO3-2 119 -11.93 -4.29 1355 BRCO3-2 120 -12.06 -4.30 1362 BRCO3-2 121 -12.03 -4.10 1370 BRCO3-2 122 -11.81 -4.55 1377 BRCO3-2 123 -12.16 -4.36 1411 BRCO3-2 124 -11.88 -4.27 1445 BRCO3-2 125 -11.79 -4.32 1479 BRCO3-2 126 -11.63 -4.43 1514 BRCO3-2 127 -11.54 -4.39 1548 BRCO3-2 128 -11.34 -4.26 1582

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86 Appendix A:(Continued) BRCO3-2 129 -11.50 -4.35 1616 BRCO3-2 130 -11.59 -4.30 1650 BRCO3-2 131 -11.71 -4.32 1684 BRCO3-2 132 -11.91 -4.43 1718 BRCO3-2 133 -12.05 -4.36 1753 BRCO3-2 134 -12.10 -4.40 1787 BRCO3-2 135 -12.11 -4.28 1821 BRCO3-2 136 -11.91 -4.31 1855 BRCO3-2 137 -11.08 -4.39 1900 BRCO3-2 138 -11.38 -4.40 1945 BRCO3-2 139 -11.59 -4.37 1989 BRCO3-2 140 -11.60 -4.77 2034 BRCO3-2 141 -11.91 -4.77 2079 BRCO3-2 142 -11.98 -4.59 2124 BRCO3-2 143 -11.85 -4.40 2168 BRCO3-2 144 -11.78 -4.46 2213 BRCO3-2 145 -11.88 -4.38 2258 BRCO3-2 146 -11.68 -4.27 2303 BRCO3-2 147 -11.36 -4.01 2347 BRCO3-2 148 -11.12 -3.94 2392 BRCO3-2 149 -11.22 -4.10 2437 BRCO3-2 150 -11.58 -4.22 2482 BRCO3-2 151 -11.89 -4.22 2526 BRCO3-2 152 -11.90 -3.97 2571

PAGE 96

87 Appendix B: BRC03-03 Stable Isotopic Results Sample Identification (mm) Distance from top (mm) 13 C (VPDB) 18 O (VPDB) Age (Years BP) BRC03-03 0 -10.48 -3.76 3,968 BRC03-03 1 -10.40 -3.68 3,984 BRC03-03 2 -10.63 -3.64 3,999 BRC03-03 3 -10.86 -3.43 4,014 BRC03-03 4 -9.88 -3.54 4,030 BRC03-03 5 -10.30 -3.72 4,045 BRC03-03 6 -10.29 -3.77 4,061 BRC03-03 7 -10.12 -3.62 4,076 BRC03-03 8 -10.20 -3.40 4,091 BRC03-03 9 -9.23 -3.63 4,107 BRC03-03 10 -9.01 -3.25 4,122 BRC03-03 11 -9.89 -3.35 4,138 BRC03-03 12 -10.13 -3.13 4,153 BRC03-03 13 -9.95 -3.12 4,168 BRC03-03 14 -10.02 -3.24 4,184 BRC03-03 15 -9.99 -3.33 4,199 BRC03-03 16 -9.68 -3.33 4,215 BRC03-03 17 -9.37 -3.63 4,230 BRC03-03 18 -9.91 -4.08 4,245 BRC03-03 19 -10.03 -4.17 4,261 BRC03-03 20 -9.76 -3.63 4,276 BRC03-03 21 -9.64 -3.65 4,292 BRC03-03 22 -10.00 -3.65 4,307 BRC03-03 23 -9.86 -3.67 4,322 BRC03-03 24 -9.33 -3.42 4,338 BRC03-03 25 -10.82 -3.66 4,353 BRC03-03 26 -11.11 -4.08 4,369 BRC03-03 27 -11.00 -3.88 4,384 BRC03-03 28 -11.03 -3.95 4,399 BRC03-03 29 -10.18 -3.74 4,415 BRC03-03 30 -10.21 -3.75 4,430 BRC03-03 31 -10.78 -3.98 4,446 BRC03-03 32 -10.28 -3.78 4,461 BRC03-03 33 -10.70 -3.74 4,516 BRC03-03 34 -10.54 -3.90 4,544 BRC03-03 35 -9.22 -3.34 4,572 BRC03-03 36 -10.47 -3.53 4,600

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88 Appendix B: (Continued) BRC03-03 37 -10.08 -3.81 4,627 BRC03-03 38 -10.65 -4.05 4,655 BRC03-03 39 -10.60 -3.86 4,683 BRC03-03 40 -10.53 -3.53 4,710 BRC03-03 41 -9.74 -3.20 4,738 BRC03-03 42 -9.64 -3.58 4,746 BRC03-03 43 -10.10 -3.42 4,755 BRC03-03 44 -9.95 -3.49 4,763 BRC03-03 45 -9.75 -3.50 4,772 BRC03-03 46 -8.97 -3.15 4,780 BRC03-03 47 -9.06 -3.04 4,788 BRC03-03 48 -9.28 -3.57 4,797 BRC03-03 49 -8.71 -3.22 4,805 BRC03-03 50 -9.17 -3.51 4,814 BRC03-03 51 -9.02 -3.37 4,822 BRC03-03 52 -9.01 -3.38 4,830 BRC03-03 53 -10.02 -3.77 4,839 BRC03-03 54 -10.53 -3.79 4,847 BRC03-03 55 -10.42 -3.64 4,855 BRC03-03 56 -10.60 -3.70 4,864 BRC03-03 57 -10.66 -3.76 4,872 BRC03-03 58 -10.67 -3.76 4,881 BRC03-03 59 -10.33 -3.72 4,889 BRC03-03 60 -10.23 -3.49 4,897 BRC03-03 61 -9.55 -3.47 4,906 BRC03-03 62 -9.58 -3.31 4,914 BRC03-03 63 -10.57 -3.52 4,923 BRC03-03 64 -10.75 -3.55 4,931 BRC03-03 65 -10.59 -2.91 4,950 BRC03-03 66 -10.84 -3.60 4,969 BRC03-03 67 -10.60 -3.52 4,989 BRC03-03 68 -10.68 -3.91 5,008 BRC03-03 69 -11.10 -4.36 5,027 BRC03-03 70 -10.13 -3.77 5,046 BRC03-03 71 -10.39 -3.17 5,066 BRC03-03 73 -10.16 -3.75 5,085 BRC03-03 74 -10.56 -4.07 5,104 BRC03-03 75 -10.42 -3.73 5,123 BRC03-03 76 -10.34 -3.24 5,142 BRC03-03 77 -10.52 -3.86 5,162 BRC03-03 78 -10.07 -3.21 5,181 BRC03-03 79 -8.70 -3.17 *5,200 BRC03-03 80 -8.49 -2.56 n/a BRC03-03 81 -6.55 -1.95 n/a BRC03-03 82 -5.85 -2.04 21,078 BRC03-03 83 -6.84 -2.58 21,195

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89 Appendix B: (Continued) BRC03-03 84 -7.16 -2.68 21,312 BRC03-03 85 -6.24 -2.39 21,429 BRC03-03 86 -6.14 -2.30 21,547 BRC03-03 87 -6.88 -2.47 21,664 BRC03-03 88 -7.96 -2.89 21,781 BRC03-03 89 -8.60 -3.26 21,898 BRC03-03 90 -7.98 -2.91 22,015 BRC03-03 91 -9.37 -2.91 22,132 BRC03-03 92 -8.04 -3.26 22,249 BRC03-03 93 -9.07 -2.65 22,366 BRC03-03 94 -8.87 -2.80 22,483 BRC03-03 95 -9.31 -2.76 22,600 BRC03-03 96 -9.32 -3.17 22,718 BRC03-03 97 -9.05 -2.66 22,835 BRC03-03 98 -9.30 -2.51 22,952 BRC03-03 99 -9.12 -2.59 23,069 BRC03-03 100 -8.86 -2.44 23,186 BRC03-03 101 -9.13 -2.45 23,303 BRC03-03 102 -9.11 -2.26 23,420 BRC03-03 103 -9.09 -2.32 23,537 BRC03-03 104 -9.20 -2.59 23,654 BRC03-03 105 -9.19 -2.60 23,771 BRC03-03 106 -9.93 -3.31 23,889 BRC03-03 107 -10.01 -3.42 24,006 BRC03-03 108 -9.93 -3.34 24,123 BRC03-03 109 -9.85 -3.28 24,240 BRC03-03 110 -9.15 -2.87 24,357 BRC03-03 111 -7.95 -2.16 24,474 BRC03-03 112 -7.71 -2.08 24,595 BRC03-03 113 -7.40 -1.85 24,717 BRC03-03 114 -6.83 -1.79 24,838 BRC03-03 116 -8.58 -2.85 24,959 BRC03-03 117 -7.38 -2.50 25,081 BRC03-03 118 -5.27 -1.69 25,202 BRC03-03 119 -4.75 -1.72 25,324 BRC03-03 120 -5.34 -1.86 25,445 BRC03-03 121 -5.24 -1.89 25,566 BRC03-03 122 -6.34 -2.24 25,688 BRC03-03 123 -6.90 -2.73 25,809 BRC03-03 124 -7.03 -2.53 25,930 BRC03-03 125 -7.32 -2.92 26,052 BRC03-03 126 -7.01 -2.19 26,173 BRC03-03 127 -7.78 -2.48 26,294 BRC03-03 128 -6.86 -2.07 26,416 BRC03-03 129 -8.64 -2.77 26,537 BRC03-03 130 -9.17 -2.34 26,682

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90 Appendix B: (Continued) BRC03-03 131 -9.35 -2.69 26,827 BRC03-03 132 -8.16 -2.58 26,971 BRC03-03 133 -8.18 -2.56 27,116 BRC03-03 134 -7.33 -2.33 27,261 BRC03-03 135 -7.41 -2.37 27,406 BRC03-03 136 -8.43 -2.63 27,550 BRC03-03 137 -8.20 -2.54 27,695 BRC03-03 138 -8.22 -2.53 27,840 BRC03-03 139 -6.90 -2.72 27,985 BRC03-03 140 -7.67 -2.81 28,129 BRC03-03 141 -7.24 -2.75 28,274 BRC03-03 142 -8.42 -2.80 28,419 BRC03-03 143 -8.04 -2.70 28,564 BRC03-03 144 -8.30 -3.00 28,708 BRC03-03 145 -8.47 -3.24 28,853 BRC03-03 146 -8.29 -3.09 28,998 BRC03-03 147 -8.48 -3.29 28,999 BRC03-03 148 -8.15 -3.01 28,999 BRC03-03 149 -8.38 -3.03 29,000 BRC03-03 150 -8.21 -2.93 29,001 BRC03-03 151 -8.34 -3.09 29,002 BRC03-03 152 -7.84 -2.77 29,003 BRC03-03 153 -8.15 -3.02 29,003 BRC03-03 154 -7.81 -2.73 29,004 BRC03-03 155 -7.86 -2.82 29,005 BRC03-03 156 -8.18 -3.01 29,006 BRC03-03 157 -7.94 -2.63 29,007 BRC03-03 158 -7.97 -2.65 29,007 BRC03-03 159 -8.00 -2.75 29,008 BRC03-03 160 -7.98 -2.60 29,009 BRC03-03 161 -7.96 -2.94 29,010 BRC03-03 162 -7.52 -2.58 29,011 BRC03-03 163 -7.52 -2.52 29,011 BRC03-03 164 -7.52 -2.72 29,012 BRC03-03 165 -7.64 -2.95 29,013 BRC03-03 166 -7.09 -2.95 29,023 BRC03-03 167 -7.34 -3.45 29,032 BRC03-03 168 -7.28 -3.05 29,042 BRC03-03 169 -6.91 -2.75 29,051 BRC03-03 170 -7.27 -2.93 29,061 BRC03-03 171 -7.24 -2.79 29,070 BRC03-03 172 -7.23 -2.84 29,080 BRC03-03 173 -7.18 -2.71 29,089 BRC03-03 174 -7.84 -3.44 29,099 BRC03-03 175 -7.31 -2.79 29,108 BRC03-03 176 -7.58 -2.87 29,118

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91 Appendix B: (Continued) BRC03-03 177 -7.50 -2.89 29,127 BRC03-03 178 -7.93 -3.11 29,137 BRC03-03 179 -8.01 -3.23 29,146 BRC03-03 180 -7.94 -3.09 29,156 BRC03-03 181 -7.94 -2.97 29,165 BRC03-03 182 -8.30 -3.25 29,175 BRC03-03 183 -8.48 -3.39 29,184 BRC03-03 184 -8.60 -3.07 29,194 BRC03-03 185 -8.23 -3.27 29,203 BRC03-03 186 -7.73 -2.85 29,213 BRC03-03 187 -6.37 -2.26 29,222 BRC03-03 188 -6.79 -2.59 29,232 BRC03-03 189 -6.90 -2.72 29,241 Interpolated date

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92 Appendix C: BRIARS04-01 St able Isotopic Analysis Sample Identification Distance from top (mm) 13 C (VPDB) 18 O (VPDB) Age (Years BP) BRIARS04-01 0 -6.49 -3.91 1074 BRIARS04-01 1 -6.10 -3.78 1088 BRIARS04-01 2 -7.12 -3.95 1101 BRIARS04-01 3 -6.98 -4.15 1115 BRIARS04-01 4 -6.78 -3.65 1128 BRIARS04-01 5 -6.21 -3.29 1142 BRIARS04-01 6 -6.13 -3.70 1156 BRIARS04-01 7 -5.80 -3.60 1169 BRIARS04-01 8 -5.47 -3.50 1183 BRIARS04-01 9 -5.65 -3.56 1196 BRIARS04-01 10 -5.84 -3.62 1210 BRIARS04-01 11 -5.33 -3.83 1224 BRIARS04-01 12 n/a n/a 1237 BRIARS04-01 13 n/a n/a 1251 BRIARS04-01 14 n/a n/a 1264 BRIARS04-01 15 n/a n/a 1278 BRIARS04-01 16 -6.68 -3.61 1292 BRIARS04-01 17 n/a n/a 1305 BRIARS04-01 18 n/a n/a 1319 BRIARS04-01 19 n/a n/a 1332 BRIARS04-01 20 n/a n/a 1346 BRIARS04-01 21 n/a n/a 1360 BRIARS04-01 22 n/a n/a 1373 BRIARS04-01 23 n/a n/a 1387 BRIARS04-01 24 n/a n/a 1400 BRIARS04-01 25 n/a n/a 1414 BRIARS04-01 26 -5.85 -4.06 1428 BRIARS04-01 27 -6.28 -4.17 1441 BRIARS04-01 28 -6.71 -4.28 1455 BRIARS04-01 29 -7.21 -4.42 1468 BRIARS04-01 30 -7.63 -3.81 1482 BRIARS04-01 31 -8.24 -4.02 1503 BRIARS04-01 32 -7.51 -4.22 1524 BRIARS04-01 33 -7.31 -4.00 1544 BRIARS04-01 34 -8.47 -4.77 1565 BRIARS04-01 35 -8.48 -4.95 1586

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93 Appendix C: (Continued) BRIARS04-01 36 -7.97 -4.12 1607 BRIARS04-01 37 -7.69 -4.04 1628 BRIARS04-01 38 -7.62 -4.19 1648 BRIARS04-01 39 -8.38 -5.02 1669 BRIARS04-01 40 -8.26 -4.72 1690 BRIARS04-01 41 -8.14 -4.42 1711 BRIARS04-01 42 -8.40 -4.51 1732 BRIARS04-01 43 -8.47 -4.41 1752 BRIARS04-01 44 -8.20 -4.15 1773 BRIARS04-01 45 -8.19 -4.50 1794 BRIARS04-01 46 -8.65 -4.69 1802 BRIARS04-01 47 -7.84 -3.99 1811 BRIARS04-01 48 -8.17 -3.98 1819 BRIARS04-01 49 -8.10 -3.88 1827 BRIARS04-01 50 -8.55 -3.95 1835 BRIARS04-01 51 -8.55 -4.23 1844 BRIARS04-01 52 -8.31 -4.03 1852 BRIARS04-01 53 -8.20 -4.61 1860 BRIARS04-01 54 -8.39 -4.30 1869 BRIARS04-01 55 -8.17 -4.36 1877 BRIARS04-01 56 -8.25 -4.17 1885 BRIARS04-01 57 -8.20 -4.24 1893 BRIARS04-01 58 -7.99 -4.33 1902 BRIARS04-01 59 -8.41 -4.41 1910 BRIARS04-01 60 -8.46 -4.59 1918 BRIARS04-01 61 -8.03 -4.52 1926 BRIARS04-01 62 -7.74 -3.94 1935 BRIARS04-01 63 -8.03 -4.00 1943 BRIARS04-01 64 -8.31 -4.06 1955 BRIARS04-01 65 -8.24 -4.12 1966 BRIARS04-01 66 -8.59 -4.18 1978 BRIARS04-01 67 -8.45 -3.80 1989 BRIARS04-01 68 -9.29 -3.95 2001 BRIARS04-01 69 -9.02 -4.00 2013 BRIARS04-01 70 -8.93 -3.88 2024 BRIARS04-01 71 -8.94 -4.17 2036 BRIARS04-01 72 -8.93 -4.10 2047 BRIARS04-01 73 -8.66 -4.10 2059 BRIARS04-01 74 -8.42 -4.25 2070 BRIARS04-01 75 -8.63 -4.59 2082 BRIARS04-01 76 -8.98 -4.66 2094 BRIARS04-01 77 -9.32 -4.41 2105 BRIARS04-01 78 -9.48 -4.24 2117 BRIARS04-01 79 -7.23 -3.68 2128 BRIARS04-01 80 -9.69 -4.57 2140

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94 Appendix C: (Continued) BRIARS04-01 81 -9.27 -4.54 2151 BRIARS04-01 82 -8.76 -4.09 2163 BRIARS04-01 83 -8.33 -4.39 2176 BRIARS04-01 84 -8.18 -4.46 2188 BRIARS04-01 85 -7.81 -4.34 2200 BRIARS04-01 86 -7.57 -4.14 2213 BRIARS04-01 87 -7.78 -4.05 2225 BRIARS04-01 88 -8.01 -4.03 2237 BRIARS04-01 89 -7.99 -4.05 2250 BRIARS04-01 90 -7.85 -3.91 2262 BRIARS04-01 91 -7.75 -3.83 2274 BRIARS04-01 92 -7.60 -4.57 2287 BRIARS04-01 93 -7.31 -4.37 2299 BRIARS04-01 94 -7.69 -4.27 2311 BRIARS04-01 95 -8.14 -4.08 2324 BRIARS04-01 96 -8.34 -4.32 2336 BRIARS04-01 97 -8.45 -4.38 2348 BRIARS04-01 98 -8.27 -3.83 2361 BRIARS04-01 99 -7.98 -3.88 2373 BRIARS04-01 100 -7.14 -3.59 2385 BRIARS04-01 101 -7.16 -4.02 2398 BRIARS04-01 102 -7.57 -4.28 2410 BRIARS04-01 103 -7.38 -4.05 2423 BRIARS04-01 104 -7.72 -4.22 2435 BRIARS04-01 105 -7.81 -4.22 2447 BRIARS04-01 106 -7.51 -4.21 2460 BRIARS04-01 107 -8.35 -3.99 2472 BRIARS04-01 108 -8.69 -4.15 2484 BRIARS04-01 109 -8.82 -4.12 2497 BRIARS04-01 110 -8.24 -3.89 2509 BRIARS04-01 111 -8.62 -4.11 2521 BRIARS04-01 112 -9.31 -4.59 2534 BRIARS04-01 113 -9.14 -4.47 2546 BRIARS04-01 114 -8.88 -4.43 2587 BRIARS04-01 115 -8.63 -4.39 2628 BRIARS04-01 116 -8.36 -4.29 2669 BRIARS04-01 117 -8.11 -4.19 2710 BRIARS04-01 118 -6.91 -4.01 2751 BRIARS04-01 119 -6.17 -3.71 2792 BRIARS04-01 120 -8.19 -4.31 2832 BRIARS04-01 121 -8.53 -4.20 2873 BRIARS04-01 122 -8.66 -4.36 2914 BRIARS04-01 123 -8.52 -4.31 2955 BRIARS04-01 124 n/a n/a 2996 BRIARS04-01 125 n/a n/a 3037

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95 Appendix C: (Continued) BRIARS04-01 126 -8.81 -4.12 3078 BRIARS04-01 127 -9.02 -4.37 3119 BRIARS04-01 128 -9.23 -4.63 3159 BRIARS04-01 129 -9.16 -4.44 3200 BRIARS04-01 130 -9.09 -4.25 3241 BRIARS04-01 131 -8.89 -4.37 3282 BRIARS04-01 132 -8.37 -4.31 3323 BRIARS04-01 133 -7.93 -4.38 3364 BRIARS04-01 134 -7.59 -4.81 3405 BRIARS04-01 135 -7.37 -4.43 3446 BRIARS04-01 136 -7.16 -4.05 3486 BRIARS04-01 137 -7.72 -4.48 3527 BRIARS04-01 138 n/a n/a 3568 BRIARS04-01 139 n/a n/a 3609 BRIARS04-01 140 -8.01 -4.40 3650

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96 Appendix D: BRIARS04-02 Stab le Isotopic Analysis Sample Identification Distance from top (mm) 13 C (VPDB) 18 O (VPDB) Age (Years BP) BRIARS04-02 1 -10.03 -5.95 0 BRIARS04-02 2 -10.57 -4.56 1 BRIARS04-02 3 -10.15 -4.64 2 BRIARS04-02 4 -10.49 -4.64 2 BRIARS04-02 5 -10.61 -4.97 3 BRIARS04-02 6 -10.22 -4.87 4 BRIARS04-02 7 -9.88 -5.07 5 BRIARS04-02 8 -10.04 -4.41 5 BRIARS04-02 9 -10.27 -4.26 6 BRIARS04-02 10 -10.18 -4.18 7 BRIARS04-02 11 -9.86 -4.40 8 BRIARS04-02 12 -9.75 -4.37 8 BRIARS04-02 13 -9.99 -4.76 9 BRIARS04-02 14 -10.20 -5.25 10 BRIARS04-02 15 -10.44 -5.12 11 BRIARS04-02 16 -10.18 -4.81 11 BRIARS04-02 17 -10.01 -4.55 12 BRIARS04-02 18 -8.75 -4.20 13 BRIARS04-02 19 -9.62 -5.16 14 BRIARS04-02 20 -9.30 -4.78 15 BRIARS04-02 21 -9.77 -5.15 15 BRIARS04-02 22 -9.38 -5.15 16 BRIARS04-02 23 -9.31 -4.73 17 BRIARS04-02 24 -9.71 -4.63 18 BRIARS04-02 25 -9.93 -4.33 18 BRIARS04-02 26 -9.76 -4.77 19 BRIARS04-02 27 -9.76 -4.33 20 BRIARS04-02 28 -9.88 -4.45 21 BRIARS04-02 29 -9.97 -5.02 21 BRIARS04-02 30 -9.92 -4.65 22 BRIARS04-02 31 -9.98 -5.27 23 BRIARS04-02 32 -9.85 -4.81 24 BRIARS04-02 33 -9.80 -4.95 24 BRIARS04-02 34 -9.74 -5.13 25 BRIARS04-02 35 -9.26 -4.93 26 BRIARS04-02 36 -9.75 -4.97 27 BRIARS04-02 37 -9.73 -4.93 27 BRIARS04-02 38 -9.68 -4.70 28 BRIARS04-02 39 -9.65 -5.44 29 BRIARS04-02 40 -9.76 -4.75 30 BRIARS04-02 41 -9.62 -4.66 30 BRIARS04-02 42 -8.59 -4.30 31

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97 Appendix D: (Continued) BRIARS04-02 43 -9.85 -5.11 32 BRIARS04-02 44 -9.36 -4.24 54 BRIARS04-02 45 -9.56 -4.52 77 BRIARS04-02 46 -9.28 -3.90 99 BRIARS04-02 47 -9.43 -3.84 122 BRIARS04-02 48 -9.59 -4.62 144 BRIARS04-02 49 -9.94 -5.70 166 BRIARS04-02 50 -9.22 -4.53 189 BRIARS04-02 51 -9.69 -5.35 211 BRIARS04-02 52 -9.71 -4.76 234 BRIARS04-02 53 -9.56 -4.83 256 BRIARS04-02 54 -9.09 -4.07 278 BRIARS04-02 55 -9.53 -4.88 301 BRIARS04-02 56 -9.03 -4.45 323 BRIARS04-02 57 -9.54 -5.50 346 BRIARS04-02 58 -9.28 -4.50 368 BRIARS04-02 59 -9.59 -4.75 390 BRIARS04-02 60 -9.01 -4.60 413 BRIARS04-02 61 -8.67 -4.56 435 BRIARS04-02 62 -8.61 -4.26 458 BRIARS04-02 63 -8.69 -4.19 480 BRIARS04-02 64 -9.17 -3.58 480 BRIARS04-02 65 -9.10 -4.66 486 BRIARS04-02 66 -9.08 -4.93 492 BRIARS04-02 67 -8.44 -3.60 498 BRIARS04-02 68 -8.78 -4.95 503 BRIARS04-02 69 -8.72 -4.62 509 BRIARS04-02 70 -9.01 -4.48 515 BRIARS04-02 71 -9.78 -5.38 521 BRIARS04-02 72 -9.81 -5.16 527 BRIARS04-02 73 -9.61 -4.49 533 BRIARS04-02 74 -9.57 -4.68 538 BRIARS04-02 75 -9.45 -4.41 544 BRIARS04-02 76 -9.65 -5.16 550 BRIARS04-02 77 -9.64 -4.78 556 BRIARS04-02 78 -9.70 -4.60 562 BRIARS04-02 79 -10.01 -4.70 568 BRIARS04-02 80 -10.31 -5.23 573 BRIARS04-02 81 -10.12 -4.51 579 BRIARS04-02 82 -9.92 -4.39 585

PAGE 107

98 Appendix D: (Continued) BRIARS04-02 83 -10.03 -4.52 591 BRIARS04-02 84 -9.92 -4.97 601 BRIARS04-02 85 -10.41 -5.74 611 BRIARS04-02 86 -10.10 -4.34 621 BRIARS04-02 87 -9.81 -4.35 631 BRIARS04-02 88 -9.65 -4.07 641 BRIARS04-02 89 -9.95 -4.91 651 BRIARS04-02 90 -9.22 -4.18 661 BRIARS04-02 91 -9.11 -4.63 671 BRIARS04-02 92 -9.28 -4.41 681 BRIARS04-02 93 -9.29 -4.44 691 BRIARS04-02 94 -9.50 -4.26 701 BRIARS04-02 95 -9.52 -4.65 711 BRIARS04-02 96 -9.69 -4.97 722 BRIARS04-02 97 -9.87 -5.29 732 BRIARS04-02 98 -9.63 -4.99 742 BRIARS04-02 99 -9.38 -4.69 752 BRIARS04-02 100 -9.43 -5.19 762 BRIARS04-02 101 -9.47 -5.69 772 BRIARS04-02 102 -9.45 -5.24 782 BRIARS04-02 103 -9.43 -4.78 792 BRIARS04-02 104 -9.54 -4.58 802 BRIARS04-02 105 -9.65 -4.37 812 BRIARS04-02 106 -10.10 -5.27 822 BRIARS04-02 107 -10.55 -6.17 832 BRIARS04-02 108 -10.22 -5.28 842 BRIARS04-02 109 -9.90 -4.39 860 BRIARS04-02 110 -9.78 -4.26 877 BRIARS04-02 111 -9.66 -4.12 895 BRIARS04-02 112 -9.82 -5.09 912 BRIARS04-02 113 -9.99 -6.05 930 BRIARS04-02 114 -10.14 -5.93 947 BRIARS04-02 115 -10.30 -5.81 965 BRIARS04-02 116 -10.08 -5.49 982 BRIARS04-02 117 -9.87 -5.18 1000 BRIARS04-02 118 -9.86 -5.13 1017 BRIARS04-02 119 -9.85 -5.08 1035 BRIARS04-02 120 -9.99 -5.97 1052 BRIARS04-02 121 -9.62 -5.11 1070 BRIARS04-02 122 -9.63 -5.70 1087 BRIARS04-02 123 -9.50 -5.09 1105 BRIARS04-02 124 -9.51 -5.24 1122 BRIARS04-02 125 -9.52 -5.39 1140 BRIARS04-02 126 -9.13 -4.35 1157 BRIARS04-02 127 -9.39 -4.67 1175 BRIARS04-02 128 -9.48 -4.97 1192

PAGE 108

99 Appendix D: (Continued) BRIARS04-02 129 -9.74 -5.10 1199 BRIARS04-02 130 -9.50 -4.55 1205 BRIARS04-02 131 -9.49 -4.60 1211 BRIARS04-02 132 -9.49 -4.66 1217 BRIARS04-02 133 -9.63 -4.84 1223 BRIARS04-02 134 -8.93 -4.77 1229 BRIARS04-02 135 -9.93 -5.23 1235 BRIARS04-02 136 -10.09 -5.12 1241 BRIARS04-02 137 -10.21 -5.22 1247 BRIARS04-02 138 -10.18 -4.77 1253 BRIARS04-02 139 -10.58 -4.79 1259 BRIARS04-02 140 -10.49 -4.64 1265 BRIARS04-02 141 -10.09 -4.84 1271 BRIARS04-02 142 -10.09 -5.00 1277 BRIARS04-02 143 -10.33 -5.28 1283 BRIARS04-02 144 -10.27 -5.32 1285 BRIARS04-02 145 -10.25 -5.05 1287 BRIARS04-02 146 -10.24 -4.79 1289 BRIARS04-02 147 -10.07 -4.66 1291 BRIARS04-02 148 -10.31 -5.75 1293 BRIARS04-02 149 -10.18 -4.90 1295 BRIARS04-02 150 -10.35 -4.75 1296 BRIARS04-02 151 -10.47 -4.78 1298 BRIARS04-02 152 -10.47 -4.61 1300 BRIARS04-02 153 -10.68 -5.07 1302 BRIARS04-02 154 -11.17 -6.05 1304 BRIARS04-02 155 -10.58 -5.11 1306 BRIARS04-02 156 -10.47 -4.69 1308 BRIARS04-02 157 -10.61 -4.81 1310 BRIARS04-02 158 -10.21 -4.52 1312 BRIARS04-02 159 -10.13 -4.64 1314 BRIARS04-02 160 -10.05 -4.67 1315 BRIARS04-02 161 -9.86 -4.86 1317 BRIARS04-02 162 -9.95 -5.32 1319 BRIARS04-02 163 -9.89 -5.44 1321 BRIARS04-02 164 -9.58 -5.31 1323 BRIARS04-02 165 -9.52 -5.18 1325 BRIARS04-02 166 -9.34 -4.72 1327 BRIARS04-02 167 -9.40 -4.87 1329 BRIARS04-02 168 -9.33 -4.70 1331 BRIARS04-02 169 -9.32 -4.52 1333 BRIARS04-02 170 -9.66 -4.79 1334 BRIARS04-02 171 -9.57 -4.61 1336 BRIARS04-02 172 -9.67 -4.70 1338 BRIARS04-02 173 -9.01 -4.48 1340 BRIARS04-02 174 -9.43 -4.62 1342

PAGE 109

100 Appendix D: (Continued) BRIARS04-02 175 -9.72 -4.47 1344 BRIARS04-02 176 -9.41 -4.67 1346 BRIARS04-02 177 -9.50 -4.85 1366 BRIARS04-02 178 -10.00 -5.01 1386 BRIARS04-02 179 -10.40 -4.62 1406 BRIARS04-02 180 -10.11 -4.51 1426 BRIARS04-02 181 -10.06 -4.70 1446 BRIARS04-02 182 -9.95 -4.56 1466 BRIARS04-02 183 -9.77 -4.66 1486 BRIARS04-02 184 -9.69 -4.73 1506 BRIARS04-02 185 -9.57 -4.85 1526 BRIARS04-02 186 -9.45 -4.97 1546 BRIARS04-02 187 -9.56 -4.42 1566 BRIARS04-02 188 -9.44 -4.83 1586 BRIARS04-02 189 -9.36 -4.31 1606 BRIARS04-02 190 -9.37 -3.89 1626 BRIARS04-02 191 -9.99 -3.87 1646 BRIARS04-02 192 -10.41 -4.40 1666 BRIARS04-02 193 -10.88 -4.47 1686 BRIARS04-02 194 -10.61 -4.49 1706 BRIARS04-02 195 -10.81 -4.58 1726 BRIARS04-02 196 -10.73 -4.70 1746 BRIARS04-02 197 -10.03 -4.87 1766 BRIARS04-02 198 -9.65 -4.47 1786 BRIARS04-02 199 -10.08 -4.63 1806 BRIARS04-02 200 -10.56 -5.38 1826 BRIARS04-02 201 -9.98 -4.68 1838 BRIARS04-02 202 -10.32 -4.63 1849 BRIARS04-02 203 -10.09 -4.79 1860 BRIARS04-02 204 -9.56 -4.95 1871 BRIARS04-02 205 -10.04 -5.22 1882 BRIARS04-02 206 -10.52 -5.49 1893 BRIARS04-02 207 -10.55 -5.65 1904 BRIARS04-02 208 -10.25 -4.63 1915 BRIARS04-02 209 -9.92 -4.96 1926 BRIARS04-02 210 -10.13 -4.98 1938 BRIARS04-02 211 -9.91 -4.93 1949 BRIARS04-02 212 -9.69 -4.99 1960 BRIARS04-02 213 -10.18 -4.99 1971 BRIARS04-02 214 -9.75 -4.59 1982 BRIARS04-02 215 -9.53 -4.37 1993 BRIARS04-02 216 -9.40 -4.42 2004 BRIARS04-02 217 -10.18 -4.92 2015 BRIARS04-02 218 -10.48 -4.83 2026 BRIARS04-02 219 -10.04 -5.10 2037 BRIARS04-02 220 -9.44 -4.76 2049

PAGE 110

101 Appendix D: (Continued) BRIARS04-02 221 -9.27 -4.73 2060 BRIARS04-02 222 -9.65 -4.60 2071 BRIARS04-02 223 -9.75 -4.69 2082 BRIARS04-02 224 -9.84 -4.77 2093 BRIARS04-02 225 -9.16 -4.89 2104 BRIARS04-02 226 -8.67 -4.54 2115 BRIARS04-02 227 -8.88 -4.75 2126 BRIARS04-02 228 -9.35 -4.76 2137 BRIARS04-02 229 -9.78 -4.90 2148 BRIARS04-02 230 -9.98 -4.47 2160 BRIARS04-02 231 -9.61 -4.29 2171 BRIARS04-02 232 -9.36 -4.67 2182 BRIARS04-02 233 -8.89 -4.55 2193 BRIARS04-02 234 -9.07 -4.70 2204 BRIARS04-02 235 -9.95 -4.86 2215 BRIARS04-02 236 -10.15 -4.91 2264 BRIARS04-02 237 -9.47 -4.38 2310 BRIARS04-02 238 -9.75 -4.38 2356 BRIARS04-02 239 -9.87 -4.66 2401 BRIARS04-02 240 -9.78 -4.54 2447 BRIARS04-02 241 -10.01 -4.98 2493 BRIARS04-02 242 -9.79 -4.74 2539 BRIARS04-02 243 -9.54 -4.53 2584 BRIARS04-02 244 -9.27 -4.52 2630 BRIARS04-02 245 -9.52 -4.89 2676 BRIARS04-02 246 -9.62 -5.06 2721 BRIARS04-02 247 -9.25 -4.15 2767 BRIARS04-02 248 -9.46 -4.24 2813 BRIARS04-02 249 -10.04 -4.73 2858 BRIARS04-02 250 -10.04 -4.75 2904 BRIARS04-02 251 -10.28 -4.32 2950 BRIARS04-02 252 -9.87 -4.97 2996 BRIARS04-02 253 -9.53 -4.59 3041 BRIARS04-02 254 -9.36 -4.44 3087 BRIARS04-02 255 -9.20 -4.28 3133 BRIARS04-02 256 -9.91 -5.19 3178 BRIARS04-02 257 -9.13 -4.95 3224 BRIARS04-02 258 -9.45 -4.55 3270 BRIARS04-02 259 -9.14 -4.39 3315 BRIARS04-02 260 -9.54 -4.35 3361 BRIARS04-02 261 -10.15 -4.45 3407 BRIARS04-02 262 -10.11 -4.25 3453 BRIARS04-02 263 -9.20 -3.97 3498 BRIARS04-02 264 -9.32 -4.12 3544 BRIARS04-02 265 -9.21 -3.93 3590 BRIARS04-02 266 -9.34 -4.24 3635

PAGE 111

102 Appendix D: (Continued) BRIARS04-02 267 -8.87 -4.32 3681 BRIARS04-02 268 -9.39 -4.57 3727 BRIARS04-02 269 -8.67 -4.39 3772 BRIARS04-02 270 -9.42 -4.01 3818 BRIARS04-02 271 -8.56 -4.81 3864 BRIARS04-02 272 -8.30 -4.29 3910 BRIARS04-02 273 -8.47 -4.43 3955 BRIARS04-02 274 -8.18 -4.05 4001 BRIARS04-02 275 -8.65 -3.92 4047 BRIARS04-02 276 -8.29 -3.87 4092 BRIARS04-02 277 -7.58 -4.00 4138


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Soto, Limaris R.
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Reconstruction of late holocene precipitation for Central Florida as derived from isotopes in speleothems
h [electronic resource] /
by Limaris R. Soto.
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[Tampa, Fla.] :
b University of South Florida,
2005.
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Thesis (M.S.)--University of South Florida, 2005.
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Includes bibliographical references.
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Text (Electronic thesis) in PDF format.
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ABSTRACT: Little is known about the paleo-precipitation of the Florida Peninsula. In order to better understand Floridas late Holocene climate variability (last 4,200 years), the isotopic composition was analyzed of four speleothems from two caves, in West-Central Florida. Two speleothems were collected from BRC Cave in Hernando County, and two others from Briar Cave in Marion County. This study represents the first speleothem-based paleoclimate records for Florida. Uranium-series disequilibrium analyses were determined by using thermal ionization mass spectrometry (TIMS) to provide accurate determination of chronology of the deposition of the speleothems.Stable isotopic analyses of oxygen and carbon were performed using stable isotope mass spectrometry, which provided information regarding changing amounts of precipitation (increase in precipitation, decrease in the and#61540;18Oc) and types of vegetation above the cave (increased forest density, decrease in the and#61540;13Cc). Variations in the speleothems and#61540;18O composition reveal abrupt changes in precipitation amount, fluctuations that appear both regional and hemispheric in nature. Strong similarities between the speleothem and#61540;18O, Lake Tulaneand#61472;and#61540;D record (Cross et al. 2003; 2004) and the SE US tree-ring record (surrogate for spring precipitation Stahle and Cleaveland 1992) suggests a regional atmospheric influence on Floridas precipitation.The major causes of changes in precipitation are proposed to be Atlantic Multi-decadal Oscillation (AMO), El Nino and changes in the relative positions of the Intertropical Convergence Zone (ITCZ)-North Atlantic High (NAH). Comparison between the and#61540;18Oc and surrogates of these influences, show all three have some effect. AMO and El Nino have short-term (decadal) influence and ITCZ-NAH has a long term (centennial) influence. The contributions of these climatic effects have implications for teleconnections involving Floridas climate; the AMO correlation shows higher latitude influence, while El Nino and the ITCZ show tropical influence on subtropical Florida.
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Adviser: Philip van Beynen.
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Paleoclimate.
Stalagmites.
Stable isotopes.
Uranium-series.
Teleconnections.
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Dissertations, Academic
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