Three questions were asked during this research. 1) Does the Sr content of Caribbean speleothems have a direct relationship with the age of the host rock at the time of speleothem precipitation?; 2) do older speleothems contain less Sr than younger speleothems in the same climatic setting?; and 3) will speleothems record the change in Sr concentration of eogenetic carbonates as a faster depletion in climates of higher precipitation as opposed to drier climates? The speleothems and cave rocks in this study were analyzed with various methods in an attempt to understand the rock processes that affect speleothem Sr concentrations. Evidence to support the hypothesis that younger host rock contributes higher concentrations of Sr to speleothems was found in the stalagmites of Curacao while Bahamian stalagmites indicated climatic variations. The results have implications for using stalagmites from relatively young, eogenetic limestone as a proxy for Sr-related paleoclimate data.

Caves, the cornerstone feature of karst aquifers, are little understood in Florida. This dissertation, which analyzes the morphology, elevation, lithologic setting, and hydrology of caves in west-central Florida, demonstrates that the karst of the unconfined Floridan aquifer differs from the paradigm view of karst presented in modern geology textbooks. The differences reflect setting: eogenetic (west-central Florida) vs. telogenetic (conventional). Interpretations about the architecture of cavernous porosity in this dissertation come from detailed surveys (497 stations) of seven air-filled caves.The surveys reveal that solution cavities within the unconfined Floridan aquifer align along NE-SW and NW-SE fractures. The surveys further identify tabular zones of cavernous porosity that extend for tens of meters. Characteristic "plus-sign" passages occur at the intersection of solution-enlarged fractures and the tabular horizons. The caves, as surveyed, do not connect points of discrete aquifer input to springs. Rather, they are separated by intact bocks of aquifer matrix, ever- narrowing fissures, sediment fills, and breakdown. With an additional 574 spot elevations from 63 previously surveyed air-filled and submerged caves and 526 foot-length cavities encountered in 26 drilled wells, the assembled data reveal that cave passages above and below the watertable of the unconfined Floridan aquifer cluster at similar elevations throughout west-central Florida. At the largest scale, the levels of cavities cut across geologic structure, thus suggesting a water-table origin. The close linkage of the water table and sea level this coastal setting suggests the levels reflect positions of paleosea level. Given that the air-filled caves in west-central Florida reflect higher sea levels,the coastline would have been close when the air-filled caves formed. The levels organize according to a sea-level datum at elevations of 30 m, 20-22 m, 12-15 m,and 3-5 m. The levels are similar in elevation to nearby terraces evident in GIS and LIDAR topographic data. The terraces correspond to the classic, Quaternary marine terraces of the coastal plain of the southeastern U.S.A. Given that the now-submerged caves reflect lower sea levels, the coastline was far from the caves when they formed. They organize according to a watertable datum at depths of 15 m, 30-40 m, 60-70 m, and > 100 m with some correspondence to marine terrace and paleoshoreline features identified on the sea floor of the west florida shelf using GIS and multibeam bathymetry. The multigenerational origin of these deeper caves masks the correspondence. Although past water tables are seen to be the first-order control of cave passages regionally, lithology appears to play a significant role at the scale of an individual cave. Approximately 2,000 measurements of matrix permeability from more than 228 m of continuous core from the unconfined Floridan aquifer of west-central Florida reveal a wide-ranging facies-dependent matrix permeability[log k(m2)= -12.9 +/- 1.6, total range]. Solution passages tend to be wider where the matrix permeability is greater. Time-series analysis on measurements of spring discharge from 31 springs and published time series from 28 additional sites reveal key differences between eogenetic and telogenetic karst aquifers, reflecting the difference in matrix permeability of the eogenetic [log k(m2) from -14 to -11] and telogenetic[log k(m2) from -15 to -20] limestones. For instance, log Q/Qmin flow-duration curves have greater slopes at eogenetic karst springs, a manifestation of lowerratios between the maximum and mean discharge (Qmax/Qmean). Additionally,aquifer inertia as defined on auto correlograms is greater in eogenetic karst than telogenetic karst.Hydrographs of spring flow and water level vary on a seasonal or longertime scale. The localized, convective-style storm events typical of the Florida summer rainy season are not realized as individual peaks in these hydrographs.Apparently, large, widespread, storm events, such as hurricanes in the late summer and fall and frontal systems in the winter and spring, are necessary to produce significant changes in storage. Data from nine pressure transducers in caves and in the aquifer matrix across the unconfined Floridan aquifer all record immediate increases in the water level due to Hurricanes Frances and Jeanne in September of 2004. The increases are simultaneous over large regions. These changes do not propagate through the aquifer as a pulse like the classic scenario of conduit flow in telogenetic karst aquifers.

Rota Island, the southernmost island in the Commonwealth of the Northern Mariana Islands in the western Pacific, has the types of caves previously documented on the other limestone mantled islands in the Mariana Arc that have been investigated for caves: Aguijan, Guam, Tinian and Saipan. Caves developed at the edge of the fresh-water lens by zones of enhanced carbonate dissolution produced by fresh-water/salt-water mixing are most common. Among these mixing zone caves, flank margin caves dominate. Flank margin caves were found singly and in extensive horizons representing significant sea-level still stands. However, another type of mixing zone cave was found on Rota in numbers not documented on neighboring islands. Mixing zone fracture caves, apparently formed as zones of enhanced dissolution, produced fresh-water discharging from the lens along fractures, migrated vertically as sea-level changed. Some mixing zone fracture caves on Rota are developed in clusters from two to four caves. The mixing zone caves of Rota reflect the interaction of eogenetic limestone, glacioeustasy, local tectonics and enhanced carbonate dissolution via mixing of disparate waters. The development of mixing zone caves on Rota is in agreement with the Carbonate Island Karst Model (CIKM). Rota has a few caves developed along the contact between limestone and the insoluble volcanic rock that makes up the core of the island. The most important of these is Water Cave, a large spring that is the source for most of the municipal water on Rota. Rota also two extensive zones of vertical fissures developed along bedrock fractures; Fissure City and As Mundo Fissure Zone. In addition, Rota has one cave apparently developed along a fault; Gagani Cave. Some of the caves documented on Rota are difficult to classify and warrant further investigation.

Flank margin caves of the Bahamas are formed by mixing dissolution in a fresh-water lens. As they evolve, the probability of intersecting neighboring voids increases, and they enlarge in a nonlinear fashion. Large flank margin caves become constrained by surface topography and their morphology is influenced by the shape of the enclosing land mass as a result. High phreatic ceilings can be dissolved if the fresh-water lens is distorted by lithological heterogeneities or hydrologic loading due to storm events. Early diagenesis of the host rock causes the reorganization of porosity and permeability through dissolution and cementation processes. Meteoric overprinting occurs but cannot be used as a tool in determining the age of eolianites or the climatic conditions at the time of deposition. Current evidence indicates an OIS 5e speleogenesis of large flank margin caves. An OIS 11 origin can be advanced only with compelling evidence of a pre-OIS 5e highstand.