INFLUENCE OF KARSTIC, FLUVIAL, AND LITTORAL PROCESSES ON THE DEVELOPMENT OF LANDFORMS ON ROCKY CARBONATE COASTS

The evolution of carbonate coastlines is controlled by littoral, chemical, biological and fluvial processes. Resultant landforms are overprinted and new ones form due to changes in sea level. Karst processes of hypogene and/or epigene types take on a dominant role in coastal karst evolution and in the development of coastal landforms. In the Caribbean region glacio-eustasy and to some degree, tectonics during the past 200,000 years have caused significant fluctuations in sea level. High stands resulted in coral reef development on island and continental coasts, and low stands subaerially exposed carbonate coasts allowing emplacement of freshwater lenses and the initiation of karstification. In this study morphometric analysis of land forms and fractal indices of caves within the phreatic, epiphreatic and vadose karstic zones were used as proxies for determining karst type at study sites on Barbados, the ABC Islands (Aruba, Bonaire, Curaçao) and the Caribbean coast of the northeast Yucatan peninsula, Mexico. Three distinct coastal landforms associated with caves in the study sites were evaluated to quantify and model the interplay of littoral, fluvial and karstic processes and cave and karst development. On Barbados, the combination of surface fluvial processes, and mixing-zone dissolution, resulted in the formation of gullies. Some gullies contained caves in their bounding walls and/or served as points of recharge to fluvial caves. Bokas of the ABC islands are distinctive geomorphic structures that formed from the interplay of fluvial, littoral and mixing zone karstification. The caletas of the Yucatan Caribbean were formed by karstification processes that produced features with mixing-zone-like morphologies but with fluvio-karstic function. The development of these features reflect a range of geomorphic agents that include a combination of fluvial, littoral, and karstic processes that operate during periods of stable and fluctuating sea level.