Tafoni have been confusingly defined in many ways: variations in size, rock type, and forming mechanisms. This study addresses tafoni in Quaternary eolian carbonates to help better define the term. Large tafoni were differentiated from other coastal caves in the Bahamas, specifically flank margin and sea caves, using morphometric analyses. The differentiation is important as all three cave types form in the same area, but flank margin and sea caves can be used as paleo-sea level indicators, while tafoni cannot. Small tafoni show a growth rate of 0.022 m3/yr; and may amalgmate to form larger tafoni, which grew at 0.65 m3/yr. Petrographic analysis helped identify tafoniorming mechanisms; results revealed no evaporites present, removing crystal wedging as a mechanism, while indicating wind erosion as the primary mechanism. This analysis found significantly greater cements within the Holocene rocks compared to previous studies, and SEM analysis revealed organic cements preserved by oil-based cutting.

Banana holes are a common karst feature of The Bahamas and several theories have been presented to explain their origin. The current model for banana hole formation places their dissolution at the mixing zone at the top of the fresh water lens. This theory is based on the observation that banana holes are often found in the interior of islands, far from the dissolutionally aggressive fresh water lens margin. This study proposes that banana holes form at the lens margin as it follows a prograding strandplain. Spatial observations show that banana holes appear to be associated with low inland ridges and their orientation appears to correlate with features found on modern shorelines. Bedding features such as herringbone cross beds and back-beach rubble found in banana hole wall rock point to a progradational environment of deposition for banana hole host rock.

A geodatabase and a data management program have been created to store and manipulate cave and karst feature data from the Bahamas. A geographic information system was used to recognize any spatial patterns in the cave and karst data from San Salvador Island. Elevation data for banana holes, vadose pits and flank margin caves were obtained from a digital elevation model and are consistent with values predicted by the Carbonate Island Karst Model. The slope and aspect of the hill on which a flank margin cave is found showed no relationship to cave sizes and shapes, emphasizing the hypogenic nature of flank margin caves. The digital elevation model further demonstrated the position of lakes on San Salvador Island during the last interglacial (OIS 5e) highstand, and the lack of flank margin caves along the shores of these lakes provides evidence for a paleoclimate on San Salvador Island similar to today?s.

Abaco Island is located on Little Bahama Bank at the northwestern extent of the Bahamian Archipelago. Karst features on Abaco include: flank margin caves, karren, blue holes, pit caves, banana holes, and cone karst. As part of this study all known flank margin caves on Abaco were GPS located and surveyed. The presence and locations of the other karst features were recorded as part of the karst inventory of Abaco. The cone karst is of particular interest because cone karst has not been documented on other Bahamian islands. These cones form from the dissection of an eolianite ridge due to karst, fire, and vegetative processes. Tafoni-like recesses, originally believed to be high flank margin caves, were formed during cliffing of an eolianite ridge during the OIS 5e highstand. The geologic evolution of representative depositional sequences on Abaco fits within the accepted Bahamian stratigraphy.

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.

Geomorphic features have been one of the major tools for sea-level change studies. The present work shows an example of sea-level change study on karst terrain in the tropics. Sea-level notches as well as flank margin caves were identified in the research area and their elevation measured. The time of formation of the sea-level indicators was constrained by lithology study and dating methods such as facies comparison and U-Th dating. Denudation and uplift were also studied for the same purpose. From this study it can be concluded that sea-level stands within the glacial cycle can cause the formation of flank margin caves and that the position of these sea-level stands can be determined. The research area was estimated to have cumulatively uplifted ~22 m in the past 125 ka years (~0.18 mm/yr) while the surface has been denuded some 8 m in the same span of time (~0.064 mm/yr).