Evolution of rocky coastlines is controlled by littoral, biological and fluvial processes. Resultant landforms are overprinted and/or new ones formed as a result of changes in sea level caused by glacioeustasy and/or local tectonics. On carbonate coasts, chemical erosion in the form of karstification takes on a dominant role. Type of karstification is an important factor in understanding carbonate coast evolution and landform development so it is critical to identify type of karstification. In this research, fractal indices were used to distinguish cave and thus karstification type. It was determined that fractal indices effectively differentiated cave types and the indices were used to distinguish cave types at study sites on Barbados, the ABC Islands (Aruba, Bonaire, Curaçao) and the Caribbean coast of the northeast Yucatan peninsula, Mexico. This research evaluated caves located in the phreatic, epiphreatic and vadose zones of the northeast coast of Quintana Roo, Mexico to determine the relationship between the caves and to coastal processes. Three distinct coastal landforms associated with caves on 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 and fluvial-karstic 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 morphology of the bokas was a function of dominant geomorphic process. The caletas of the Yucatan Caribbean were formed by karstification processes that also produced features with mixing-zone-like morphologies but with fluvio-karstic function. The results of this research expand the Carbonate Island Karst Model (CIKM), which explains eogenetic dissolutional processes and landforms on small carbonate islands, to one that includes carbonate islands of all sizes, and carbonate continental coasts.

Coastal karst aquifers are important water resources, often providing the only source of freshwater to coastal communities for agriculture, industrial usage and human consumption. In order to implement management strategies and preventative measures for future perseveration of this resource, it is imperative to understand how coastal groundwater conditions are controlled by the interaction of freshwater/seawater on local and regional scales, but also over recent and past time periods. However, there is a limited resource of published hydrological data on recent aquifer conditions. In the Yucatán Peninsula and other anchialine environments, this lack of information inhibits the understanding of the spatial and temporal interaction of the meteoric and marine water masses. Documenting how the aquifer is responding to forcing mechanisms such as large precipitation events, seasonal cycles and short-term sea level rise (e.g. storm surge) will assist in understanding modern aquifer condition but also the interpretation of paleo-records. Utilization of water level and salinity sensors in strategic positions in the aquifer demonstrate that meteoric water mass salinity varies over wet and dry seasons with the movement of the halocline, but also on a short-term basis though large rainfall events. Salinity in the meteoric water mass is influenced by mixing with the marine water mass during intense precipitation events associated with Hurricane Ingrid (2013), Tropical Storm Hanna (2014) and a series of unnamed events in 2015. During wet periods, induced flow from increase precipitation causes turbulent mixing with the marine water mass, increasing salinity in the upper meteoric lens. On the contrary, during dry periods, mixing is reduced, therefore making the meteoric lens less saline. This contemporary understanding of meteoric/marine water mass dynamics can be applied to developing and calibrating the geochemical record of calcite rafts, calcite precipitation at the air-water interface of cave pools, as a hydrological proxy for aquifer conditions. Our monitoring of calcite raft formation, deposition and geochemistry shows that raft accumulations (e.g., raft piles/cones) can offer a good paleoenvironmental archive of changing hydrological conditions. Based on a 2-year observational record, results indicate that calcite raft precipitation/formation occurs continuously but with only minor biases with intense rainfall events altering supersaturation conditions in the surface waters. Testing the use of calcite rafts in sediment cores from Hoyo Negro show that geochemical analyses (87Sr/86Sr, δ18O, δ13C, Sr/Ca and Cl/Ca) show that meteoric water mass salinity varied during the Holocene (~ 8.5 Ka – present) likely due to changing rainfall and or cave passage geomorphology, which is coherent with other independent climate records. Prior to this study, calcite rafts have never been considered a paleo-hydrological archive for aquifer conditions, however, the consistency and cross-validation with independent records demonstrates great potential for future paleohydrological reconstructions. / Thesis / Doctor of Philosophy (PhD)

The disintegration of the Classic Maya throughout the Terminal Classic (750-900 C.E.) is a complex loss of human population that has presented many questions about climate change and its impact on humanity. With droughts proposed as a prominent cause, understanding the quality and availability of groundwater resources at the time is pivotal to further determining the spatial and temporal distributions of population deterioration. The Yucatan aquifer consists of karstic cave systems, with a small number of inland lakes, which have previously been termed closed to the aquifer. It is important to understand how both of these types of water bodies react to long- and short-term forcing mechanisms such drying climate, sea-level rise and precipitation events. Using a variety of spatial and temporal records to determine aquifer evolution, changes and connectivity throughout the Holocene it will further understanding of how the aquifer reacts to changes in climate and the implications this may have had on the Classic Maya. Four sediment cores from Pac Chen Lake and two sediment cores from Carwash Cenote were collected to investigate Holocene paleoclimatic trends on the Yucatan Peninsula in Mexico. Records of past climate, groundwater conditions and flooding history at both sites were determined through microfossil and micro X-Ray fluorescence data. In Pac Chen Lake, elevation and timing of flooding of the lake coincided with sea-level rise. Using Ti, Fe and K records to determine wet vs dry conditions, dry periods through the terminal classic coincided with other paleoclimate records, but with no evidence of draw-down within the lake. Both of these observations imply connection of the lake to the aquifer. The Cl record from Carwash was used alongside a core from the Yax Chen cave system to observe spatial and temporal potability of the aquifer. An overall freshening trend in the coastal groundwater occurred throughout the Holocene. The largest amount of this freshening transpired through the Terminal Classic. At this time, populations inland were experiencing deterioration, while coastal populations along the coast continued to survive. Comparing Cl records at various depths and distances from the coast proved that Cl is impacted by proximity to the halocline. / Thesis / Master of Science (MSc)

La côte ouest irlandaise située dans les comtés de Clare et Galway est depuis récemment affectée par une augmentation de la fréquence des inondations et une montée du niveau marin. L'impact de ces changements climatiques se fait particulièrement ressentir au niveau des aquifères karstiques côtiers de ces régions, tel que le bassin karstique de Bell Harbour (~50 km²) sélectionné dans le cadre de ce projet: le positionnement d'un biseau salé dans cet aquifère est clairement dû à l'interaction entre sa recharge liée aux événements pluvieux et la forte influence de la marée. Des données (niveaux d'eau et conductivités spécifiques) ont été collectées à l'aide de sondes, à deux sources côtières, six forages, trois lacs et au milieu de la baie durant des périodes prolongées. Trois types d'environnement hydrodynamiques (conduits, fissures et matrices) ont été définis pour chacun des six forages en comparant deux méthodes qui se sont avérées cohérentes entre-elles. Les variations des conductivités spécifiques combinées à la chimie des eaux des six forages et de lacs ont permis d'évaluer l'étendue du biseau salé dans l'aquifère en fonction de la recharge de l'aquifère et des cycles de marée haute/basse et vives eaux/basses eaux: l'étendue du biseau salé dépend des propriétés hydrodynamiques de l'aquifère mais aussi de l'influence relative de la recharge et de la marée sur les niveaux piézométriques, induisant chacun des comportements opposés. Ainsi, la compétition entre la recharge et la marée contrôle l'intrusion d'eau de mer dans l'aquifère, ce qui explique les changements spatio-temporels du biseau salé dans l'aquifère. Les fortes amplitudes de marée semblent être le moteur des brèves intrusions salines dans l'aquifère proche de la rive alors que la position du niveau piézométrique semble influencer l'intensité de cette augmentation de la salinité. La recharge karstique de la région est suffisamment importante tout au long de l'année pour que le biseau salé ne s'étende pas plus loin qu'un kilomètre de la rive. La diminution des précipitations durant l'été (~10 %) ainsi que l'augmentation du niveau marin prévues pour les prochaines décennies, contribueront certainement à une intrusion plus importante du biseau salé dans l'aquifère. / Low-lying coastal areas in the west of Ireland, such as the Galway and Clare coasts, have seen recent increases in flooding frequencies coupled with overall increases in sea level. The impacts of these changes are most strongly felt in coastal karst catchments and this study focuses on one such area, the Bell Harbour catchment (~50 km²), where there is a clear interaction between rainfall inputs and tidal influences, to create a terrestrial salt water wedge. Data (specific conductivity and water levels) have been collected at two coastal springs, six boreholes, three lakes, and from discrete locations in the middle of the bay, using dedicated loggers over extended periods. Two approaches that provided consistent results were used to explain the different hydrodynamic behaviours identified in the boreholes (conduits, fissures and matrix flows). Specific conductivity variations and water chemistry measured inland allowed for assessment of the spatial extent of the saltwater wedge into the aquifer as a function of both karst recharge and tidal movements at high/low and neap/spring tidal cycles. The extent of the saltwater wedge depends on the intrinsic properties of the aquifer but also on the relative influence of the recharge and the tide on groundwater levels, which induce opposite behaviours. This dynamic between recharge and the tide thus controls the seawater inputs, hence explaining temporal and spatial changes in the saltwater wedge in this coastal karst aquifer. Strong tidal amplitudes seems to be the motor of sudden saltwater intrusion observed in the aquifer near the shore while the relative elevation of the groundwater appears to influence the intensity of the salinity increase. The magnitude of annual recharge in the area is high enough to limit saltwater intrusion to no more than about one kilometre inland from the shore. Given the anticipated decreases in summer precipitation (~10 percent), coupled with anticipated sea level rises, the extent of the saltwater wedge into the aquifer is likely to increase in coming decades.

La marge provençale, localisée au Nord-Ouest de la Méditerranée, constitue avec la marge du Golfe du Lion et la marge ligure, la bordure septentrionale du bassin Liguro-Provençal. L'objectif principal de ce travail est la reconstitution de l'histoire géodynamique, structurale et géomorphologique de la marge depuis le Tertiaire. Sa structure est principalement le résultat des phases tectoniques anté-miocènes. Sur la marge provençale la transition entre le plateau continental et le bassin est étroite et caractérisée par des pentes abruptes affectées par des phénomènes d'instabilité gravitaire dans l'axe du canyon sous-marin de Cassidaigne. A terre, la marge provençale est caractérisée par une compression pyrénéenne, des fossés oligocènes, et une sédimentation mésozoïque à cénozoïque essentiellement carbonatée propice à l'infiltration des eaux en profondeur. L'origine des cours d'eau de la région est essentiellement karstique, et les sources côtières de Port-Miou et Bestouan constituent des réseaux karstiques noyés développés sur plusieurs kilomètres dans le calcaire urgonien, au droit du canyon de Cassidaigne. Les travaux antérieurs suggèrent que l'absence de réseau fluviatile de surface en amont et la forme de reculée karstique de la tête du canyon de Cassidaigne sont le résultat d'une connexion karstique entre les sources côtières et le canyon, que la marge provençale n'ait pas été affectée par l'érosion messinienne et la transgression pliocène, que certains dépôts transgressifs marins miocènes sont situés à des altitudes anormalement élevées par rapport à leurs niveaux de dépôt théorique. / The Provence Margin is situated in the north-western Mediterranean and constitutes the northern edge of the Liguro-Provençal Basin with the margins of the Gulf of Lion and Ligurian sea. The main objectif of this thesis is the reconstruction of the geodynamic, structural and geomorphologic history of the margin since the Tertiary. This margin is mainly structured by ante-miocene tectonic events. On the Provence Margin, transition between the continental plate and the basin is narrow and characterized by abrupt slopes and associated gravitary instability within the axis of the Cassidaigne canyon. The Provence Margin is characterized by Pyrenean compression and Oligocene extension. The Mesozoïc-Cenozoïc sedimentary pile is dominated by carbonate rocks favorable to water circulation. The origin of the river system in the region is essentially karstic, and the coastal springs of Port-Miou and Bestouan correspond to drowned karstic network that develop along tens of kilometers within the Urgonian limestone, updip of the Cassidaigne Canyon. Previous work suggest (1) that the lack of updip river system and the karst pocket valley shape of the canyon head are the result of an active karstic connexion between the coastal springs and the canyon, (2) that the Provence Margin is not affected by the Messinian erosion and Pliocene transgression, and (3) that Miocene marine transgressions are preserved at higher altitudes than their theoretical level. These facts witness a recent tectonic deformation that is not well understood. This work is based on the integration of geology, geomorphology and hydrogeology with the aim to understand evolution and functioning of coastal karsts