Carbon dioxide is the primary driver of dissolution and precipitation reactions in epigene limestone caves. While much work has been conducted on CO2 dynamics involved in dissolution in the phreatic zone, less research has been conducted on vadose CO2 dynamics, especially in tropical caves developed in eogenetic limestones. In this study, we investigate spatial and temporal variation in pCO2 in the deep vadose zone of eogenetic limestone above Jinapsan Cave, located in northern Guam. Five years of carbonate chemistry data from three dripwater sites in Jinapsan Cave (Flatman, Station1, and Trinity) were used to model the theoretical pCO2 with which infiltrating waters had likely equilibrated along flow paths between the soil and the cave. Theoretical pCO2 essentially models the amount of CO2 that would need to be added to dripwaters that have degassed and become supersaturated with respect to calcite upon entering a lower CO2 cave void in order to return the water to equilibrium. Theoretical pCO2 values range from 10-2.8 to 10-1.8 atm among the three sites examined. These results were generally lower compared to similar studies in telogenetic and continental karst, which range from 10-3.7 to 10-0.96 atm. Theoretical pCO2 data from Jinapsan Cave have significant differences among the three drip sites, with the site closest to the entrance (Flatman) having the highest values and the farthest from the entrance (Trinity) having the lowest values; in addition, the values also have a great seasonal variability. Low theoretical pCO2 values in Jinapsan Cave’s dripwaters indicate that vadose zones in eogenetic limestone may be better ventilated, and hence have lower pCO2, than those in telogenetic limestone. The ventilation of the vadose zone is facilitated by high matrix porosity and permeability of eogenetic limestone and may be driven by barometric pressure changes or wind.

A sequence of siliceous dolomite and magnesian limestone, known as Knox group rock are prevalent in karst landforms of Southern Appalachians. Thick blanket of clay-rich red soils (terra rossa) are common along fractures, cavities, and between bedding planes of these calcareous, cavernous rocks. The red soil causes serious environmental and geotechnical hazards, hence proper understanding of the soil's pedology, geochemistry and engineering behavior can lead to better site characterization for safer development. Twenty four terra rossa samples were collected and laboratory analysis was performed such as: geochemistry (mineral content using X-Ray diffraction, and geotechnical characterization (grain size distribution, porosity, hydraulic conductivity, and shrink-swell potential). The soil profile above Knox rock exhibits distinct vertical variation in geochemical and geotechnical characteristics. The soils are well drained in the upper horizon and exhibit slight reduction in porosity and hydraulic conductivity with depth. The analysis indicate that these soils overall are good foundation materials, however proper drainage should be installed to prevent foundation damage, soil erosion and landslides in slopes.

The Late Neogene represents warm Earth conditions immediately prior to the development of extensive northern hemisphere glaciation, and this period in Earth history may therefore provide the best available analog for the projected outcome of continued global warming. There are few interior continental sites of Late Neogene age from the eastern half of North America and subsequently very little is known about the conditions characterizing climate. The Early Pliocene (~ 5 Ma) Pipe Creek Sinkhole (PCS) includes the sediment fill of a complex karst environment that developed in north-central Indiana, USA (Lat. 40° 27′ 25.4″, Long. 85° 47′ 37.2″). The site includes more than 3 m of high-chroma, red-colored silty-clay sediment interpreted to be terra rossa. The terra rossa δ13C values average - 20 ± 0.7‰ PDB and are interpreted to represent sediment deposited in a closed cave system under high summer temperatures and with well-drained soils. An in-situ paleosol at the top of the terra rossa represents a transition from a closed cave to an open environment that eventually flooded, thereby becoming a small pond. δ13C values from lacustrine sediments with organic matter derived dominantly from algae average - 20.6‰ and suggest the pond was stagnant and enriched with bicarbonate from the underlying limestones or via aquifers. Pond sediments include abundant vertebrate fossils, which are broadly consistent with those inhabiting an open ecosystem such as a savannah or parkland. However, the PCS pollen includes low taxonomic diversity that is dominated by pine with some hickory and flowering plants, but no grass pollen. We propose two hypotheses to explain the PCS stratigraphic record: (1) The pollen assemblage may represent a local pine dominated ecosystem associated with the pond paleoenvironment, such as a riparian community, and that the greater landscape was drier and open; (2) Alternatively, the climate may have became wetter raising the elevation of the groundwater table and initiating the formation of the pond. Then in response to the wetter conditions an early succession forest ecosystem developed.

Groundwater is documented to flow through solution-widened fractures and bedding planes in limestone and dolostone units in low-relief topography. This enhancement, or karstification, is much harder to study in alpine environments like the Bear River Range of northern Utah. This is problematic, due to the fact that the Bear River Range karst aquifer system supplies the City of Logan with a large quantity of water at Dewitt Spring. Furthermore, the karst aquifer sustains the Logan River for much of the year, and may allow groundwater to flow directly in the subsurface to the Cache Valley principal aquifer system. Flow measurements along the Logan River constrain a minimum volume of 2.32x106 m3 /y (1.88x103 af/y) that could recharge the Cache Valley principal aquifer. Hydraulic characteristics of alpine karst were estimated by analysis of major ions, stable isotopes, and dissolved gases in spring waters. These data reflect quick groundwater flow through caverns, with no evidence for “diffuse” flow anticipated by some to occupy interstitial space. In fact, the oldest reasonable estimated recharge age for groundwater is 70 years. Young recharge, fast flow, and low storage capability indicate that alpine karst aquifers are very sensitive to droughts and that related water resources are vulnerable to longer-term changes in climate.

No description available.

No description available.

Sea-level change during the Quaternary has had significant impacts on the geology of the Bahamas and the global carbon budget. During periods of low sea-level position conduit caves form in the Bahamas as a function of their respective water budgets. These conduit caves can then collapse and if this collapse reaches the surface a progradational collapse blue hole can be made. Upon subsequent sea-level rise these blue holes can become sediment inilled. Tidal pumping through these sedimentilled blue holes can result in the formation of whitings. Whitings are formed when the tidally pushed water warms and degasses CO2, driving the precipitation of CaCO3. Whitings are also formed on the shallow banks by resuspension by fish. As sea-level fluctuates the amount of land in the Bahamas and other carbonate regions increases or decreases with sea-level fall or rise, respectively. As the amount of land increases in the Bahamas and other carbonate regions, there is a decrease of carbonate rock exposure at high latitudes due to glaciation. The loss of high latitude carbonates is made up for in the gain of low latitude carbonates in terms of rates of inorganic carbon drawdown associated with karst processes. Additionally, this inorganic carbon draw down from karst processes represents approximately 16% of the unknown carbon sink as reported by the IPCC. This study is significant in that it contributes to the understanding of sea-level fluctuations in relation to the geology of the Bahamas and the global carbon budget.

Dissolutional voids in the subsurface were examined from three different viewpoints. First, analysis of pseudokarst features on San Salvador Island, Bahamas, uncovered the involvement of organics in the cementation and porosity generation process. This organic material was analyzed using SEM, TEM, and in thin section. While the actual role of organics in the cementation process could not be determined using these tools, the abundance of the material was documented. Holocene samples appear to have more organics than Pleistocene samples. The abundance of this material should have an effect on isotope analyses and needs to be considered in future work on meteoric cements and the environments where they form. Second, work on Mallorca Island, Spain, demonstrated how the placement and abundance of exposed caves could predict subsurface cave distributions. This work measured caves along exposed coastlines and in protected areas known as calas. Results found that caves within the calas have larger volumes and aerial footprints than caves on the exposed cliffs. The cave distributions showed that calas had to form prior to cave formation. Several paleo-slump features were observed and are believed to be the result of collapsed Tortonian flank margin caves, which were later inilled with Messinian sediments, using the caves as limited accommodation space, resulting in these sediment layers unaffected by the collapse further up section. Third, the current method of cave data manipulation to produce cave areal footprints and volume was found to be incorrect and in need of a calibration mechanism. This calibration was determined by reviewing how Compass cave mapping software generates volume estimates, using shapes of known volumes. Cave surveying techniques were also reviewed to determine if survey protocol affected volume outputs. Surveying in straight lines, down the center of a passage, avoiding splay shots, and taking left, right, up and down measurements (LRUDs) were found to generate the most accurate volumes estimates using Compass. These protocols were used to remap caves from paper maps to generate correction factors. Propriety software was used that could “shrink wrap” a 3D cave map rendering to produced values for cave volume and porosity and rock porosity.

Groundwater flow through fractured karst conduit systems can be complex and difficult to diagnose. This project explores the role of geologic structures that influence the location of recharge points, flow paths, velocities, and discharge locations within Morrell Cave and at the resurgence of Morrell Spring, both of which are located near the city of Bluff City, TN. Understanding of the groundwater sources and flow paths in the Bluff City area will allow future researchers to more readily identify sources of pollution and better resolve local agricultural well drawdown conflicts among residents. The objectives of this project are to: 1) identify the active allogenic recharge sources of Morrell Spring, the largest known spring in the Bluff City area; 2) delineate a springshed for Morrell Spring and; 3) diagnose the structural controls for groundwater flow paths to Morrell Spring. It was found that surface streams flowing across the Sevier Shale on the northern slope of Holston Mountain enter the subsurface karst system through swallets along the Sevier shale and the Jonesboro Limestone contact. Once underground the water flows to the NW following 2 dominant joint sets until it reaches the NE/SW oriented fault line along which Morrell Cave has formed. Upon entering the cave the groundwater flows to the NE to Morrell Spring and into the South Fork Holston River.

Groundwater tracing studies have shown a well-developed conduit system in the karst aquifer beneath the Buffalo Creek Watershed of Carter County, TN. Groundwater can quickly travel beneath topographic divides, transporting contaminants. Using GIS and field reconnaissance, two sites were selected for a two phase dye trace study. In May-June 2016 groundwater resurgences were located using activated carbon samplers, and in October-December 2016 flow velocities were measured using ISCO automatic water samplers. In study 1, a stream sinking in the back of Carter Saltpeter Cave was traced to its resurgence at Cave Springs Cave. In study 2, the dye mass centroid passed the resurgence 23.2 hours after injection. During study 1, dye injected into a sinkhole near the headwaters of Toll Branch rapidly diffused into multiple conduits. In study 2, dye from the Toll Branch site was not recovered, indicating that groundwater follows different flow paths dependent on water table level.