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As closed topographic depressions, sinkholes effectively divide karst regions into a series of subwatersheds, where swallets within each sinkhole define the downstream end of each subwatershed. Water and sediment are temporarily stored in sinkholes before continuing to underground streams. While pathways and travel times of water in karst terrain are commonly found using tracing techniques, such techniques do not provide information about the movement and travel time of sediment through these systems. This paper reviews the literature regarding sediment storage within sinkholes and presents a case study, the objective of which is to estimate the magnitude and timing of sediment deposition within three sinkholes in an urbanized area in Tennessee, United States of America. Sedimentation rates in sinkholes were estimated based on age determination of cultural artifacts (buried trash and coal fragments) and by 14C dating. For the three study sinkholes, minimum deposition rates (maximum residence times) were 15 cm yr -1(6 yrs), 1.5 cm yr -1(81 yrs), and 0.2 cm yr -1(640 yrs). The analysis revealed that sinkholes undergo fill and flush cycles at different timescales caused by changes in upland sediment supply and morphologic changes at swallet openings. Sinkholes that lack swallet openings, or with swallets that have become blocked by debris, are effectively disconnected from master streams with regard to sediment. Sediment stored in sinkholes may be released downstream when swallet conditions change. [ABSTRACT FROM AUTHOR]

The valleys within the Appalachian Mountains are often floored by carbonates. When remediating or preventing sinkhole activity in any karst, consideration should be given to a number of geologic, geotechnical and environmental concerns. Primarily, one must recognize that Appalachian karst is most likely variably faulted and folded and cannot be evaluated in the same manner as the flat-lying carbonates of the mid-continental US or the lightly cemented, recent karst of Florida. Also, in the tectonically abused rocks of the northeastern US, with their resultant solutioned discontinuities, one must also recognize the possible effects that glaciation may have had in the more northerly portions of the region. Investigative tools that can aid in deciphering these considerations include aerial imagery, review of sinkhole maps, geologic reconnaissance, test pits, test borings and percussion probes. In the authors' experience geophysics, unless combined with hard data, rarely provides useful geotechnical information even when costly programs are performed by competent individuals. Depending upon the nature of the sinkhole/doline and its effects upon man-made and natural environments, a number of effective remedial measures are available. This paper briefly addresses these various types of remediation including high and low mobility grouting, drainage maintenance, dynamic compaction (destruction) and structural solutions in relation to the encountered conditions, with consideration for economics, and will present case histories illustrating a number of problems and solutions in discussion. [ABSTRACT FROM AUTHOR]

Eight recharge areas have been delineated in the sinkhole plain of Perry County, MO, USA. The groundwater systems delineated were the Moore Cave system, Keyhole Spring, Ball Mill Spring, the Crevice Cave system, the Mystery Cave system, the Rimstone River Cave system, Thunderhole Resurgence, and Running Bull Cave. These systems include four of the five longest caves known in Missouri and two of the top four in having the most globally rare species. The delineations were done in support of the grotto sculpin ( Cottus specus) which is a fish adapting to cave environments, and because these cave streams seem to be the source of impairment in their receiving streams. Seventeen springs, including overflow springs, are associated with these groundwater systems. The results of a total of 87 dye introductions were used to complete the delineations, and the sampling network included 93 sampling stations. The tracing showed that the Mystery Cave system overflows to several springs under high flow conditions. Almost 94 km of land were included in the delineations. Hazards and vulnerability were also mapped. All of the recharge areas have potentially ineffective private septic systems, agriculture without universal application of best management practices, roads with poor water quality runoff and the threat of spills, and sinkhole dumps. The Crevice Cave system recharge area also has the City of Perryville, numerous underground storage tanks, and several facilities with national pollutant discharge elimination system (NPDES) permits, and hazardous waste generators, making it the least likely system to be a practical target for conservation. All of the recharge areas were mapped as highly vulnerable due to the rapid recharge of groundwater through discrete karst features. The data generated from this investigation can be used to direct efforts to conserve the grotto sculpin and improve water quality in the cave streams and in their receiving streams. [ABSTRACT FROM AUTHOR]

Situated in southwestern Illinois, principally within Monroe, St. Clair, and Randolph Counties, the sinkhole plain contains the highest density of karst features within the state, and cover-collapse sinkholes are distinctive rural landscape features. However, after decades of using large-scale farming equipment, modification by farm operators using drainage stand pipes and fill material, coupled with the widespread adoption of conservation tillage methods beginning in the 1980s, numerous sinkholes are now partially or completely indistinguishable on current maps and aerial photography. The result is that the land surface in this region has developed a relict, or palimpsest karst appearance. To detect and catalog now relict karst features, county-wide historical aerial photography was digitized and orthorectified to create a geometrically accurate image base map of the entire region. Acquired during the summer of 1940 by the U.S. Department of Agriculture, Agricultural Adjustment Administration (AAA), the AAA aerial photography represents the earliest and most detailed visual record of the landscape prior to the general introduction of mechanized farming practices. Because horse-drawn farming equipment was still prevalent in the region, pesticide and fertilizer application mostly unknown, row crops were planted at much lower plant densities. Therefore, the near-surface geology was able to be discriminated through the mature summer crop canopy. Interpretation of the leaf-on AAA aerial photography, augmented with 2005 early spring, (leaf-off) U.S. Geological Survey (USGS), National Aerial Photography Program (NAPP) imagery determined that approximately 30 % more sinkholes are present on the land surface then are delineated on the most current USGS 7.5 minute topographic quadrangle maps of the study area. Conversely, in the densely wooded areas of the sinkhole plain, numerous sinkholes not visible on the summer 1940 AAA photography could be detected on the leaf-off NAPP photography. [ABSTRACT FROM AUTHOR]

Depending on perspective, Missouri is blessed or cursed with abundant limestone and dolomite resources. Missouri benefits economically from carbonate bedrock in the areas of mining, agriculture, tourism, and water supply. Karst terrane that locally accompanies the resource, however, brings a special set of challenges in residential and commercial development and in treating and isolating the liquid, solid, and hazardous wastes produced by humans and agricultural operations. Catastrophic sinkhole collapse is only one of the numerous risks karst poses to construction and development. Other concerns include subsidence, leaking impoundments, and rapid off-site migration of wastes. These risks should be considered logically and holistically from the beginning of the development process. Yet there are numerous reasons why karst is largely ignored in new construction. Many, if not most, in our society are largely unaware of the threats posed by development in karst settings. [ABSTRACT FROM AUTHOR]

A significant minority of sinkholes that formed in gypsum bedrock in the Delaware Basin region are of human origin. These anthropogenic sinkholes are often associated with improperly cased abandoned oil wells or with solution mining of salt beds in the shallow subsurface. In July 2008, a sinkhole formed abruptly at the site of a brine well in northern Eddy Co., New Mexico. The well operator had been injecting fresh water into underlying salt beds and pumping out the resulting brine for use as oil field drilling fluid. Borehole problems had prevented the operator from conducting required downhole sonar surveys to assess the dimensions of subsurface void space. The resulting sinkhole formed in just a few hours by catastrophic collapse of overlying mudstone and gypsum and in less than 1 month had reached a diameter of 111 m and a depth of 64 m. Fortuitously, a seismometer had been deployed 13 km southeast of the brine well a few months earlier and precursor events were captured on the seismograph record a few hours before the subsurface cavity breached the surface. Four months later, another sinkhole collapse occurred in northern Eddy Co., again associated with a brine well operation. These events prompted the New Mexico Oil Conservation Division to review its regulations regarding brine well operations in the southeastern New Mexico oil fields. A third brine well within the city limits of Carlsbad, N. Mex., has been shut down to forestall possible sinkhole development in this more densely populated area. Electrical resistivity surveys have been conducted adjacent to the Eddy Co. sinkholes to assess the potential for additional subsidence or collapse events in the future. [ABSTRACT FROM AUTHOR]

Sudden and unpredictable collapse of unconsolidated cover over soluble bedrock defines cover collapse. Cover collapse in Kentucky frequently damages buildings, roads, utility lines, and farm equipment. It has killed livestock, including thoroughbred horses, and has injured people at an estimated annual cost of $20 million. The Kentucky Geological Survey began developing a file of case histories of cover collapse in 1997 and now receives approximately 24 reports annually. The case history file contains 247 individual entries and spans some 30 years, yet is thought to represent only a fraction of the annual occurrences. The reported sites are distributed statewide but are concentrated in urban settings. The largest cover collapse recorded was in Logan County and was 15.5 m in diameter and 18 m deep. The Dishman Lane collapse in Bowling Green, KY, although larger, included some bedrock collapse. Collapse features have an average long axis length of 3.1 m and an average observable depth of 2.6 m. The ratio of the long and short axes of the collapse at ground level is 1.30. When plotted on a digitized topographic overlay showing outlines of mapped sinkholes, 11 % of the cover-collapse sites are inside a mapped sinkhole. Of a total of 124 observations that noted the presence or absence of buried trash, 10.7 % of sinkholes had trash present. Nearly 52 % of collapses are underlain by Mississippian rocks, whereas 39.7 % are underlain by Ordovician carbonates. The remaining percentage is underlain by Silurian and Devonian carbonates or lithology is undetermined. The most common months for cover collapse are April, May, and June. Continued accumulation of case histories of cover collapse in Kentucky will result in a better understanding of where, when, how, and why cover collapse occurs. [ABSTRACT FROM AUTHOR]

Until the recent economic slowdown, development in rural areas was increasing at a rapid rate in Kentucky and resulting in development pressure on less desirable lands, including large areas of karst land. Most damage caused by karst geologic hazards is from groundwater pollution, cover-collapse sinkholes, and sinkhole flooding. The economic costs of karst-related geologic hazards have been estimated to be $20 million annually in Kentucky. The Kentucky Geological Survey drafted a model ordinance to guide development in karst for the purpose of reducing economic and environmental losses from karst geohazards. The text of the ordinance provides a wide range of ideas for planning and zoning agencies to adopt as needed. The final draft of the model ordinance was completed in the fall of 2008 and went through a thorough technical and editorial review, both internally at KGS and among other karst researchers. An effort was made to find an attorney to volunteer time to review the document, but we were not successful. The decision was made to move forward and send copies to 70 fiscal courts or planning and zoning boards. It was reasoned that any adopted ordinance derived from this document would be reviewed by their attorneys, regardless of previous reviews. To date the response has been poor. Only two agencies have contacted KGS for further information. [ABSTRACT FROM AUTHOR]

El artículo considera los proyectos arqueológicos de las cuevas inundadas de la Península de Yucatán, México desde 1881. Se analizan varios procesos de excavación de los cenotes, tales como el uso de máquinas de sondeo automático, de dragas y de buceos. Se describen los estudios de la sociedad geográfica estadounidense National Geographic Society y el Instituto Nacional de Antropología e Historia de México, los cuales dataron los hallazgos en la región a la era de hielo.

The relation between sinkhole density and water quality was investigated in seven selected carbonate aquifers in the eastern United States. Sinkhole density for these aquifers was grouped into high (>25 sinkholes/100 km2), medium (1–25 sinkholes/100 km2), or low (<1 sinkhole/100 km2) categories using a geographical information system that included four independent databases covering parts of Alabama, Florida, Missouri, Pennsylvania, and Tennessee. Field measurements and concentrations of major ions, nitrate, and selected pesticides in samples from 451 wells and 70 springs were included in the water-quality database. Data were collected as a part of the US Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program. Areas with high and medium sinkhole density had the greatest well depths and depths to water, the lowest concentrations of total dissolved solids and bicarbonate, the highest concentrations of dissolved oxygen, and the lowest partial pressure of CO2 compared to areas with low sinkhole density. These chemical indicators are consistent conceptually with a conduit-flow-dominated system in areas with a high density of sinkholes and a diffuse-flow-dominated system in areas with a low density of sinkholes. Higher cave density and spring discharge in Pennsylvania also support the concept that the high sinkhole density areas are dominated by conduit-flow systems. Concentrations of nitrate-N were significantly higher ( p < 0.05) in areas with high and medium sinkhole density than in low sinkhole-density areas; when accounting for the variations in land use near the sampling sites, the high sinkhole-density area still had higher concentrations of nitrate-N than the low sinkhole-density area. Detection frequencies of atrazine, simazine, metolachlor, prometon, and the atrazine degradate deethylatrazine indicated a pattern similar to nitrate; highest pesticide detections were associated with high sinkhole-density areas. These patterns generally persisted when analyzing the detection frequency by land-use groups, particularly for agricultural land-use areas where pesticide use would be expected to be higher and more uniform areally compared to urban and forested areas. Although areas with agricultural land use and a high sinkhole density were most vulnerable (median nitrate-N concentration was 3.7 mg/L, 11% of samples exceeded 10 mg/L, and had the highest frequencies of pesticide detection), areas with agricultural land use and low sinkhole density still were vulnerable to contamination (median nitrate-N concentration was 1.5 mg/L, 8% of samples exceeded 10 mg/L, and had some of the highest frequencies of detections of pesticides). This may be due in part to incomplete or missing data regarding karst features (such as buried sinkholes, low-permeability material in bottom of sinkholes) that do not show up at the scales used for regional mapping and to inconsistent methods among states in karst feature delineation. [ABSTRACT FROM AUTHOR]

Abstract: 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 δ 13C 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. δ 13C 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. [Copyright &y& Elsevier]

Evaporites, including rock salt (halite) and gypsum (or anhydrite), are the most soluble among common rocks; they dissolve readily to form the same types of karst features that commonly are found in limestones and dolomites. Evaporites are present in 32 of the 48 contiguous states in USA, and they underlie about 40% of the land area. Typical evaporite-karst features observed in outcrops include sinkholes, caves, disappearing streams, and springs, whereas other evidence of active evaporite karst includes surface-collapse structures and saline springs or saline plumes that result from salt dissolution. Many evaporites also contain evidence of paleokarst, such as dissolution breccias, breccia pipes, slumped beds, and collapse structures. All these natural karst phenomena can be sources of engineering or environmental problems. Dangerous sinkholes and caves can form rapidly in evaporite rocks, or pre-existing karst features can be reactivated and open up (collapse) under certain hydrologic conditions or when the land is put to new uses. Many karst features also propagate upward through overlying surficial deposits. Human activities also have caused development of evaporite karst, primarily in salt deposits. Boreholes (petroleum tests or solution-mining operations) or underground mines may enable unsaturated water to flow through or against salt deposits, either intentionally or accidentally, thus allowing development of small to large dissolution cavities. If the dissolution cavity is large enough and shallow enough, successive roof failures can cause land subsidence and/or catastrophic collapse. Evaporite karst, natural and human-induced, is far more prevalent than is commonly believed. [ABSTRACT FROM AUTHOR]

Hillsborough County, Florida, is a karst region that is heavily urbanized, yet no study has been undertaken measuring the degree of human disturbance. created a hierarchical and standardized disturbance index specifically designed for karst environments. To address the problem of determining human disturbance in the county, the above index was successfully applied and it was found that Hillsborough was highly disturbed (disturbance score of 0.69 of 1.0) because of its predominant urban and rural land use. Furthermore, the application of the index allowed for its refinement and the highlighting of environmental aspects in need of remediation such as soil compaction, deforestation, disturbance of archaeological sites, and the expanding urban footprint. Several minor issues arose during the application: the need for broader indicator descriptions that encompass a variety of scenarios, the need for a revised water quality indicator, inadequate data on sinkholes, and a lack of data for species richness and species population density. The utility of the index to resource managers arises from emphasizing certain areas of the environment that require immediate attention and determining temporal changes in environmental quality. Future application of the index requires potential retooling of the biota indicators, tightening of scoring descriptions for certain indicators, and further examination of the scale at which the index can be applied. [ABSTRACT FROM AUTHOR]

Evaporites, including gypsum (or anhydrite) and salt, are the most soluble of common rocks; they are dissolved readily to form the same type of karst features that typically are found in limestones and dolomites, and their dissolution can locally result in major subsidence structures. The four basic requirements for evaporite dissolution to occur are: (1) a deposit of gypsum or salt; (2) water, unsaturated with CaSO4 or NaCl; (3) an outlet for escape of dissolving water; and (4) energy to cause water to flow through the system. Evaporites are present in 32 of the 48 contiguous states of the United States, and they underlie about 35–40% of the land area. Karst is known at least locally (and sometimes quite extensively) in almost all areas underlain by evaporites, and some of these karst features involve significant subsidence. The most widespread and pronounced examples of both gypsum and salt karst and subsidence are in the Permian basin of the southwestern United States, but many other areas also are significant. Human activities have caused some evaporite–subsidence development, primarily in salt deposits. Boreholes may enable (either intentionally or inadvertently) unsaturated water to flow through or against salt deposits, thus allowing development of small to large dissolution cavities. If the dissolution cavity is large enough and shallow enough, successive roof failures above the cavity can cause land subsidence or catastrophic collapse. [ABSTRACT FROM AUTHOR]

Reports the palynology of Peace Creek site, a sinkhole filled with sediment in Polk County, Florida. Presence of well-preserved pollens in the site; Occurrence of Pterocarya and regionally extinct taxa indicating late Neogene age; Characterization of long Pinus and short Quecus phase of upland pollen assemblage.

Presents a study which reported a diverse assemblage of plants and animals from a buried sinkhole deposit in Indiana. Geological setting of the sinkhole; Characteristics of the plant and animal fossils from the sinkhole.

Offers curriculum ideas for a Geology project about the relationship between sinkhole development and groundwater levels in Orlando, Florida. Account of a lawsuit filed in 1994; Learning objectives; Importance of geologic processes. INSET: Mining Firm Sued for Millions over Sinkhole.

Outlines the major sinkhole hazards of flooding, collapse and ground-water contamination and their attendant risks in urbanizing sinkhole terrain. Risk assessment in a planning context; Suggestions on the development and implementation of guidelines for accommodating growth and minimizing environmental impact.

Explores the effects of demographic parameters and different patterns of migration to the maintenance of genetic variability in a single sink or sinkhole population that receives migrants from a source population and whose size changes with time. Demographic equilibrium of sink with constant number of migrants; Bernoulli and Poison migrations; Demographic stochasticity.

The author of the article discusses the need to alert local, state, and national communities to the importance of rebuilding the U.S. infrastructure. After Hurricane Katrina, the Minneapolis, Minnesota bridge collapse, and numerous reports of sinkholes, blackouts, and sewage overflows, the author points out the necessity of addressing the issue of infrastructure rebuilding. The author emphasizes that lawmakers will never build a strong economy with repeated infrastructure failures.

Presents a research report on the decreased rates of alluvial sediment storage in the Coon Creek Basin, Wisconsin for the period 1975-93. Constant sediment yield (efflux); Demonstration that sediment sources, sinks, and fluxes vary over time and space.

Explores the mechanisms underlying the formation of submarine sinkholes in the Straits of Florida. Karst as the topography resulting from the chemical dissolution of carbonate rocks; Conditions prerequisite to the formation of karst features.

The article presents science new briefs as of July 2017. Topics include nomination of investment banker Paul Dabbar as undersecretary of science in the U.S. Department of Energy; a bill approved by a U.S. House of Representatives subcommittee that raised the budget for the National Institutes of Health; and an agreement on the amount of freshwater to be provided to the Palestinian Authority under the Red Sea-Dead Sea Conveyance project, which is expected to prevent formation of new sinkholes.