The mechanism of cave mining propagation still requires a better understanding to be attained outside the industry-accepted Duplancic conceptual model. While this model suggests a continuous damage profile to be followed when an orebody is undercut in cave mining operations, the research of Cumming-Potvin (2018) describes an extended conceptual model to cave propagation which highlights a different failure mechanism whereby discontinuous damage occurs through the advancing events of parallel fracturing termed `fracture banding'. In this dissertation, a physical modelling approach was adopted in an attempt to simulate the process of cave mining propagation at various stress states in order to observe the resulting failure mechanism. Four centrifuge tests were conducted utilising manufactured artificial rock material sample panels that were subjected to various ratios of horizontal to vertical stress. Before the applicability of this material to represent actual rock found in cave mines could be deemed adequate, a full characterisation of the properties of this artificial rock material was performed. The material testing included uniaxial compression strength tests, triaxial tests and Brazilian disc tests. These values were compared to typical corresponding parameters of various rock types in order to establish a suitable range of scale factors. Particle Image Velocimetry (PIV) was integrated into determining the critical extensional strain for the material which was used to establish a strain-based failure criteria for the artificial rock material using the model developed by Stacey (1981). Once the artificial rock material was manufactured to replicate the characteristics rock by a standard deemed acceptable; a scale factor range of 12 - 9 291 was achieved using an absolute critical extensional strain value of 0.014 %. The following set of conditions were achieved when conducting physical modelling: negligible horizontal confinement using sand with zero overburden pressure, minimal horizontal confinement with zero overburden pressure, maximum horizontal confinement with minimal overburden pressure, and lastly maximum horizontal confinement with maximum overburden pressure following the same proportion in lateral earth pressure (K ratio) as the previous test. Even though the results, with regard to the geometry of cave formation, in each of the tests were different; all four tests displayed an indication of `fracture banding'. In terms of the different geometries that had formed during cave progression, it was found that models with lower K ratios showed a higher development of the caving mechanism (at the same vertical stress), whilst models with higher K ratios suppresses this. Moreover, models conditioned with larger vertical stresses saw cave formation forming in a longer time period, but ultimately exhibited caves with a larger perimeter and area once the full undercut width had been reached. Total collapse occurred when the cave advanced vertically reaching the top surface of the sample through the formation of a `chimney'. On further investigation of mapping strains in models throughout common time-steps, the results showed that regions of high minor principal strains from PIV analysis of cave propagation correlated well with identified fractures. In all test cases, cracks propagated at the point of the material matching or exceeding the absolute critical extensional strain value in either new cracks opening via cave-back progression or reaching pre-existing fractures. In most cases, regions of these tensile strain values were observed to have been bisected by visual cracks in models which suggest that the perceived behaviour of parallel fracturing is tensile in nature. / Dissertation (MEng (Structural Engineering))--University of Pretoria, 2020. / Prof J. Wesseloo, Australian Centre for Geomechanics / Prof E.P. Kearsley, University of Pretoria / Civil Engineering / MEng (Structural Engineering) / Unrestricted

Thesis (M.F.A.)--Boston University. Thesis production book of William Saroyan's The Cave Dwellers, directed by Robert R. Lehan. Submitted in partial fulfillment of the Master of Fine Arts degree requirements, Boston University, School of Fine and Applied Arts, June 1963.

Three cave sites, Nelson Bay Cave on the coast, Kangkara in an intermontane valley and Boomplaas some 80 km inland in the southern Cape Province, South Africa, were excavated between 1970 and 1979. Nearly 225 000 stone artefacts from the Later Stone Age sequence dating within the last 20 000 years are described from these three sites and are related to micro- and macroevolutionary changes at a regional and sub-continental level to provide a model for change in the Later Stone Age. The classification scheme was designed to highlight inter- and intra-site variability through time and focused on analysis of the successive stages in the reduction sequence from raw material nodule to finished tool. Linear regression was used to test for interdependence and independence of variables and the significance of changes in size and shape of untrimmed flakes and scrapers was assessed. In the case of the scrapers, samples from the three southern Cape sites and from the eastern and northern Cape were compared and tested for significance with Mann Whitney and Kolmogorov-Smirnov two-sample non-parametric tests. The results indicate two levels of change through time, that involving the appearance of innovations that can be described as macroevolutionary, and that involving the subsequent modification of the frequency, size and shape of these innovations and other artefacts already part of the toolkit that can be described as microevolutionary change. By comparison with modern technological data, innovative changes represent the diffusion and acceptance of major advances in tool technology that are predictable from trends observed in modern technology. Post-innovative or microevolutionary changes, on the other hand, take the form of oscillations around a gradually changing mean that are similar to changes in style or fashion in the modern idiom. The hypothesis that technological change was stimulated by environmental change was tested by comparing the timing of technological changes with those seen in oxygen isotope ratios in a Cango Cave stalagmite, charcoals from woody plants brought into Boomplaas Cave for firewood, small mammals caught by owls and eaten at Boomplaas and Nelson Bay Cave, and larger mammals hunted by people at all three sites. The results indicate that there is no consistent relationship between changes in the stone tool technology and environmental change. There is, however, a coincidence in the timing of changes in the larger mammals hunted and the stone tool technology that took place over a relatively short span of time between 12 000 and 11 000 B.P., post-dating major environmental adjustments at the end of the last glacial cycle by some 3000 years. Technological changes that took place between 8000 and 6000 B.P. were not coincident with a change in the animals hunted, nor with an equally sudden shift in environmental data, while a change in economy from hunting to herding within the last 2000 years was not accompanied by a change in the stone tool technology although pottery was added to the toolkit. There is thus a very complex relationship between economy, technology and environmental change that is not readily predictable. The sequence in the southern Cape can be described in terms of punctuated equilibria, but the times of rapid change in technology, economy and climate do not always coincide. In the technological system periods of relative stasis have been labelled the Robberg, Albany and Wilton industries. The content, dating and evidence for subsistence during the Later Stone Age south of the Zambesi is reviewed from several hundred dated horizons at over 160 sites and although there is some spatial variability, the sequence of technological changes is much the same throughout the sub-continent. This confirms the long-held belief that the innovations that spread through the sub-continent were diffused over a very wide area of the Old World as the result of a well developed network of intercommunications during the Stone Age, while at times population migrations also took place. Microevolutionary changes, on the other hand, tend to be more regionally specific and may have been stimulated by different cues.

The Quaternary record of fossil snakes (Reptilia, Squamata) in Asia is extremely rare; any information is noteworthy. An articulated snake skeleton was recovered from the early Pleistocene (2.15–2.14 Ma) deposits in Renzidong Cave, Yangtze River Valley, east-central China. The skeleton contains about 122 nearly complete vertebrae but lacks the cranium and caudal vertebrae. Preserved vertebral characters indicate that the snake is particularly similar to the rat snake, Elaphe (Colubridae) especially with the European Elaphe praelongissima (late Miocene). We identify the specimen as cf. Elaphe sp. This genus and ‘Coluber s.l.’ are unfortunately similar and difficult to differentiate based on just vertebral comparisons of species living in Europe. Adequate comparative skeletons of living snakes of eastern Asia are noticeably absent in museums making identifications of fossil specimens less than satisfactory. Finding dated fossil remains of the snake Elaphe in Asia holds importance to the understanding of its time of dispersal between Asia, Europe and North America, but this can only be adequately examined with fossil remains accurately and satisfactorily identified.

Research on squamate evolution of Australia has predominantly focused on the eastern portion of the continent, whereas little is known about the record from Western Australia. Deposits in Devils Lair provide a glimpse of late Pleistocene Egernia group skink representation from the Cape Leeuwin-Naturaliste region of southwestern Western Australia. Previous studies of fossils from the cave indicate a peak in the number of lizard remains during the last glacial maximum, a time when mammal and charcoal remains suggest an open, dry environment. Previous studies of Devils Lair have not attempted to identify lizard remains beyond 'lizard'. Here, we identify Egernia group lizard remains as Liopholis spp., Egernia spp., Lissolepis spp. and Tiliqua rugosa, which range in age from ca 48000 to 13000 yr B.P.

The first Sinomastodon (Gomphotheriidae, Proboscidea) skull of the Early Pleistocene, collected from the Renzidong Cave deposits in Anhui Province, Eastern China, is described here as S. jiangnanensis sp. nov. As the only brevirostrine trilophodont gomphotheriid known from the Old World, Sinomastodon was mainly indigenous to China from the Early Pliocene to the Pleistocene. Compared with a few single Pleistocene teeth previously found in China, S. jiangnanensis sp. nov. is represented by a relatively complete skull, mandible and dentition, which is the first discovery of a Quaternary Sinomastodon skull from China. With a brevirostrine, elephant-like skull, no lower tusks, and simple bunodont and trilophodont intermediate molars, the new species is morphologically distinct from other gomphotheres and should belong to the genus Sinomastodon. The new species is more progressive than S. hanjiangensis and the Pliocene type species S. intermedius in its skull and mandible morphology, but is evidently more primitive than the Pleistocene S. yangziensis in its molar morphology. The faunal analysis suggests that the emergence of S. jiangnanensis sp. nov. in Jiangnan area and its southward migration may have been related to a cooling event at the beginning of the Quaternary in Eastern China.

In this study of energy pathways in karst groundwater the first chapter examines spatial and temporal patterns of bacterial density and activity in the Dorvan-Cleyzieu karst aquifer, France. During baseflow, bacterial density and activity in the water column was similar in upper and lower zones of the aquifer. Floods apparently scoured inactive bacteria from the aquifer matrix but had little effect on respiring cells. Dissolved organic carbon was more abundant at the base of the aquifer, probably because of patchy distribution of particulate organic matter in upper aquifer zones that leached dissolved organic carbon. The temporal sequence of flooding and drying in the aquifer appears to play an important role in the maintenance of biofilms which should be important energy sources to higher trophic levels in the aquifer. The ecosystem expansion and contraction model, originally developed to describe surface streams, may be a good descriptor of spatial and temporal patterns of microbial films in karst aquifers. The process of leaf and wood breakdown in cave streams in Organ Cave, West Virginia is examined in Chapter 2. Leaf and wood breakdown rates and microbial biomass and respiration on leaves and wood were compared between cave streams with and without coarse particulate organic matter (CPOM) input from the surface to examine the role of CPOM input in leaf and wood breakdown. Breakdown rate and pattern of microbial colonization of leaves and wood were typical of results reported for surface streams. Unlike in surface streams, CPOM input did not influence breakdown rate or microbial colonization on leaves and wood, apparently because nutrients are not limiting in cave streams. Nutrient addition had little effect on microbial films on wood in either stream type. Gammarus minus is an important shredder in Organ Cave streams and G. minus colonization accelerated leaf breakdown rates. Leaf and wood transport rates were low and, when combined with breakdown rates, suggest that CPOM will be retained and transformed to fine particles near its entry point to the subsurface. In chapter 3 I examine cave stream food web structure and the role various organic matter sources in stream trophic dynamics. I used stable isotope (13C and 15N) natural abundance analysis and a 13C-acetate tracer release to establish feeding relationships and to trace the use and importance of bacterial carbon in cave streams with and without CPOM input. Cave streams contained three trophic levels consisting of organic matter sources, primary consumers, and predators. Patterns of 13C labeling in the stream were similar to that in similar studies of surface streams. 13C acetate was incorporated into epilithic biofilms and fine benthic organic matter (FBOM). Some primary consumers, Fontigens tartarea, Gyraulus parvus, and Physa were highly labeled and showed a longitudinal labeling pattern consistent with the consumption of epilithic biofilms. An epigean caddisfly, Dolophilodes, was highly labeled and probably feeds on suspended organic matter. Other primary consumers, Gammarus minus and Caecidotea holsingeri, feed on FBOM and epilithon. Two amphipods, Stygobromus emarginatus and S. spinatus, and a planarian, Macrocotyla hoffmasteri, are predators in the streams. Leaves and wood were not major energy sources directly used by stream animals. Dissolved organic matter (DOM) originating from soils appears to be the primary energy source for stream food webs by fueling bacterial production that is then used by higher trophic levels. Because epilithon C turnover times were relatively long (12.7 - 17 days), DOM can be immobilized in cave stream biofilms, enhancing the efficiency with which the microbial loop may transfer energy to higher trophic levels. / Ph. D.

Master of Science - Science / The South African hominin bearing caves have yielded a wealth of early hominin and other faunal material, which has been the subject of many studies. Little work, however, has been undertaken on the cave fills themselves, as the breccias are complex, poorly stratified, highly calcified, inadequately exposed and too old to date by conventional radiometric means (Partridge, 2000). Gladysvale Cave is an exception to this, as the younger, internal deposits are well exposed from mining, are extremely well stratified, and are preliminarily dated to between 200 and 250 kyr, making this an ideal location to document the three dimensional stratigraphy and sedimentology of a cave fill fan and to test other models of cave sedimentation. The chronostratigraphic approach of Moriarty et al. (2000) was used to divide the deposit at Gladysvale into flowstone bounded units (FBU). The younger, internal deposit at Gladysvale was shown to consist of six major FBU and two minor ones, which in general occur throughout the cave. Binding flowstones are not always present, and are limited to areas directly below and in close proximity to major palaeodrip sources. The majority of sediment entered the cave through a single, central entrance and then split into two lobes around a number of stalagmitic bosses. This entrance eventually choked, and final stage sedimentation entered through a slit-like entrance across the front wall of the cave. As accommodation space inside the cave is fixed, the morphology of the units is defined by their relative position in the cave and the topography of the underlying units. Six major facies types are described, and facies changes from the proximal to distal portions of the deposit are described. Facies changes in time were controlled by the sediment supply rates. A number of intercalated flowstones and stalagmites were dated via ICP-MS Uranium-series dating, and despite problems with detrital contamination, ten reliable and robust dates were acquired, only three of which required correction for excess 232Th. The internal fan deposit is between ~570 and 7 kyr, making it both older and younger than previously thought. The dated speleothems all grew in the recovery period following a full interglacial or major inter stadial, indicating that these were periods of increased effective precipitation, during which the cave entrance was restricted to incoming clastic sediment. The dated flowstones show good concordance with the rainfall record of the Tswaing Impact Crater, and this record was used to generate an age model for the undated flowstones and intercalated breccia units. Carbon and oxygen isotope analysis of the breccias and flowstones provided further climatic control. Oxygen isotopes are invariant between flowstone and breccia, and any original signature was most likely overprinted by the residence time of the groundwater in the dolomite host rock. Carbon isotopes show more variation, and there is clear partitioning between flowstone and breccia, and ä13C values are interpreted as representing changing amounts of C3 and C4 vegetation respectively. The C4 signal for the breccias is confirmed by the presence of granular soil micropeds seen in thin sections. The succession of flowstones and breccias, the U-series dates and the stable light isotope data provide a ~600 kyr record of terrestrial climate change, which is, to date, the oldest such record for southern Africa, and shows excellent concordance with various other climate change records, both global, local and marine. The synchronicity of these records suggests a strong allocyclic control, which is attributed to changes in atmospheric circulation, in particular the size and position of the circumpolar vortex above Antarctica. A climatically controlled model for the nature and rate of sedimentation at Gladysvale Cave is proposed, in which flowstones grow during the warm, wet recovery period following full interglacials, during which C3 vegetation dominates and cave entrances are restricted. Sediments are washed into more open caves, during arid, C4 dominated conditions, corresponding to glacial periods. As this model is climatically controlled, and the Cradle of Humankind World Heritage Site is a relatively small area, the other caves in the area would have experience the same conditions, and if open at the time should contain fills of similar ages. This study has shown the value of the cave fills themselves, which are often understudied. The breccias at Gladysvale are strongly climatically controlled, being deposited only once certain climactic thresholds are crossed, hence producing a highly punctuated record. The hominin and other faunal remains from these caves should be viewed within this context. Gladysvale Cave also contains a ~600 kyr record of climate change, which will contribute to our understanding of terrestrial climatic changes and the landscape’s response to them.

The highly porous karst limestone of the Yucatan Peninsula promotes infiltration of rainwater into the subsurface, where it becomes part of the Yucatan Aquifer. The combination of high subsurface porosity, high evapotranspiration, and seasonal droughts results in relative scarcity of lakes or drinkable water at the surface. The majority of past and present people living on the Yucatan Peninsula have depended on groundwater resources for domestic purposes. Whereas coastal karst aquifers such as the one in the Yucatan Peninsula are important water resources, they are highly vulnerable to climate-related changes such as sea level (SL) rise, increased hurricane intensity and extended droughts. With ongoing development along the eastern coast of the Yucatan Peninsula (Quintana Roo), predicted increases in storm intensity, and rising population and potential pollutant output, it has become imperative to study the seasonal and long-term effects of climate and human activity on the Yucatan Aquifer. Like many coastal karst aquifers, the Yucatan Aquifer is stratified according to density, with the Meteoric Water Mass (MeWM) flowing towards the coast on top, and the Marine Water Mass (MaWM) flowing inland on the bottom. The current basis of our knowledge about how the two water masses interact has been from short-term instrumental monitoring and numerical modelling, which is useful for understanding straightforward relationships between salinity, precipitation and temperature across the two water masses and have paved the way for more complex analyses to be completed using the simple principles to guide geochemical studies of sediment within the systems. Generally, sediment cores have been analysed discretely using various methods including grain size analysis, micropaleontology, WD-XRF, and others, however the recent rise of µXRF Core Scanning provides a quicker, more cost effective and higher-resolution method for studying climate-related patterns in sediment cores. This thesis outlines and provides robust evidence for three new methods of using µXRF-CS to determine past and present climatological changes and their relationship to sediment elemental counts. We provide the first outline of the seasonal and spatial controls of geochemical changes in sedimentation in a coastal cave system (Yax Chen), using four years of in situ sediment collection. We then provide the first calibrated record of past salinity based on Cl counts within sediment cores taken from shallow lakes. Although instrumental monitoring has provided evidence that the aquifer is impacted by modern wet and dry periods, the effect of past climate on the aquifer has not been investigated. We provide the first record of water-column mixing at three locations within coastal Quintana Roo. This demonstrates that there has been a long-term climate impacts to coastal Yucatan Peninsula groundwater, which may be scaled to other karst islands and provides evidence that increased hurricane frequency and/or magnitude could change the baseline salinity of the fresh MeWM. / Dissertation / Doctor of Philosophy (PhD) / The porous limestone (karst) geology of the Yucatan Peninsula results in percolation of rainwater down into the subsurface where it is held in the vast Yucatan Aquifer that past and present people have depended on for water resources. Such aquifers are highly vulnerable to human activity and also climate change via increased sea level rise, hurricane intensity and droughts. The Yucatan Aquifer is made up of two separate water masses that have different salinities, and can interact physically and chemically due to changes in climate and weather. Sediment cores can be used to look at subannual geochemical changes which reflect long term behaviour of the aquifer, but first the relationship between sediment change and climate must be established. This thesis uses an iTRAX X-Ray Fluorescence Core Scanner (XRF-CS) to investigate changes in surface water and groundwater over the past 6000 years, and provides the first record of rainfall-induced mixing in a coastal karst aquifer. We also provide evidence of rapid salinity change in shallow lakes associated with intense dry periods, and reveal relationships between cave sedimentation and surface vegetation coverage.

Cave systems and their unique biota are widely viewed as highly endangered, yet very little is known about basic life history, ecology, distributions, habitat requirements, and evolutionary relationships of subterranean species. The crux of the problem in cave studies is the assumption that traditionally defined morpho-species represent distinct evolutionary lineages. Convergence is exhibited in the morphologies of many animal groups, vertebrate and invertebrate, which leads to confusion in diagnosing species' boundaries, geographic distributions, gene flow routes, and imperilment. This dissertation research includes phylogeographic analyses of freshwater cave-dwelling crayfishes in the Southern Appalachians, a global hotspot of subterranean biodiversity. By examining population structure in light of habitat, geology, geography, and hydrology, we can better provide conservation direction for these groundwater species. Chapter one introduces a method, Nested Clade Phylogeographic Analysis (NCPA), used to investigate hypotheses about historical and current population structures within species. Using a statistically-testable framework, NCPA can elucidate historical speciation patterns and current routes of gene flow using genetic sequence data of thoroughly-sampled species. Using diverse examples, the chapter details the methodology of building haplotype networks, performing the geographic analyses, inferring past and contemporary evolutionary patterns and processes, and delineating species' boundaries. Chapter two examines two competing hypotheses regarding conservation status of cave-dwelling species using a wide-ranging group of obligate subterranean crayfish species on the Cumberland Plateau's western escarpment. Using a population genetic approach, cave crayfish exhibited moderate to high levels of genetic diversity and attained large population sizes over their evolutionary histories. Phylogeographic analyses revealed that this crayfish assemblage originated along the northern end of the Cumberland Plateau and in leading-edge small steps, colonized southward and accumulated diversity along the way. Current species' boundaries do not match traditional morpho-species designations and also do not match current hydrological units. Chapter three explores phylogeography and habitat differences within the facultative cave-dwelling crayfish species Cambarus tenebrosus. This freshwater species is unique in that it inhabits surface and subsurface karst environments, has an unusually large distribution, and exhibits troglomorphism with reduced eyes and elongated limbs. Using sequence data from over 100 sampled localities, mostly along the Cumberland Plateau, C. tenebrosus appears to have inhabited surface and subsurface biomes throughout its evolutionary history. Additionally, this species shows extremely high levels of genetic diversity and NCA revealed significant phylogeographic structure within the species, but there was no significant relationship between habitat and genetic structure. Chapter four examines the obligate cave crayfish assemblage, genus Cambarus, subgenus Aviticambarus, which ranges across the southernmost area of the Southern Appalachians, which is known to contain the highest species diversity of obligate terrestrial animals in the United States. The Aviticambarus assemblage is only currently known from 58 caves in Alabama and Tennessee, and with samples from half of the known sites, this study uncovered additional lineages previously obscured by convergent morphology. These species show low levels of genetic diversity and populations that do not appear to be expanding. Species' boundaries are supported by geologic and phylogeographic information, but not current drainage basin boundaries.