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Many lava tunnels are found in the Western District of Victoria, associated with volcanic eruptions of Pleistocene to Recent age, and some are probably only a few thousand years old. All Australian volcanoes are now extinct, but the most recently active were probably erupting up to 5,000 years ago, that is after the arrival of the Australian aboriginal. The newness of the Victorian caves results in original features being preserved in fine detail. All known lava caves have now been surveyed, mainly by members of the Victorian Cave Exploration Society.
Various geomorphologists such as Bögli, Corbel and Lehmann have in recent years demonstrated the interest that certain simple chemical analyses of natural waters can have for the comparison of rates of limestone solution in different in different climatic conditions. They can also have their relevance for the tracing of underground water connections as Oertli (1953) has shown in the example of the Slovenian part of the classical Yugoslavian karst. Since 1957, the writer has therefore been making such analyses of waters from Australian limestone areas. The chief significance of these measurements comes when one caving area is compared with another. M.M. Sweeting (1960) has already commented briefly on observations from Mole Creek, Tasmania, Buchan, Victoria and the Fitzroy Basin, Western Australia, made in 1958-59 by herself and the writer; further discussion will appear in a forthcoming publication of ours on the Limestone Ranges of the Fitzroy Basin. Nevertheless measurements of this kind can have a certain intrinsic interest as it is hoped to show in the following notes on the few observations I made at Yarrangobilly. These observations are set out in tabular and Trombe graph forms; the locations of the collecting points are shown on the map.
The basic textbooks and reference sources in speleology (Kunsky, 1954; Trombe, 1952 and Warwick, 1962) describe the process of solution of carbonate rocks in terms of the system CaCO3 - H20 - CO2, making little or no reference to the role of MgCO3 in the solution process. The widespread occurrence of dolomitic rocks amongst the older sedimentary formations of Australia, e.g., at Buchan, Victoria, and Camooweal, Queensland, makes some knowledge of the complexity of solution processes in rocks containing dolomite highly desirable for the understanding of the development of caves in this continent. This paper is intended to review the scattered literature on this topic and to describe what is known of the behaviour of the system CaO - Mg0 - CO2 - H20.
Eight breeding Caves of Miniopterus schreibersi (Kuhl) are described from South Australia, Victoria, New South Wales and Southern Queensland, in terms of their structure, the location of nursery areas at which juveniles are deposited after birth, and their physical environments. Maternity colonies are found at these caves through spring, summer and early autumn. Established colonies range from about 15,000 to 200,000 bats at peak size. These individuals are predominantly adult females and their young. Adult males are conspicuous only at the single South Australian breeding cave. Births occur from approximately the beginning of December to mid-January at all colonies except that in South Australia, where a birth period is evident between mid-October to late-November. Artificial warming, as a consequence of bat activity, appears to be characteristic of these Miniopterus schreibersi breeding caves. It is suggested that this may have functional significance in facilitating adequate development of juveniles, and that the habit could be a reflection of the tropical ancestry of this species.
Underground streams occur in valley floors on acid igneous rocks over a wide area of eastern Victoria. In some cases the underground passage is capable of accommodating all streamflow levels so that there is no active surface channel. Three of them contain passages accessible to cavers. The literature contains very few references to features of this kind and there is some confusion as to whether they should be called 'pseudokarst'. Detailed descriptions and diagrams are presented for two of the sites, Labertouche and Brittania Creek. At North Maroondah, sinking streams on dacite have caused complications for hydrological experiments. Possible origins of these features are discussed and it is obvious that several mechanisms are feasible. One of the difficulties in determining modes of formation is that a variety of processes could lead to very similar end products. Three main theories on the mode of formation are suggested.
Trials of the method of estimating the aggressiveness of karst water by artificial saturation (Stenner, 1969) were made on stream and spring waters in limestone country at Buchan, Victoria. Saturation was brought about with both laboratory reagent grade calcium carbonate and also with powdered local limestone. Resulting estimates of the initial degree of saturation varied considerably. The differences amounted to an average 5.6% (maximum 8.0%) in aggressiveness estimated from change in total hardness, 8.8% (maximum 14.0%) using calcium hardness, and 9.4% (maximum 31.0%) using magnesium hardness. Whilst the average difference between the two sets of results are not great, and certainly do not prohibit the use of the original Stenner method, they do serve to indicate that in particular individual cases misleading results can be obtained if local limestone is not used. Possible reasons for the differing behaviour of the two materials is suggested.
Taylor Creek Cave is formed within sediments of the Red Bluff Sand, a Pliocene unit overlain by Newer Volcanics. The cave consists of a single low chamber, 12m long and 5m wide, that has been excavated in friable sandstone under a resilient silcrete roof; it has formed by an unusual combination of piping and stream erosion. Taylor Creek initially exposed the silcrete surface, then piping below the silcrete caused tunnel formation in the sandstone. Collapse of overlying material into this tunnel captured Taylor Creek, causing it to flow beneath the silcrete and thereby enlarge the cave to its present size.
The 200,000 square kilometre Nullarbor Plain is a largely and relatively inhospitable tract of semi-arid land on the southern coast of Australia. It is also one of the world's largest and probably oldest karst landscapes. It contains a substantial number of caves, some of them very large. The sheer size of the plain together with its lack of surface water have made it a powerful ecological, physical and psychological barrier to the dispersal of evolving plants and animals and to human trade, settlement and communications. Because the plain is otherwise easily perceived as featureless, the more obvious of the caves have played an unusually prominent part in human exploration and occupation of the region. Aboriginal prehistory of cave exploration and use extends over many millenia. Two themes are especially interesting: quarrying underground as one of the earliest, and the role of water and shade in an inhospitable environment as the most persistent. The advent of European, Afghan and other cultures on this part of the southern coastline during the last four centuries has diversified the relevant historic themes. Victorian British discovery and exploration is the first stage in modern recognition of the caves, although long after the region was first discovered. The next and perhaps most remarkable phase brings together developments in Australian aviation and the adaptation of a grounded mariner to the land and air. Eventually the action moves on to the development of organised speleology. Other sub-themes in human interactions with the caves in this large waterless area include what may turn out to be either art or vandalism. They also include attempted grand solutions to the problem of water, by improbable engineering, as well as adventures of tourism, recreation and science.
The relative significance of straw speleothem growth from evaporation and from CO2 degassing was determined in Lilli-Pilli and Moons Caves (Buchan, Victoria) from a seven-month study of cave climate and water chemistry. The relative importance of these two mechanisms was inferred from the calculation of the straw growth rates according to a degassing model and an evaporation model. The modelled straw growth rates from the carbon dioxide degassing model were on hundred to one thousand times those attributable to evaporation. A third model was used to calculate straw growth rates from the overall supersaturation of the water. Growth rates were found to be within the range of 0.01 to 0.07mm per annum.
Karst features occur in Pleistocene aeolian calcarenite dunes at Bats Ridge near Portland, Victoria. The surficial and underground features show that the caves are sinuous shallow systems often with a number of entrances. Passage shape is often modified by collapse. Characteristic features such as speleothems, clastic sediments, solution pipes and foibes are described, especially "moonmilk". Syngenetic karst processes are briefly discussed.
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