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The drought culminating in 1967-68 opened water-traps in Murray Cave, thus permitting the re-exploration and survey in January 1968, of a further 1,000 feet of the main passage. Previous explorations, of which oral tradition persisted, are known to have taken place in 1902-3 and some details of the early visitors are presented. The characteristics of the extension are predominantly shallow phreatic in nature and about half of it episodically functioning in this way at the present time; the water-traps along it are inverted siphons in the strict sense and located at the sharpest changes in cave direction. The exploration limit consists of a rockfall beneath a doline, which appears, therefore, to be at least in part a collapse doline. Beneath two other dolines the cave has no sign of collapse, though tall avens reach towards the surface; these dolines are due to surface solution only. The forward part of the cave is overlain by a short, steep dry valley; the relationship between the two remains problematic but there is good reason not to regard the dry valley as the determinant of the cave's location. The evidence is now stronger for an earlier hypothesis that the cave was formerly the outflow cave of nearby River Cave, a perennially active stream cave. It also seems likely that the episodic activity of Murray Cave is due to flood overflow from River Cave. The hydrological regime of the cave is compared with precipitation records of the nearby stations. The episodic flow through the cave does not require an abnormally wet winter; it can follow fairly quickly after complete emptying of the water-traps and approaches an annual event. Draining of the water-traps is a much less frequent event, but whether a series of low rainfall years is necessary, or a single pronouncedly dry year is sufficient to achieve this, cannot be determined from available data. On either count, it seems probable that the cave opened up two or more times between the known occasions of 1902-3 and 1968 in the period 1909-53 when the cave was visited infrequently.
River Cave is a Zwischenhohle (between-cave) in which the active river passage is reached through a former tributary stream passage from a dry valley. Now vadose in character, it is of gentle gradient, with some normally and some temporarily water-filled reaches of shallow phreatic nature. There is only a single level of development. Water tracing has confirmed previous inferences that it is mainly fed from the South Branch watersink, that its normal flow goes to the Blue Waterholes, the main rising of the Plain, and that there is flood overflow to Murray Cave, which is shown to have been formerly the normal outflow cave of the system. In the changeover from one outflow point (Vorfluter) to another, a shorter, steeper cave and longer surface course has been replaced by a longer cave of shorter gradient. Ev's Cave, a flood inflow cave of the South Branch, may also feed River Cave and Keith's Faint Cave is inferred to be part of the link between South Branch Sink and River Cave. It has the aspect of an early stage of vadose development from phreatic conditions. Previous interpretation of Glop Pot as a true phreatic relic is maintained in the light of new facts. Evidence is lacking with which to date the caves at all reliably. Glop Pot possibly belongs to a phase of surface planation of Tertiary age whereas the other caves are likely to be consequent on Pleistocene dissection. The tributary passage of River Cave and its associated dry valley may have lost their stream in the Holocene when Murray Cave became intermittent in action also. The Murray Cave event is due to subterranean piracy associated with rejuvenation whereas the loss of the tributary stream is probably in part due to increasing warmth and less effective precipitation.
Kitava is the most easterly island of the Trobriand group. It is an uplifted coral atoll, oval in plan, with a maximum diameter of 4 1/2 miles. The centre of the island is swampy and surrounded by a rim that reaches a height of 142 m. Caves occur in various parts of the rim and several have been described in a previous article (Ollier and Holdsworth, 1970). One of the caves, Inakebu, is especially important as it contains the first recorded cave drawings from the Trobriand Islands. Inakebu is situated on the inner edge of the island rim at the north-eastern end of the island. Map 1 shows the location of the cave on Kitava Island. Map 2 is a plan of the cave, surveyed by C.D. Ollier and G. Heers. The location of the cave drawings is shown on the plan. Inakebu is a "bwala", that is a place where the original ancestor of a sub-clan or dala is thought to have emerged from the ground. The bwala tradition is common throughout the Trobriands and neighbouring islands. It has been described by many writers on the anthropology of the area, and was summarised in Ollier and Holdsworth (1969). The people believe that if they enter such places they will become sick and die. Until November, 1968, no member of the present native population had been in the cave, though there is a rumour that a European had entered it about 20 years before, but turned back owing to lack of kerosene. It must be admitted that this tale sounds rather like the stories one hears in Australia that Aborigines were afraid of the dark caves and therefore did not go into them. In fact, the many discoveries in the Nullarbor Plain caves show that they did, and the cave drawings in Inakebu show that someone has been in this cave. The point is that it does not seem to be the present generations who entered the caves but earlier ones; people from "time before" as they say in New Guinea. The first known European to enter the cave was Gilbert Heers, a trader in copra and shell who lived on the nearby island of Vakuta. He went into the cave on 8 November 1968 accompanied by Meiwada, head of the sub-clan associated with Inakebu, who had never been inside before. Heers and Meiwada investigated the two outer chambers but then turned back because they had only poor lights. They returned with better light on 15 November. Since they had not become sick or died, they then found seven other men willing to accompany them. They found the narrow opening leading to the final chamber, and discovered the drawings. None of the men, many of whom were quite old, had ever seen the drawings or heard any mention of them before. The drawings are the only indication that people had previously been in this deep chamber. There are no ashes or soot marks, no footprints, and no pottery, bones or shells such as are commonly found in other Trobriand caves, though bones and shells occur in the chamber near the entrance. With one exception, the drawings are all on the same sort of surface, a clean bedrock surface on cream coloured, fairly dense and uniform limestone, with a suitably rough texture. Generally the surface has a slight overhang, and so is protected from flows or dripping water. On surfaces with dripstone shawls or stalactites, the drawings were always placed between the trickles, on the dry rock. We have found no examples that have been covered by a film of flow stone. The one drawing on a flow stone column is also still on the surface and not covered by later deposition. A film of later deposit would be good to show the age of the drawings, but since the drawings appear to have been deliberately located on dry sites the lack of cover does not indicate that they are necessarily young. There are stencil outlines of three hands, a few small patches of ochre which do not seem to have any form, numerous drawings in black line, and one small engraving.
After brief descriptions of the geomorphology of the Cooleman Plain karst and in particular of the Blue Waterholes, the methods adopted to analyse the functioning of these major risings are detailed. The discharge regime of Cave Creek below them is oceanic pluvial in type perturbed by drought and snow. There is much annual variation both in seasonal incidence and total amount, with catchment efficiency correspondingly variable. Suspended sediment concentration is even more erratic and monthly determinations are inadequate for calculating corrasional denudation rates. Mean concentrations of suspended solids are about 1/18th of solute load. Total dissolved salts have a strong inverse relationship with discharge, and mean values are high compared with those for other catchments in eastern Australia but none of these determinations are from limestone catchments. Sodium, potassium, and chlorine contents are low compared with the same catchments but silica is relatively high. The ratio of alkaline earths to alkalis indicate that Cave Creek carries carbonate waters and there is an inverse regression of the ratio on discharge. There is inverse correlation of total hardness on discharge likewise due to concentration of surface waters by evaporation in dry periods, together with reduced underground solution rate at times of large, rapid flow. The spring waters remain aggressive. Close regressions of hardness on specific conductivity now permit the latter to be determined in the place of the former. Much evidence converges to indicate that all the springs at the Blue Waterholes are fed from the same conduit. The intermittent flow which comes down the North Branch on the surface to the Blue Waterholes differs significantly in many characters from the spring waters. Rates of Ca + M carbonate equivalent removal vary directly with discharge since hardness varies much less than does water volume. These gross rates have to be adjusted for (a) atmospheric salts entering the karst directly, (b) peripheral solute inputs from the non-karst two-thirds of the catchment and (c) subjacent karst solution before they can be taken as a measure of exposed karst denudation. The methods for achieving this are set out. The total corrections amount to about one third of the total hardness, though the correction for subjacent karst on its own lies within the experimental error of the investigation. The residual rate of limestone removal from the exposed karst also shows a winter/spring high rate and a summer/autumn low rate but the seasonal incidence and annual total varied very much from year to year. In comparison with results from karsts in broadly similar climate, the seasonal rhythm conforms and so does the high proportion (78%) of the solution taking place at or close to the surface. This reduces the importance of the impounded condition of this small karst but supports the use of karst denudation rate as a measure of surface lowering. Cave passage solution may however be more important in impounded karst than its absolute contribution might suggest, by promoting rapid development of underground circulation. The mean value of limestone removal is low for the climatic type and this is probably due to high evapotranspirational loss as well as to the process of eliminating atmospheric, peripheral non-karst and subjacent karst contributions. The difficulties of applying modern solution removal rate to the historical geomorphology of this karst are made evident; at the same time even crude extrapolations are shown to isolate problems valuably.
During 1971, members of the University of N.S.W. Speleological Society (UNSWSS) were working on a project to determine water table levels, as represented by sumps, in some of the Bungonia Caves. It was soon realised that the accuracy of heights determined from the available surface surveys, usually "forestry compass" traverses, was insufficient. The author was asked to provide more accurate surface levels and, consequently, two trips were organised on 24-25 July and 31 July 1971 with the aim of establishing a differential levelling net in the plateau area. Personnel on the first trip comprised E.G. Anderson and A.J. Watson (Senior Photogrammetrist, N.S.W. Lands Department), surveyors, and A.J. Pavey and M. Caplehorn, UNSWSS, assistants. On the second trip, M. Caplehorn was replaced by A. Culberg, UNSWSS.
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