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(of parts I and II) The Borenore Caves, west of Orange, occur in a partly metamorphosed Silurian limestone outcrop of about 5.5km2 which forms an impounded karst. Both of the main caves, the Arch Cave and the Tunnel Cave, contain large quantities of clastic sediments. Evidence from the position and kind of sediments and from the bedrock features show that both caves have undergone a predominantly fluvial development by a sequence of stream captures. The same type of evidence indicates a dry climatic phase for the Borenore area about 28,000 BP.
Wellington Caves, New South Wales (figure 1), have attracted scientific attention for more than a century, largely through discoveries in the cave sediments of bones from extinct animals. These bone discoveries provided impetus for a number of early speculations about the geomorphology of the caves area and its relationship to the caves. Notable among these was the conjecture of Mitchell (1839) that the valley floor sediments of the Bell River and the cave fills had been deposited during a marine transgression about one million years ago. The first systematic geomorphological work was carried out by Colditz (1943), who argued for two distinct relict erosion levels in the Bell Valley; the older level was assigned to the Lower Pliocene and the younger to the Upper Pliocene. Colditz considered that these levels provided evidence for two phases of uplift in late Tertiary times. More recently Frank (1971) made detailed studies of the cave sediments, and devoted some attention to landscape evolution. He believed that the Bell River had been captured by Catombal Creek, during the late Pliocene or early Pleistocene.
The sedimentary history of the Walli Caves began with the deposition of finely laminated clay during the latter part of bedrock development in the phreatic zone. After aeration and entrance development, entrance facies accumulated, and this was followed by the deposition of large amounts of fluvial and lacustrine deposits. Episodic fluvial erosion of these deposits then took place, and flowstone was formed extensively during periods between each active erosion phase to produce a striking sequence of suspended flowstone sheets.
Frustration and New Year Caves are active between-caves, paralleling in plan and profile the ephemeral stream bed of the V-shaped valley in which their entrances are found. The main streamsink in this valley system feeds their stream, which in turn supplies Zed Cave, a short outflow cave just outside the mouth of this valley. This modest derangement of surface drainage pattern is in keeping with the caves which show slight vadose modification of epiphreatic cave development. Although these active caves are young, they probably formed prior to a Late Pleistocene cold period (30,000 to 10,000 BP) on the basis of soils evidence. Clown Cave on the brow of the valley, a dry cave with indications of sluggish phreatic development, is related to a planation phase of Middle or Lower Tertiary age before valley incision. Bow and Keyslot Caves are abandoned in and out and outflow caves respectively, formed when the surface stream channel was a few metres above the present valley bottom so they antedate the active river caves a little. This hydrologically independent part of the Cooleman Plain mirrors in most respects the major parts draining to the Blue Waterholes, differing chiefly in the greater proportion of between-caves discovered so far.
The Abercrombie Caves are exemplary of a subterranean meander cutoff. The bedrock morphology, especially flat solution ceilings, permits reconstruction of an evolution from slow phreatic initiation to epiphreatic establishment of a substantial throughway, followed by progressive succession to vadose flow and phased channel incision. At two separate stages, there was twofold streamsink entry and underground junction of flow. Five 14C dates from alluvial sediments show that capture of the surface stream was certainly complete before c.15,000 BP and that by c.5,000 BP the stream had almost cut down to its present level.
Isaacs Creek Caves are situated in the Hunter Valley of New South Wales and form a distinct unit within the Timor karst region. The larger caves such as Man, Helictite and Belfry all show evidence of early development under sluggish phreatic conditions. Nevertheless later phases of dynamic phreatic and vadose development occurred in Belfry and Helictite caves. In the case of Helictite Cave sluggish phreatic, dynamic phreatic and vadose action may have operated simultaneously in different parts of the same cave. After each cave was drained through further valley incision by Isaacs Creek, extensive clay fills derived from surface soil were deposited in it. There has been considerable re-excavation of the fills; in Main Cave younger clay loams have partially filled the resulting cavities and thus underlie the older clays. The earliest speleogenesis took place in Main Cave which pre-dates the valley of Isaacs Creek. This cave now lies in the summit of Caves Ridge about 100m above the modern valley floor. Helictite and Shaft Caves formed when the valley had been cut down to within 30m of its present level and some early phreatic development also took place in the Belfry Cave at this time. Later phases of dynamic phreatic and vadose development in Belfry Cave occurred when the valley floor lay about 12m above its present level and can be correlated with river terraces at this height. Evidence from cave morphology, isotopic basalt dates and surfaces geomorphology indicates that Main Cave formed in the Cretaceous and that Helictite Cave, Shaft Cave and the early development in Belfry Cave date from the Palaeogene. Although the dynamic phreatic and vadose action in Belfry Cave is more recent, it may still range back into the Miocene. This is a much more ancient and extended chronology than has hitherto been proposed for limestone caves and is in conflict with widely accepted ideas about cave longevity. Nevertheless evidence from Isaacs Creek and other parts of the Hunter Valley indicates that the caves and landforms are ancient features and thus notions of cave longevity developed in younger geological environments of the northern hemisphere do not apply in the present context.
Seventeen blind valleys of the Yarrangobilly karst are describes especially with reference to shifting streamsink location and phases of downward incision. A series of measures of them, based partly on ground traverses and partly on contoured maps, is presented and discussed. Standard morphometry of the basins ending in the blind valleys is presented also. These truncated basins are shown to have normal morphometric relationships. Whether a stream sinks or not in the limestone appears generally to relate to the length of limestone to be crossed in relation to full stream or basin length, though basin relief ratio may intervene. The hypothesis that there will be dynamic equilibrium between the dimensions of blind valleys and sinking stream catchments finds only limited support in the data. This is because underground stream capture represents an abnormal event in drainage basin development liable to upset equilibrium relationships and its timing may be adventitious in that development. With a larger population of blind valleys to be analysed, this factor of timing might become subordinate, and a batter predictive model of blind valley volume be derived.
Damawewe Cave is a cave formed in Quaternary limestone near Alotau, Papua New Guinea. It consists of three sets of passages: the uppermost (and oldest) are the largest and the lowermost (active) are the smallest. Although the cave is mainly vadose, there is evidence of enlargement by corrosion and by collapse (in the uppermost level), and the sequence of cave formation has been interrupted by at least one phase of cave fill by clay and gravels.
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