"The Conservation of the West Kimberley Karst" by Adrian Davey
Published in The Western Caver Volume 20 Number 2 pp 35 -48 (1980)

Introduction

As the heading indicates this is a fairly old publication but unfortunately it is still fairly accurate with respect to the caves of the Kimberley Karst. Until the trip of Brian Vine (1996, Unpublished results) which added 70 "new" caves and karst features to the know caves of the Kimberley, very little has occurred since this publication. The cave fauna of the region has been collected by two expeditions, Bill Humphreys, pers. comm., and the recent Vine 1996 expedition. The results of these collections has not yet been published but the interesting nature of the cave fauna will be shown once these publications are completed.

Two sections from the above publication are provided here to allow the reader to understand the nature of the Kimberley karst, its caves and cave fauna. Section 3 examines the karst resources of the Kimberley karst and Section 4 briefly examines the known cave fauna of the Kimberley in 1980.

Photographs and some maps resulting from the recent Kimberley trip will be added to this information as soon as it is available.

Intro by Rauleigh Webb


RESOURCES

Geology

The Devonian reef complexes which now make up the Limestone Ranges are among the best preserved ancient reef complexes known in the world (Playford 1976). The reef complexes grew during the Middle and Upper Devonian periods along the southwestern shore of an ancient landmass, and around islands and promontories adjacent to it.

Four basic facies are recognised in the reef complexes - the back-reef, reef, fore-reef and inter-reef facies (Playford and Lowry 1966). The reef facies occurs as a narrow rim around limestone platforms of the back-reef facies; the platforms are flanked by fore-reef deposits with steep depositional dips, interfingering into surrounding inter-reef deposits (Playford and Lowry 1966). The reefs were variously formed as barrier reefs, fringing reefs, or atolls (Playford and Lowry 1966). The reef complexes remain substantially undisturbed by tectonic movements (Playford and Lowry 1966).

The stratigraphic and palaeontological literature on the Devonian rocks of the area is very extensive. Teichert (1949), Playford & Lowry (1966) and Playford (1976) list many papers involved, but there are numerous more recent papers still. The interpretation of the Limestone Ranges as more-or-less undisturbed reef complexes has recently been challenged by Logan & Semeniuk (1976). Geologically, the area remains an internationally interesting one.

Two other kinds of limestone areas occur in the southern Kimberley region. The first are the younger limestones of the off-shore islands and elsewhere. Although some are of importance as an environment for bats, none demonstrate significant karst landscape features on a-wide scale. We consider that adequate attention has been given in the report to these areas (even though the extent to which limestone occurs is incidental to the present recommendations). However, the relative lack of karst landscape either here or on the Cambrian limestones referred to below, underlines the importance of the landscape qualities of the Devonian limestones.

The second comprises the Cambrian limestones found in the Lissadell area of the East Kimberleys, and described by Shannon (1969). This area probably only contains relatively small caves, but these are clearly of archeological importance. It is suggested below that this area should be examined in the course of the further survey of caves and karst features which is proposed both by the CTRC and in extended form below...

Geomorphology

Geomorphic Setting

The karst landforms of the West Kimberley are developed as a result of dissection of an old (?Tertiary) planation surface.. The dissection has given rise to a considerable diversity of minor surface solution features, and to some particularly interesting major landforms. Undissected remnants of the old planation surface remain in a substantial area on the Oscar Plateau, and in a small area near the western end of the Napier Range.

Surface Solution Sculpture

Few areas on the dissected karst have any soil development. It is predominantly a bare karst, and most of the exposed rock exhibits surface solution sculpture. This includes vertical and near vertical fluting (rillenkarren), solution runnels (rinnenkarren), solution gullies, and rainpits. Flatter areas are characterised by flat solution pavements, grikes (enlarged joints) and solution pans. Many superb examples of these fascinating features occur at Windjana Gorge, Geikie Gorge, near Barnet Spring, and at various other places in the Napier, Oscar, Emanuel and Lawford ranges (Jennings & Sweeting, 1963a).

Karst Corridors, Giant Grikeland

Of the major landforms, perhaps the most distinctive (at an international level) are the complexes of karst corridors and grikelands narrow vertical walled canyons formed by solutional enlargement of joints in the limestone (Jennings & Sweeting, 1963a). There are frequently two joint sets intersecting approximately at right angles, resulting in a complex maze of intersecting corridors and narrow fissure caves. Perhaps the outstanding example of these is just to the east of Geikie Gorge, but there are other impressive examples near Windjana Gorge, Cave Spring and elsewhere. Enlargement of the corridor networks gives rise to impressive integrated box-valley systems, best illustrated in some of the tributary valley systems off Geikie Gorge. The cave systems at Cave Spring are developed along the course of a complex box-valley system which flows through three separate cave complexes, and is surrounded by grikelands and minor tributary box-valleys (Lowry, 1967 and Jennings & Sweeting, 1963a).

Marginal Amphitheatres

Another of the major features formed primarily by solution along joints and subsequent enlargement are the "marginal amphitheatres" - flat-floored valleys which extend into the ranges from a gap in their outer wall by extension of the surface of the marginal plain (Jennings & Sweeting, 1963a). The outstanding example is Brooking Yard, a few hundred metres southwest along the cliff from the mouth of Brooking Gorge. Other good examples occur on the southern flanks of the Pillara Range, at the Morown Cliff, and further southwest of Brooking Yard.

Tower Karst

Solutional enlargement of the level of the marginal plain results in the transition from giant grikeland and box-valleys to areas of separated towers with a flat surface between. This "tower karst" is up to 50 m tall in places, and every stage in transition from karst corridor network to that of scattered towers is represented in the Limestone Ranges. Some of the best examples - and very impressive scenery at that - are in an area to the southwest of JK Yard on Fossil Downs Station, and at Castle Rocks in the Guppy Hills (Jennings, 1962).

Pediments

The planation surface at the base level of the tower karst, marginal to the limestone cliffs, and extending out onto the plain away from the limestone, is, in fact, a pediment surface. The pediments of the Limestone Ranges are of special interest because of their development (Jennings & Sweeting, 1963a, Mabbutt, 1977 and Sweeting, 1972). There are numerous fine examples, especially along the margins of the Napier and Oscar Ranges. Pedimentation has made an important contribution to the abruptness of the cliffs along the ranges.

In some cases, there is a rock fan at the foot of the cliff, at the margin of the pediment (Jennings & Sweeting 1963a); these unusual geomorphic features have not been recorded elsewhere in Australia, and good examples occur along the northeastern flank of the Pillara Range, and on the Oscar Range a few kilometres southwest of Brooking Yard.

Other interesting features which occur away from the limestone cliffs on partly mantled pediment between JK Yard and Champagne Bore are pseudo-anticlines developed in caliche. These are a quite unusual feature - no others are known in Australia - and of some geological and geomorphological interest (Jennings & Sweeting, 1961). They contribute significantly to a better understanding of the local stratigraphy and geological structure.

Gorges

Perhaps the most widely known of the geomorphological features of the West Kimberley are the gorges. The watergaps at Geikie Gorge and Windjana Gorge, formed by the superimposition of a stream onto the geological structure, are well known. There are many other fine watergaps in the Limestone Ranges, the most impressive of which are the Brooking and Mount Pierre (Galeru) Gorges. Although shorter than the others, Mount Pierre Gorge has the highest cliffs, and is scenically very impressive.

Some of the wind gaps (e.g. Menyous Gorge) are dry gorges formed by capture of the stream. Others (e.g. Carpenter Gap) are pediment passes, formed by the meeting of pediment embayments from each side of the range.

Caves

The most numerous kind of caves in the Limestone Ranges are the cliff-foot caves. These are usually developed at or near spring outflows, and their enlargement (and elongation along the cliff-line) may be due to cliff collapse and diversion of the springs. The best documented examples are the Wangahinnya Caves near Barnet Spring (Basedow, 1918 and Jennings & Sweeting, 1963a) and at such places as Elimberrie Spring and Siphon Spring, but there are numerous others (usually fairly small, e.g. many of the caves mentioned by Playford, 1960).

One of the most interesting of the caves in the area is The Tunnel which penetrates right through the Napier Range. This cave is of considerable geomorphological interest (Jennings & Sweeting, 1963b) and contains numerous interesting karst features, including a collapse doline or "karst window" part way along the cave. The cave is essentially a simple stream passage, formed by an underground stream replacing portion of the former superimposed stream occupying the shallow gorge overlying the cave; it is the relic of a longer cave extending upstream and downstream of its present extent (Jennings & Sweeting, 1963b).

The Cave Spring cave systems at the southern end of the Lawford Range include one cave which is over 2 km in surveyed passage length. The entire complex is particularly interesting because it is possibly the only cave in the Limestone Ranges which is developed in the back-reef facies (Nicoll, pers. comm.) and because it includes a series of interesting features in close association with various surface karst forms (Jennings & Sweeting, 1963a). The upstream of the three cave systems, the biggest, consists of a complex ramifying maze of narrow fissure passages intersecting at right angles (Lowry, 1967). This cave is also well decorated with various forms of calcite speleothems.

Old Napier Downs Cave is an interesting cave near the western end of the Napier Range, and quite well decorated with flowstone, stalactites, and stalagmites. It is the outflow of a very large and geomorphologically interesting depression on the plateau behind the wall of the range (Jennings & Sweeting, 1966).

Biology

There is little systematic information on the flora and fauna of the caves of the West Kimberley, but this is more of an indication of lack of research than that the caves are unimportant biologically.

The biology of cave life can be very important scientifically Caves are very specialised environments, and plants and animals which occur there are often correspondingly specialised, exhibiting adaptations which give scientists valuable and often unique insights into evolution, climatic change and ecology.

At least seven species of bats, occur in the caves. These are Macroderma gigas, Eptesicus pumilus, E. douglasi, Miniopterus schreibersii, Taphozous georgianus, Pteropus alecto and Rhinonicterius aurantius (Hamilton-Smith, 1966, pers. comm.). Several of these species are of particular importance, or exhibit bionomic patterns which make environmental protection of importance for their survival. Macroderma gigas is not only a species of great interest, belonging to a monotypic genus which is endemic to Australia (Douglas, 1962, 1967) but has recently been added to the International Union for the Conservation of Nature list of endangered species (I.U.C.N., 1978). The sympatric occurrence of E. pumilus and E. douglasi is at present only known from the region, and is again of interest. The Miniopterus schreibersii of the region belong to the clearly distinguishable sub-species orianae, which is confined to northwestern Australia. The life pattern of this species is such that its survival is dependent upon the availability of appropriate caves to serve as maternity sites. Each population utilises a single such cave, and so it is a potentially vulnerable species. Finally, Rhinonycterius aurantius is one of the least-known bats of Australia, and appears to be relatively rare, again being dependent upon the cave environment for its survival; it is also the only species of its genus, which is endemic to Australia (Hamilton-Smith, pers. comm.).

Thus, although further research is needed to determine the actual distribution of these species and to identify the caves which are of greatest importance to them, the brief notes above should emphasise the need for adequate reservation of cave areas.

Very little is known of the invertebrate fauna. Gray (1973) lists a spider of an undescribed species of the genus Physocyclus from Old Napier Downs Cave. Lowry (1967) mentions wetas (Fam. Rhaphidophoridae) in the upstream cave system of the Cave Spring complex although these are almost certainly crickets of the genus Endacusta (Fam. Gryllidae) which are superficially similar to Rhaphidophorids (Hamilton-Smith, pers. comm.). A small collection made from Old Napier Downs Cave by A. Goede in 1973 included the Physocyclus recorded by Gray, an undetermined Atyid shrimp, the freshwater crab Parathelphusa transversa, Endacusta sp., and the little-known beetle Trox alatus (Fam. Trogidae) (Hamilton-Smith, pers. comm. ).

Although at present it appears that none of the invertebrate fauna of the caves is troglobitic (cave-adapted) in character, this again may be simply due to lack of research. However, the occurrence of Trox alatus does emphasise the possible importance of the caves as an invertebrate habitat. Although this species was described in the mid-nineteenth century from only two specimens of unknown provenance, it was not again collected until Goede's discovery of it in Old Napier Downs Cave and has since been collected from another cave in the Northern Territory.

The flora and microflora of the twilight zone, and of the special localised climatic environment provided at cave entrances, has not yet been studied in the Kimberleys.

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