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Priceless Cultural Importance 40,000 years
This ochre hand stencil in a Nullarbor cave conveys a powerful and poignant story of Mirning Peoples co-existence with Nullarbor Karst Country spanning 40,000 years!
Nullarbor caves preserve some of Australia’s oldest archaeological evidence ~40,000 years associated with stone artefacts (Roberts et al. 1996). Caves were used by Mirning Peoples for shelter, ceremony, and creative expression, as well as a source of water and flint for stone tools.
Additional to caves, there is a multitude of other evidence that record Mirning Peoples links with Nullarbor Country, including rock holes with cap stones, artefact scatters, stone manuports and intriguing stone arrangements.
These all point to the strong and enduring connection that Mirning Peoples had, and which the living descendants of Mirning Peoples continue to have, with Nullarbor Karst Country and connected Sea Country. In South Australia, National Heritage listed Koonalda Cave contains ancient parietal art and other cultural artefacts of immeasurable sacred value.
Tragically in 2022 the ancient art in Koonalda Cave was wantonly desecrated. This crime occurred despite strong warnings made to the South Australian government more than 20 years ago; that Koonalda Cave and its artwork were inadequately protected from vandalism. In Western Australia, Weebubbie, Abrakurrie, and about a dozen other caves are recognised Aboriginal Heritage Places.
However there exist many more caves, rock holes and other cultural heritage sites that are still not formally identified or recognised.
This priceless Australian cultural landscape spanning at least 2,000 generations is existentially threatened and will be irrevocably damaged in one generation if Nullarbor Karst Country is industrialised for hydrogen to be sold overseas.
Nullarbor caves preserve some of Australia’s oldest archaeological evidence ~40,000 years associated with stone artefacts (Roberts et al. 1996). Caves were used by Mirning Peoples for shelter, ceremony, and creative expression, as well as a source of water and flint for stone tools.
Additional to caves, there is a multitude of other evidence that record Mirning Peoples links with Nullarbor Country, including rock holes with cap stones, artefact scatters, stone manuports and intriguing stone arrangements.
These all point to the strong and enduring connection that Mirning Peoples had, and which the living descendants of Mirning Peoples continue to have, with Nullarbor Karst Country and connected Sea Country. In South Australia, National Heritage listed Koonalda Cave contains ancient parietal art and other cultural artefacts of immeasurable sacred value.
Tragically in 2022 the ancient art in Koonalda Cave was wantonly desecrated. This crime occurred despite strong warnings made to the South Australian government more than 20 years ago; that Koonalda Cave and its artwork were inadequately protected from vandalism. In Western Australia, Weebubbie, Abrakurrie, and about a dozen other caves are recognised Aboriginal Heritage Places.
However there exist many more caves, rock holes and other cultural heritage sites that are still not formally identified or recognised.
This priceless Australian cultural landscape spanning at least 2,000 generations is existentially threatened and will be irrevocably damaged in one generation if Nullarbor Karst Country is industrialised for hydrogen to be sold overseas.
Nullarbor karst
The Nullarbor Plain (Latin: nulla feminine of nullus, "no", and arbor, "tree") is part of the area of flat, almost treeless, arid or semi-arid country of southern Australia, located on the Great Australian Bight coast with the Great Victoria Desert to its north.
It is the world's largest single exposure of limestone bedrock, and occupies an area of about 200,000 square kilometres.
At its widest point, the Nullarbor karst stretches ~850 kilometres east - west across the border between South Australia and Western Australia.
There is more to the Nullarbor than the name suggests. Indeed there are trees and an incredible hidden world of caves, of staggering beauty and value.
The Nullarbor remains a kind of wilderness, where it is possible to experience raw and pure nature, profound stillness, immense space with 360-degree uninterrupted horizon views, and the most brilliant starry night skies imaginable.
What is Karst?
Karst landscapes and karst features are formed by the dissolutional weathering of soluble carbonate rocks such as limestone, dolomite, and gypsum.
Karst landscapes are often characterised by well developed subterranean drainage systems with caves, dolines, sinking streams and springs.
Dolines, also known as ‘sinkholes,’ are enclosed depressions formed by limestone solution or collapse - they indicate the presence of underground drainage and cave systems.
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This massive doline on the Nullarbor Plain is 80m in diameter and 40m deep! It was formed by collapse of the limestone into an enormous, flooded cave conduit in the aquifer which lies about 80m below the surface.
The existence of this ancient cave drainage system, which contains the largest natural cavern in Australia, is indicated by the line of shallow dolines extending 1.5 km towards the next major collapse doline, and from there a further 25 km to discharge into the Southern Ocean at the Great Australian Bight.
This cave system lies immediately adjacent to a massive wind and solar industrialisation proposal that threatens to despoil its wild and natural beauty.
Ancient caves millions of years old
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This typical large Nullarbor cave passage has been formed by gradual upwards collapse of the roof over millions of years.
Deeper beneath the rock-strewn floor lies the aquifer and a large waterfilled conduit which has been gradually dissolving the soluble carbonate limestone and carrying it away in solution, thus enabling the cave to grow larger over time.
Nullarbor caves are ancient, some may have been forming for tens of millions of years, and they are still evolving.
The domed roof in this photograph traps warm humid air which creates an ideal roost site for a population of cave dwelling bats, while rock ledges and hollows in the walls of the entrance doline are perfect nesting and roosting sites for Welcome Swallows and other birds including kestrels and owls.
On the Nullarbor, where trees are scarce or absent, the caves and dolines are critical roosting, nesting and breeding habitat for many birds and bats.
Nullarbor karst Country & sea Country are connected
Beneath the surface of the Nullarbor there is an immense limestone aquifer and enormous submerged caverns with crystal-clear groundwater.
From the northern margin of the limestone plateau ~200 to ~300 km inland, the aquifer carries groundwater all the way to the coastline where it discharges into the ocean in the Great Australian Bight.
The Nullarbor limestones, aquifer, caves, and the Southern Ocean are inseparably connected in space and time.
Sea level fluctuations over the past ~40 million years deposited the limestones initially and then subsequently controlled water table levels in the aquifer, which in turn, controlled cave formation.
As sea levels have risen and fallen over millenia so too, in unison, has the water table in the aquifer risen and fallen.
The karst aquifer and the ocean are connected.
The limestone platform extends beneath the ocean into the Great Australian Bight and during the repeated glacial cycles of the Pleistocene spanning the last 2.58 million years sea levels have risen and fallen, alternately exposing, and submerging the platform as far as the edge of the continental shelf.
During the Last Glacial Maximum around 20,000 years ago, sea levels were about 110 metres lower than present, and the coastline was up to 300 kilometres further south!
The First Peoples walked, hunted, and gathered on this coastal plain.
Yerkala Mirning People retain a strong connection to Sea-Country and one of their Stories (https://whaledreaming.au) says:
“Yetarngarin, the continental shelf is the place where our ancestors lived, where they walked on what is now the seabed and practiced ceremony at our sacred ochre site below the waves.”
Rock Holes
Rock holes, like blowholes, are a quientessential Nullarbor karst feature .
This rockhole was formed by rainfall runoff concentrating at the lowest point in this small basin and gradually dissolving the hard limestone to form this circular hole about 500 mm deep which can hold water for days, weeks, and even months after rainfall.
There are thousands of small rock holes on the surface of the Nullarbor karst.
Many of these rock holes / wilpanabie have extremely high cultural importance as navigation way points for the First Peoples, and a critical source of water in this arid and otherwise waterless Country.
Testimony to their usage as a water source is the perfectly fitting capstone placed alongside, and over, the rock hole to protect the water resource.
The integrity of hundreds, if not thousands, of rock holes / wilpanabie and other sensitive karst features and cultural heritage sites, many still not formally identified or protected, will be compromised, and threatened if the Nullarbor is transformed into an enormous 15,000 square kilometre industrial wind and solar farm to produce hydrogen / ammonia for export overseas.
This rockhole was formed by rainfall runoff concentrating at the lowest point in this small basin and gradually dissolving the hard limestone to form this circular hole about 500 mm deep which can hold water for days, weeks, and even months after rainfall.
There are thousands of small rock holes on the surface of the Nullarbor karst.
Many of these rock holes / wilpanabie have extremely high cultural importance as navigation way points for the First Peoples, and a critical source of water in this arid and otherwise waterless Country.
Testimony to their usage as a water source is the perfectly fitting capstone placed alongside, and over, the rock hole to protect the water resource.
The integrity of hundreds, if not thousands, of rock holes / wilpanabie and other sensitive karst features and cultural heritage sites, many still not formally identified or protected, will be compromised, and threatened if the Nullarbor is transformed into an enormous 15,000 square kilometre industrial wind and solar farm to produce hydrogen / ammonia for export overseas.
Blowholes
The famous Nullarbor blowholes are so-called because they exhale, and inhale, immense volumes of air in response to atmospheric pressure changes, with roaring winds up to 70 km/hr.
Blowholes are typically less than 2m in diameter and 2m to 20m deep, however the strong air currents indicate that they connect to extensive cave systems including a remarkable network of anastomosing tubes or meso-caverns (see next section).
There are thousands of blowholes scattered across the entire Nullarbor.
A key point to understand is that the entire ~200,000 km2 limestone platform is a single hydrogeological entity united by its geology and aquifer, and that within this enormous karst region there exists a multitude of subterranean drainage systems, both active and ancient, that are contiguous, and interconnected to greater or lesser degrees.
Management and conservation of this karst, and its features requires a holistic approach at the scale of the entire landscape / biogeographic region, and the natural processes which act upon it.
The protection of individual karst landforms, especially caves, cannot be achieved in isolation from the surrounding landscape and the broader hydrogeological systems in which they are developed.
Blowholes are typically less than 2m in diameter and 2m to 20m deep, however the strong air currents indicate that they connect to extensive cave systems including a remarkable network of anastomosing tubes or meso-caverns (see next section).
There are thousands of blowholes scattered across the entire Nullarbor.
A key point to understand is that the entire ~200,000 km2 limestone platform is a single hydrogeological entity united by its geology and aquifer, and that within this enormous karst region there exists a multitude of subterranean drainage systems, both active and ancient, that are contiguous, and interconnected to greater or lesser degrees.
Management and conservation of this karst, and its features requires a holistic approach at the scale of the entire landscape / biogeographic region, and the natural processes which act upon it.
The protection of individual karst landforms, especially caves, cannot be achieved in isolation from the surrounding landscape and the broader hydrogeological systems in which they are developed.
Vulnerable Aquifer & World Class Underwater Caves
For more than 50 years cave divers have been exploring and mapping the stunningly beautiful and internationally famous underwater caves of the Nullarbor.
This photo shows two divers in the aptly named Railway Tunnel, which is the continuation of the tunnel from the cave lake photo featured above.
This large natural tunnel has been explored by cave divers for 400 metres distance and 40 metres water depth to a point where further exploration is blocked by boulders however the cave system continues beyond, carrying ancient groundwater to the Southern Ocean and the Great Australian Bight.
The ancient groundwater which sustains the Nullarbor limestone aquifer, and which feeds this cave, commenced its journey as rainfall soaking underground into the limestone up to 200 kilometres inland from the Great Australian Bight.
The Nullarbor aquifer and caves are the habitat of extraordinary life forms including stygofauna and rare microbial communities, which occur nowehere else on Earth.
The Nullarbor aquifer and its unique life forms are highly vulnerable to contamination.
Tragically, the stunningly beautiful cave system in this photograph, and others like it, are directly in the path of a mega-scale hydrogen / ammonia industrialization project that proposes to smother 22,000 square kilometres of fragile Nullarbor Karst Country in 3,000 wind turbines, 60 million solar panels, powerlines, pipelines, roads, and associated infrastructure.
The industrialisation proposal includes an ammonia plant and storage facility, workshops, and a township for ~8,000 people, situated near Eucla and within a few kilometres of this globally significant cave system!
Nullarbor Karst Country is NOT suitable for industrialisation!
Microbial Mantles - Life, Universe & The Nullarbor
The cave lakes and underwater tunnels on the Nullarbor support rare and unique extremophile organisms known as microbial mantles, a highly unusual and specialized community of primitive bacteria and archaea (=ancient group similar to bacteria but different).
These soft gelatinous tentacles in Weebubbie Cave, up to one meter long, are extremely fragile and vulnerable to any kind of disturbance or groundwater contamination.
They are of great scientific interest and importance because unlike most other ecosystems on earth which ultimately obtain their energy from plants via carbon photosynthesis, these organisms appear to obtain their energy by metabolising chemicals obtained from the surrounding limestone or groundwater.
Similar types of organisms are found in volcanic hot springs and deep ocean vents; however, the Nullarbor community represents a distinctive microbial ecosystem, in which primary productivity is due to the combined activity of archaeal ammonia-oxidisers and bacterial nitrite oxidisers (Source: Tetu, S.G. et al, The ISME Journal (2013) 7, 1227–1236; doi:10.1038/ismej.2013.14).
Astrobiology is the study of life in the universe. In seeking to understand the possibility of life beyond Earth, astrobiologists study how life originates and how it can survive in extreme environments on Earth, and, which might be like environments found on other planets.
If evidence of life, or past life, is ever found on Mars, or other planets, it may well be found in groundwater.
Weebubbie Cave and its unique groundwater community of microbial extremophiles, along with many other Nullarbor caves, are under threat from an enormous, proposed hydrogen industrialisation project which includes an ammonia production plant and storage facility, workshops, and proposed township with thousands of workers, all located within a few kilometres of these fragile world heritage quality cave ecosystems!
Please help Save Life Under The Nullarbor by signing and sharing the Petition.
Dolines are Ecological Islands in Ocean of Aridity
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The flat arid surface of the Nullarbor plain is very exposed to the elements and there is extremely limited shelter for animals and moisture-loving plants.
Much of the inland parts of the Nullarbor karst are treeless and dominated by a low open chenopod shrubland of bluebush and saltbush.
There are very places for mammals and birds to find shade, shelter, water, roost, or nest sites, except where there are karst features such as dolines, caves, blowholes, rock holes, limestone pavements, and pocket valleys. Karst pavements collect and channel runoff into shallow solution pans and rock holes which may hold water for days, weeks, and even months in this otherwise waterless landcape. Kangaroos, emus, and other animals and birds know this, and after a rainfall event they congegate at these ephemeral water sources. In this harsh arid country, this is a memorable sight to behold.
The deeper dolines and cave entrances maintain a moist sheltered micro-climate that allows the growth of more mesic plants that cannot survive on the surface, such as the creeping native herb, Galium leptogonium, which is listed as a Priority 3 Flora species.
Doline micro-environments and their vegetation, in turn, support many invertebrates such as moisture-dependent snails, and reptiles such as geckos. At night, especially after rain, the dolines come alive with small animals that otherwise remain hidden and not seen.
Caves are critical roosting and breeding sites for two species of bats, the Chocolate wattled bat Chalinolobus morio, and the Lesser long-eared bat, Nyctophilus geoffroyi. Closer to the escarpment and coast the region receives more rainfall, and there is mallee eucalypt and myall woodlands. Even in this woodland country, karst features provide essential shelter, and water, for many birds, mammals, and reptiles. Pocket valleys are another important karst feature found along the Hampton and Wylie escarpments. These valleys receive and concentrate sporadic rainfall runoff and provide shade and shelter for birds and animals in cliff hollows, under overhangs, and trees.
Nullarbor karst features function as ecological island refugia in an ocean of environmental adversity. They deserve to be respected and protected. The proposal to install 3,000 wind turbines across 22,000 square kilometres of the Nullarbor would put birds and bats at risk.
Much of the inland parts of the Nullarbor karst are treeless and dominated by a low open chenopod shrubland of bluebush and saltbush.
There are very places for mammals and birds to find shade, shelter, water, roost, or nest sites, except where there are karst features such as dolines, caves, blowholes, rock holes, limestone pavements, and pocket valleys. Karst pavements collect and channel runoff into shallow solution pans and rock holes which may hold water for days, weeks, and even months in this otherwise waterless landcape. Kangaroos, emus, and other animals and birds know this, and after a rainfall event they congegate at these ephemeral water sources. In this harsh arid country, this is a memorable sight to behold.
The deeper dolines and cave entrances maintain a moist sheltered micro-climate that allows the growth of more mesic plants that cannot survive on the surface, such as the creeping native herb, Galium leptogonium, which is listed as a Priority 3 Flora species.
Doline micro-environments and their vegetation, in turn, support many invertebrates such as moisture-dependent snails, and reptiles such as geckos. At night, especially after rain, the dolines come alive with small animals that otherwise remain hidden and not seen.
Caves are critical roosting and breeding sites for two species of bats, the Chocolate wattled bat Chalinolobus morio, and the Lesser long-eared bat, Nyctophilus geoffroyi. Closer to the escarpment and coast the region receives more rainfall, and there is mallee eucalypt and myall woodlands. Even in this woodland country, karst features provide essential shelter, and water, for many birds, mammals, and reptiles. Pocket valleys are another important karst feature found along the Hampton and Wylie escarpments. These valleys receive and concentrate sporadic rainfall runoff and provide shade and shelter for birds and animals in cliff hollows, under overhangs, and trees.
Nullarbor karst features function as ecological island refugia in an ocean of environmental adversity. They deserve to be respected and protected. The proposal to install 3,000 wind turbines across 22,000 square kilometres of the Nullarbor would put birds and bats at risk.
Caves are the Books in the Library of the History of the World
Like libraries and museums, the Nullarbor caves and blowholes contain priceless treasures of immeasurable scientific and cultural importance.
In 2002 speleologists made Australia’s palaeontological find of the century with the first complete skeleton of the famous extinct ‘marsupial lion’ Thylacoleo carnifax.
The articulated skeleton lay undisturbed since the day it died after falling into a Nullarbor cave sometime between 400,000 and 800,000 years ago.
This skeleton along with the bones of 68 other species of mammals, birds, and reptiles, provided a trove of information about the mid-Pleistocene, a crucial missing time-slice in Australia’s palaeontological record.
Professor Jon Woodhead, University of Melbourne, said:
“In Australia, however, only two regions – the Naracoorte caves of South Australia and the now collapsed caves of Riversleigh in Northern Australia – have attained World heritage listing, based in both cases, on their outstanding mammal fossils.”
“Despite their unique attributes, the caves of the Nullarbor have, unfortunately not yet received such accolades.”
(Source: https://pursuit.unimelb.edu.au/articles/it-s-time-the-nullarbor-caves-had-world-heritage-status)
Sadly, the heartland of the Nullarbor karst, including the area where these incredibly significant bone discoveries were made, is threatened by an enormous hydrogen industrialisation project.
The Western Green Energy Hub proposes to smother 22,000 square kilometres of the Nullarbor heartland in 3,000 wind turbines, 60 million solar panels, and vast infrastructure network.
In the proposed industrial footprint, there are hundreds of caves and thousands of blowholes, and doubtless many more remain to be discovered!
Each and any of these caves and blowholes may contain a library and museum of immeasurable scientific and cultural importance!
The proposed Western Green Energy Hub is utterly incompatible with the World Heritage significant Nullarbor karst.
In 2002 speleologists made Australia’s palaeontological find of the century with the first complete skeleton of the famous extinct ‘marsupial lion’ Thylacoleo carnifax.
The articulated skeleton lay undisturbed since the day it died after falling into a Nullarbor cave sometime between 400,000 and 800,000 years ago.
This skeleton along with the bones of 68 other species of mammals, birds, and reptiles, provided a trove of information about the mid-Pleistocene, a crucial missing time-slice in Australia’s palaeontological record.
Professor Jon Woodhead, University of Melbourne, said:
“In Australia, however, only two regions – the Naracoorte caves of South Australia and the now collapsed caves of Riversleigh in Northern Australia – have attained World heritage listing, based in both cases, on their outstanding mammal fossils.”
“Despite their unique attributes, the caves of the Nullarbor have, unfortunately not yet received such accolades.”
(Source: https://pursuit.unimelb.edu.au/articles/it-s-time-the-nullarbor-caves-had-world-heritage-status)
Sadly, the heartland of the Nullarbor karst, including the area where these incredibly significant bone discoveries were made, is threatened by an enormous hydrogen industrialisation project.
The Western Green Energy Hub proposes to smother 22,000 square kilometres of the Nullarbor heartland in 3,000 wind turbines, 60 million solar panels, and vast infrastructure network.
In the proposed industrial footprint, there are hundreds of caves and thousands of blowholes, and doubtless many more remain to be discovered!
Each and any of these caves and blowholes may contain a library and museum of immeasurable scientific and cultural importance!
The proposed Western Green Energy Hub is utterly incompatible with the World Heritage significant Nullarbor karst.
Nullarbor Troglofauna & the Great Divide between West and East
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More than 280 species of invertebrate animals have been recorded from Nullarbor caves and groundwater.
Of particular interest are 30 species which cannot survive on the surface and have become specially adapted to subterranean life – they have reduced eyes and pigment and elongated appendages; some species have lost their eyes entirely.
Nullarbor troglobites are geographic relics that have survived the progressive aridification of surface environments on the Nullarbor by colonising humid underground habitats and adapting to life in complete darkness.
As Australia gradually dried-out over millions of years the surface of the Nullarbor became inhospitable and a barrier to dispersal for many species. The eyed surface-dwelling ancestors of the troglobites either migrated elsewhere or became extinct with the spreading of aridity.
Several Nullarbor troglobites have distant relatives still living in moist surface and cave habitats in the cooler and wetter southeastern and southwestern corners of the continent. The cave spider genus Tartarus is a good example, with its sister genus Baiami found in forests and caves of southwest and southeast Australia.
The arid Nullarbor karst is thus a great biogeographic divide, separating the fauna and flora of eastern and western Australia.
It is internationally recognised by scientists as the 'Nullarbor Ecoregion of the World'.
It has contributed to the evolution of Australia’s remarkable biodiversity, including for example, the extraordinarily rich flora in the southwest corner of the continent.
And the Nullarbor karst harbours a living treasure trove of subterranean biodiversity which can tell an important and fascinating story about Australia’s biogeographic and evolutionary history.
Much of this story is waiting to be unravelled by scientists, and there is no doubt that Nullarbor caves harbour many new species unknown to science, and yet to be discovered!
Hotspots of Subterranean Biodiversity
Nullarbor caves are hotspots of biodiversity, with some caves harbouring ten species of troglobites and stygobites, and others with more than 40 invertebrate species overall.
Very few caves have been sampled on a systematic basis, and a cave fauna survey of the entire karst region is urgently needed in view of the looming threats from industrialisation and mining.
Nullarbor troglobites are notable for several large and spectacular species that are highly cave-adapted and belong to genera that are endemic to the Nullarbor karst.
The largest, rarest, and most unusual troglobite is a mygalomorph spider, Troglodiplura (photo above by Paul Devine). This spider is of considerable scientific interest because it is the only known troglobitic mygalomorph in Australia and one of only 14 or so cave-adated mygalomorphs worldwide. Troglodiplura includes at least four described species with additional undescribed species known. Troglodiplura is the Australian Cave Animal of the Year 2024 – for more information: https://www.caveanimaloftheyear.org.au/
A second iconic Nullarbor cave spider, Tartarus, includes four described species, and spins a beautiful and extremely fragile web (photo above).
Another large and iconic Nullarbor troglobite is the blind cockroach, Trogloblattella nullarborensis (photo in section above), which manages to survive even in the most remote and energy-poor parts of caves. This unusually docile and slow-moving cockroach is completely blind and shows no reaction to light.
Other troglobites include pseudoscorpions, planthoppers, centipedes - Cryptops (photo under), and isopods - Buddelundia eberhardi (photo under).
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Cave Rights for Troglobites
Some Nullarbor troglobites are extremely rare and known from only one or two caves and very few specimens, such as the carabid beetles, Speothalpius grayi and Speozuphium poulteri (photo above).
The Pannikin Plain Cave Isopod, Abebaioscia troglodytes is listed as rare and vulnerable in Western Australia.
While there are exceptions, many troglobites and stygobites are short-range endemic (SRE) species and therefore more vulnerable to threats and extinction from human activities and environmental changes. On this basis a high conservation importance may be attributed to troglobites and stygobites.
While there are exceptions, many troglobites and stygobites are short-range endemic (SRE) species and therefore more vulnerable to threats and extinction from human activities and environmental changes. On this basis a high conservation importance may be attributed to troglobites and stygobites.
Nullarbor Stygofauna
The Nullarbor karst harbours a rich and endemic fauna of remarkable cave-adapted invertebrates; aquatic stygofauna and terrestrial troglofauna including crustaceans, blind spiders, beetles, centipedes, and cockroaches.
This blind Nullarbor amphipod, Nurina poulteri, is found only in groundwater of the Nullarbor karst.
Its marine ancestors lived in the Southern Ocean and may have colonised caves and groundwater of the Roe Plains during a Pliocene marine incursion ~3 to 5 million years ago.
This marine incursion cut the plain which is up to 40 km wide and nearly 300 km in length between Wilson Bluff and Twilight Cove.
The ancient shoreline is now the base of the Hampton Escarpment, which the Eyre Highway runs alongside between Eucla and Madura Pass.
The Roe Plains are geologically and hydrologically an integral part of the Nullarbor karst. The aquifer under the Nullarbor high plains (~ 90m above sea level at the escarpment) is the same aquifer under the low-level Roe Plains (< 40m asl) and this groundwater system ultimately drains into the Southern Ocean.
During the marine incursion which formed the Roe Plains and the Hampton Escarpment a thin layer of calcarenite limestone was deposited on the seabed.
The Roe calcarenite is only a few metres thick and is richly fossiliferous with many different types of molluscs, echinoderms, corals, brachiopods, bryozoans, foraminifers, annelids, arthropods, calcareous algae, and occasional fish.
By studying these fossils scientists from the Western Australian Museum were able to estimate the age of the calcarenite, the marine incursion and the formation of the Hampton Escarpment.
They could also deduce that the ocean environment at the time was a slightly warmer, shallow, inshore continental shelf, with a sandy bottom and rich growth of sea grasses and other marine vegetation. Source: Kendrick, McNamara, Brimmell (1997).
What are Anastomosing Tubes or Meso-caverns?
Anastomosing tubes, or meso-caverns, are a type of ‘proto-cave’ or miniature cave, typically ranging from ~5mm to 500mm diameter which honeycomb the Nullarbor limestones.
They are formed by water dissolving the rock, typically along a joint or bedding plane, as exposed here in a cave wall where a limestone block has fallen away to reveal the tubes. These tubes are ~5mm to 20mm in diameter.
The mesocavernous network is ubiquitous beneath the entire karst plain – it can be seen wherever the limestone undersurface is exposed in dolines, caves, quarries, road cuttings and even boulders lying on the ground.
It is of immense consequence and importance to understanding the extraordinary hydrogeological porosity and functional dynamics of the Nullarbor karst.
The mesocavernous network is interconnected with the larger caves and blowholes, and this network is what causes the famous Nullarbor blowholes to blow.
From little things big things grow
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Large caves grow from small caves.
Beneath a thin layer of caprock ~1m to 2m thick the Nullarbor limestone is honeycombed by a highly interconnected network of anastomosing tubes, or mesocaverns, ranging from ~5 mm to 500 mm in diameter.
The honeycombed rocky overhangs in Nullarbor dolines are critical roosting and nesting habitat for many birds including swallows, kestrels, and owls.
Anastomosing tubes, or meso-caverns, are a type of ‘proto-cave’ or miniature cave, too small for people to enter but large enough for air, water, tree roots and invertebrates to pass through.
Over time some anastomising tubes grow larger than their neighbours as groundwater takes the flow paths of least hydraulic resistance and preferentially enlarges some tubes over others, eventually leading to the formation of a single large main conduit.
From little things big things grow!
Big Thing!
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This Nullarbor doline is 60m x 30m across, formed by collapse of the limestone into an enormous underlying cave system and aquifer lying ~90 metres below the surface. At the bottom of the frame a person can be seen abseiling into the cave on a rope.
This highly significant doline and cave lies within a few kilometres of a proposed ammonia plant and storage facility, workshops, and a new township for thousands of workers - part of a mega-scale hydrogen industrialisation project that threatens this cave system and many other Nullarbor caves with world heritage values.
Soils ain't soils
The critical importance of soils is often overlooked and yet they are a fundamental component in most terrestrial ecosystems.
Soils filter and store water, nutrients, and pollutants.
Soils anchor plants roots, sequester carbon, and provide habitat for invertebrates and microorganisms which perform keystone ecological roles and processes such as decomposition and nitrogen-fixation.
Healthy soil is a dynamic living ecosystem. Soils grow food for humans and herbivores. Around the world, many soils are seriously degraded or have been lost entirely due to lack of care.
Without soils life on Earth would be very difficult!
On the Nullarbor, the shallow skeletal limestone soils and their thin cryptogam crust of lichens, mosses, liverworts, fungi, and blue-green algae, vital for maintaining soil stability, are extremely fragile and highly prone to any form of ground disturbance.
The cryptogam crust (see photo) is so fragile that wherever animals or humans walk repeatedly across the same patch of ground the crust is broken or destroyed.
When the cryptogam crust is broken or destroyed, the very fine-grained clay soils become highly prone to erosion by wind and water.
The crust is always damaged when vehicles are driven on it, even just once, leaving a highly visible scar on the landscape which takes years to recover.
Crust which is driven on repeatedly is destroyed and does not recover due to soil compaction, creating a permanent scar on the landscape.
After rain vehicle tracks become extremely slippery and boggy because the Nullarbor soils are rich in clay.
Driving on tracks when they are wet quickly results in ever- deepening bog holes and ever-widening tracks as more tracks are made to avoid bog holes.
A single track soon becomes a criss-crossing mess of multiple damaged tracks, tens of metres across.
After rain, this limestone country cannot be driven on without high likelihood of causing serious damage to the track and adjacent vegetation.
After rainfall the tracks become drainage channels and eroded sediment may be carried underground and plug cave systems.
Attempts have been made to rehabilitate excessive tracks by soil ripping however this creates another kind of impact as the kunkar (calcrete) layer underlying the thin skeletal soils is broken up and lifted to the surface, resulting in lumpy, bleached stoney ground which does not restore the ground to its pre-disturbance condition.
The best way to minimise damage and erosion to fragile Nullarbor soils is to stay on existing tracks, do not create new tracks, and avoid driving on tracks when they are slippery and boggy after rain.
Responsible Pastoralism, Land Conservation & World Heritage Listing can co-exist
Broad-acre sheep and cattle farming have wrought some changes to vegetation and soil over the decades, and, in common with the rest of continental Australia, numerous species and populations of small native mammals were decimated by the earlier introduction of foxes, cats, and rabbits.
Despite these changes, the internationally recognised Nullarbor Eco-region of the World retains much of its natural biogeographic intactness.
In assessing the world heritage significance of the Nullarbor karst, the 1992 report (Davey et al.) stated emphatically that while some resource degradation has occurred in the past, responsible pastoral use and conservation management can co-exist. Indeed, there are existing Australian precedents where other world heritage areas include pastoral activity.
Ironically on the Nullarbor, the caves situated within national parks and reserves (as well as the caves in so-called “vacant” crown land) have suffered the most visitation and consequently the most degradation.
This is due to the region’s remoteness and absence of on-ground ranger presence.
Signs, gates, and fences have proved completely ineffective at protecting the caves, which have been repeatedly entered, damaged, and vandalised over the decades.
As recently as 2022, ancient aboriginal etchings in Koonalda Cave, located inside the Nullarbor National Park, were irreparably desecrated!
In stark contrast, the caves inside pastoral leases are less visited and much better protected.
This is because many of the would-be casual visitors and vandals are deterred by the need to seek permission for access to private leasehold property, which may also be declined by the lease holder.
Even without formal reservation proclamation, there is great potential for further fostering of karst and cave conservation initiatives between pastoralists, traditional custodians, and land management agencies.