Granite outcrops of Western Australia are weathered landforms that occur throughout the state of

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

, composed primarily of the rock type

granite Granite () is a coarse-grained ( phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies under ...

. All recognised types of this landform can be observed, commonly as

bornhardt A bornhardt () is a dome-shaped, steep-sided, bald rock outcropping at least in height and several hundred metres in width. They are named after Wilhelm Bornhardt (1864–1946), a German geologist and explorer of German East Africa, who first d ...

s, but also as

inselberg An inselberg or monadnock () is an isolated rock hill, knob, ridge, or small mountain that rises abruptly from a gently sloping or virtually level surrounding plain. In Southern Africa a similar formation of granite is known as a koppie, a ...

s, castle koppies and nubbins. Rising abruptly from the surrounding landscape they create a variety of

microhabitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s for plants, and provide seasonal resources and refuge for a range of animals. These areas thus have rich

biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') l ...

and many

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

. They are significant locations that tie in with the Aboriginal and European cultural heritage of

Ecology

Granite outcrops in the state are ecologically complex and insular, often providing niches for ancient lineages of organisms that are relics of a wetter climate. These niches include unfractured rock surface that is covered in

biofilm A biofilm comprises any syntrophic consortium of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular ...

, composed of cyanobacteria that give massive rockfaces a characteristic colour. Crusts of lichens also appear, visible mats constructed by blue-green alga and fungal associations that may be up to a billion years old. Mats composed primarily of moss and spike-moss are also found when adequate moisture is available, which in turns provides opportunities for other organisms. At least 1300 plant species occur on granite outcrops in Western Australia, many of which are endemic to these sites. Some of these plant species gain a purchase a clefts and fissures in the rock face, and trees or large shrubs may appear in a bonsai-form. Slabs of rock, split by exfoliation or cracked and pushed up to an A profile, form habitat that is cooler, damper, and secure for plant and animal species that are often specially adapted to the narrow environ. Pools of rainwater known as

gnamma A panhole is a depression or basin eroded into flat or gently sloping cohesive rock.Twidale, C.R., and Bourne, J.A., 2018''Rock basins (gnammas) revisited. ''Géomorphologie: Relief, Processus, Environnement, Articles sous presse, Varia, mis en l ...

s often form on granite outcrops. These provide habitat to around 230 aquatic

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s, of which at least 50 are endemic to these pools, and provide fresh water to other inhabitants and visitors. The flora of these granitic outcrops is notable in many regards. Woody species may include tall trees, eucalypts, sheoak, acacia, and rock figs of the genus ''

Ficus ''Ficus'' ( or ) is a genus of about 850 species of woody trees, shrubs, vines, epiphytes and hemiepiphytes in the family Moraceae. Collectively known as fig trees or figs, they are native throughout the tropics with a few species extendi ...

'', smaller species include these genera and taxa of verticordia,

banksia ''Banksia'' is a genus of around 170 species in the plant family Proteaceae. These Australian wildflowers and popular garden plants are easily recognised by their characteristic flower spikes, and fruiting "cones" and heads. ''Banksias'' range ...

grevillea ''Grevillea'', commonly known as spider flowers, is a genus of about 360 species of evergreen flowering plants in the family Proteaceae. Plants in the genus ''Grevillea'' are shrubs, rarely trees, with the leaves arranged alternately along the b ...

, and melaleuca. The number of orchid species occurring on them is 141, and 16% of these are endemic to these landforms. Those orchid species endemic to outcrops may be widely distributed or, as with '' Spiculaea ciliata'', only found at locations separated by a few kilometres. Human use of the outcrops has been well documented, and as a resource—for food and especially permanent water—they were often crucial to existence. More recent material also provides useful information as to how to manage the environment of the rocks and their surroundings. Studies and conferences have also explored the natural history. A number of animals are restricted to granite outcrops, including four species of reptile, the

mygalomorph The Mygalomorphae, or mygalomorphs, are an infraorder of spiders, and comprise one of three major groups of living spiders with over 3000 species, found on all continents except Antarctica. Many members are known as trapdoor spiders due to t ...

spider Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...

''Teyl luculentus'', and the

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e of the

chironomid The Chironomidae (informally known as chironomids, nonbiting midges, or lake flies) comprise a family of nematoceran flies with a global distribution. They are closely related to the Ceratopogonidae, Simuliidae, and Thaumaleidae. Many specie ...

fly ''Archaeochlus''. They are also an important habitat of rock-wallabies such as the black-flanked rock-wallaby, and '' Ctenophorus ornatus'', the ornate crevice-dragon. Granitic outcrops also provide refuge for animals, as temporary protection against predation or seasonal habitat insulated from the extremes of weather.

Great Southern region

Granite outcrops occur along the southern coast of the state, where they are exposed to high winds and extremes and wave and tidal action. They often form steep coastline, headlands and islands. * The granitic forms at the coast of Torndirrup National Park * Gibraltar Rock * Castle Rock and Balancing Rock at

Porongurup National Park Porongurup National Park is a national park in the Great Southern region of Western Australia. It covers , and is southeast of Perth and north of Albany. The park contains the Porongurup Range, which is the relic core of an ancient mount ...

* The granitic forms at Two Peoples Bay * The granitic forms at Waychinicup National Park, Mount Manypeaks and Cheynes Beach. * Elephant Rocks, granite boulders that make up

Greens Pool Greens Pool is a sandy white beach with boulders on the south coast of Western Australia between Denmark and Walpole. This sheltered area is part of William Bay National Park and has a sandy white beach ringed by large granite boulders that pre ...

and other forms at William Bay National Park * The granitic forms around Mount Melville and

Mount Clarence Mount is often used as part of the name of specific mountains, e.g. Mount Everest. Mount or Mounts may also refer to: Places * Mount, Cornwall, a village in Warleggan parish, England * Mount, Perranzabuloe, a hamlet in Perranzabuloe parish, C ...

in Albany

Wheatbelt region

* Baladjie Rock * Beringbooding Rock * Boyagin Rock * Bruce Rock * Corrigin Rock * Datjoin Rock * Eaglestone Hill *

Elachbutting Rock Elachbutting Rock is a granite rock formation located approximately east of Bonnie Rock and approximately north east of Mukinbudin in the eastern Wheatbelt region of Western Australia. The rock is situated within Elachbutting Rock Nature Res ...

Elachbutting Rock
/ref> * Gorge Rock * Hunts Soak * Jilakin Rock * King Rock *

Kokerbin Rock Kokerbin Rock, also known as Kokerbin Hill, is a granite rock formation located within Kokerbin Nature Reserve in the Wheatbelt region of Western Australia. The area has special significance for the Nyoongar. There are claims that Kokerbin Rock ...

also known as Kokerbin Hill ** Wave Wall, Dog Rock, Devils Marbles * Mount Walker ** Anderson Reserve, Twine Reserve and Roe Dam *

Puntapin Rock Puntapin Rock is a granite rock formation located approximately south east of Wagin, Western Australia, Wagin and approximately west of Dumbleyung, Western Australia, Dumbleyung in the western Wheatbelt (Western Australia), Wheatbelt region ...

* Sandford Rocks *

The Humps The Humps is a granite rock formation known as a "stepped bornhardt inselberg". It is located within The Humps Nature Reserve approximately east of Perth and north east of Hyden in the eastern wheatbelt region of Western Australia. Risin ...

* Wave Rock * Westonia Common ** Boodalim Soak * Yeerakine Rock * Yilliminning Rock east of Narrogin * Yorkrakine Rock

Notes and references

* Bayly, I.A.E. ''Rock of ages : human use and natural history of Australian granites'' Nedlands, W.A.: Tuart House, 1999. * ''Granite Outcrops Symposium, 14–15 September 1996''. pp. 87–237. ''Journal of the Royal Society of Western Australia.'' vol.80, pt.3 (September 1997) *

External links

Granite Outcrops in the Wheatbelt
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Ecology

Great Southern region

Wheatbelt region

See also

Notes and references

External links