The Pinnacles are

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

formations within

Nambung National Park Nambung National Park is a national park in the Wheatbelt (Western Australia), Wheatbelt region of Western Australia, northwest of the state capital Perth, and south of the small coastal town of Cervantes, Western Australia, Cervantes. The park ...

, near the town of

Cervantes, Western Australia Cervantes is a town in Western Australia located about north-north-west of the state capital, Perth, in the Shire of Dandaragan local government area. At the 2016 census, Cervantes had a population of 527. The town was named after a ship tha ...

Features

The area contains thousands of weathered

pillars. Some of the tallest

pinnacles A pinnacle is an architectural element originally forming the cap or crown of a buttress or small turret, but afterwards used on parapets at the corners of towers and in many other situations. The pinnacle looks like a small spire. It was mainly ...

reach heights of up to above the yellow sand base. The different types of formations include ones which are much taller than they are wide and resemble columnssuggesting the name of Pinnacleswhile others are only or so in height and width resembling short tombstones. A

cross-bedding In geology, cross-bedding, also known as cross-stratification, is layering within a stratum and at an angle to the main bedding plane. The sedimentary structures which result are roughly horizontal units composed of inclined layers. The origina ...

structure A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ...

can be observed in many pinnacles where the angle of deposited sand changed suddenly due to changes in prevailing winds during formation of the limestone beds. Pinnacles with tops similar to mushrooms are created when the

calcrete Caliche () is a soil accumulation of soluble calcium carbonate at depth, where it precipitates and binds other materials—such as gravel, sand, clay, and silt. It occurs worldwide, in aridisol and mollisol soil orders—generally in arid or s ...

capping is harder than the limestone layer below it. The relatively softer lower layers weather and erode at a faster rate than the top layer leaving behind more material at the top of the pinnacle.

Formation

The raw material for the limestone of the Pinnacles came from

seashell A seashell or sea shell, also known simply as a shell, is a hard, protective outer layer usually created by an animal or organism that lives in the sea. Most seashells are made by Mollusca, mollusks, such as snails, clams, and oysters ...

s in an earlier era that was rich in

marine life Marine life, sea life or ocean life is the collective ecological communities that encompass all aquatic animals, aquatic plant, plants, algae, marine fungi, fungi, marine protists, protists, single-celled marine microorganisms, microorganisms ...

. These shells were broken down into lime-rich

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

s that were blown inland to form high mobile

dune A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat ...

s.Lipar, M., Webb, J.A., 2015. The formation of the pinnacle karst in Pleistocene aeolian calcarenites (Tamala Limestone) in southwestern Australia. Earth-Science Reviews 140, pp. 182-202 However, the manner in which such raw materials formed the Pinnacles is the subject of debate. Three major theories have been proposed: The first theory states that they were formed as dissolutional remnants of the

Tamala Limestone Tamala Limestone is the geological name given to the widely occurring eolianite limestone deposits on the western coastline of Western Australia, between Shark Bay in the north and nearly to Albany, Western Australia, Albany in the south. The ...

, i.e. that they formed as a result of a period of extensive solutional weathering (

karstification Karst () is a topography formed from the dissolution of soluble carbonate rocks such as limestone and dolomite. It is characterized by features like poljes above and drainage systems with sinkholes and caves underground. There is some eviden ...

). Focused solution initially formed small solutional depressions, mainly solution pipes, which were progressively enlarged over time, resulting in the pinnacle topography. Some pinnacles represent cemented void infills (

microbialites Microbialite is a benthic sedimentary deposit made of carbonate mud (particle diameter less than 5 μm) that is formed with the mediation of microbes. The constituent carbonate mud is a type of '' automicrite'' (or ''authigenic carbonate mud'') ...

and/or re-deposited sand), which are more resistant to

erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

, but dissolution still played the final role in pinnacle development.Lipar, M., 2009. Pinnacle syngenetic karst in Nambung National Park, Western Australia. Acta Carsologica 38 (1), pp. 41–50. A second theory states that they were formed through the preservation of

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...

casts buried in coastal aeolianites, where roots became groundwater conduits, resulting in the precipitation of

indurated In materials science, friability ( ), the condition of being friable, describes the tendency of a solid substance to break into smaller pieces under stress or contact, especially by rubbing. The opposite of friable is indurate. Substances tha ...

(hard)

. Subsequent wind erosion of the aeolianite then exposed the calcrete pillars.Hearty, P.J., O’Leary, M.J., 2008. Carbonate eolianites, quartz sands, and Quaternary sea-level cycles, Western Australia, A chronostratigraphic approach. Quaternary Geochronology 3, 26-55 A third theory suggests that

plants Plants are the eukaryotes that form the kingdom Plantae; they are predominantly photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with cyanobacteria to produce sugars f ...

played an active role in the creation of the Pinnacles, based on the mechanism that formed smaller "root casts" in other parts of the world. As

transpiration Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. It is a passive process that requires no energy expense by the plant. Transpiration also cools plants, c ...

drew water through the soil to the roots, nutrients and other dissolved minerals flowed toward the roota process termed "mass-flow" that can result in the accumulation of nutrients at the surface of the root, if the nutrients arrive in quantities greater than that needed for plant growth. In coastal aeolian sands that consist of large amounts of calcium (derived from marine shells), the movement of water to the roots would drive the flow of calcium to the root surface. This calcium accumulates at high concentrations around the roots and over time is converted into a calcrete. When the roots die, the space occupied by the root is subsequently also filled with a carbonate material derived from the calcium in the former tissue of the roots, and possibly also from water leaching through the structures. Although evidence has been provided for this mechanism in the formation of root casts in

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

, evidence is still required for its role in the formation of the Pinnacles.Cramer MD, Hawkins H-J. 2009. A physiological mechanism for the formation of root casts. Palaeogeography, Palaeoclimatology, Palaeoecology 274: 125–133

Flora and fauna

Western grey kangaroo The western grey kangaroo (''Macropus fuliginosus''), also referred to as a western grey giant kangaroo, black-faced kangaroo, mallee kangaroo, sooty kangaroo and (when referring to the Kangaroo Island subspecies) Kangaroo Island grey kangaroo, i ...

s graze on the vegetation in the park, usually in the early morning. The kangaroos are considered quite tame, sometimes allowing quiet, slow-moving visitors to approach them.

Baudin's black cockatoo Baudin's black cockatoo (''Zanda baudinii''), also known as Baudin's cockatoo or the long-billed black cockatoo, is a species of genus '' Zanda'' found in southwest Australia. The epithet commemorates the French explorer Nicolas Baudin. It has a ...

s and

emu The emu (; ''Dromaius novaehollandiae'') is a species of flightless bird endemism, endemic to Australia, where it is the Tallest extant birds, tallest native bird. It is the only extant taxon, extant member of the genus ''Dromaius'' and the ...

s are frequently observed in the park. Reptiles such as bobtails,

sand goanna The sand goanna (''Varanus gouldii)'', also known commonly as Gould's monitor, the racehorse goanna, and the sand monitor, is a species of large Australian monitor lizard in the family Varanidae. Taxonomy John Edward Gray described the specie ...

s and carpet pythons are a few of the other park inhabitants. Some of the common plant species include panjang (a low-lying wattle), coastal

wattle Wattle or wattles may refer to: Plants *''Acacia sensu lato'', polyphyletic genus of plants commonly known as wattle, especially in Australian English **''Acacia'' ***Black wattle, common name for several species of acacia ***Golden wattle, ''A ...

and banjine,

quandong Quandong, quandang or quondong is a common name for the species ''Santalum acuminatum'' (desert, sweet, Western quandong), especially its edible fruit, but may also refer to: * ''Aceratium concinnum'' (highroot quandong) * ''Peripentadenia mearsi ...

, yellow tailflower, thick-leaved fanflower and cockies tongues.

Parrot bush ''Banksia sessilis'', commonly known as parrot bush, is a species of shrub or tree in the plant genus ''Banksia'' of the family Proteaceae. It had been known as ''Dryandra sessilis'' until 2007, when the genus ''Dryandra'' was sunk into ''Bank ...

, candlestick banksia, firewood banksia and acorn banksia are also common in the park.

Tourism

The Pinnacles remained unknown to most Australians until 1967 when the area was gazetted as a reserve, which was later combined with two adjacent reserves to form

in 1994. Nambung National Park received about 150,000 visitors a year as of 2011. The Pinnacles Desert Discovery Centre was opened in 2008, offering interpretive displays of the park, both the natural processes that formed the Pinnacles and the biodiversity of the area. The best season to visit the Pinnacles is in the months of August to October, as the days are mild and wildflowers, along with

, begin to bloom in the spring. No lodging or camping areas are available within Nambung National Park but accommodations can be found in Cervantes. Pinnacle3

References

External links