Blue Lake / Warwar (The Blue Lake) is a large,

monomictic Monomictic lakes are holomictic lakes that mix from top to bottom during one mixing period each year. Monomictic lakes may be subdivided into cold and warm types. Cold monomictic lakes Cold monomictic lakes are lakes that are covered by ice thro ...

crater lake Crater Lake (Klamath language, Klamath: ''Giiwas'') is a volcanic crater lake in south-central Oregon in the western United States. It is the main feature of Crater Lake National Park and is famous for its deep blue color and water clarity. The ...

located in a dormant volcanic

maar A maar is a broad, low-relief volcanic crater caused by a phreatomagmatic eruption (an explosion which occurs when groundwater comes into contact with hot lava or magma). A maar characteristically fills with water to form a relatively shallow ...

associated with the Mount Gambier maar complex. The lake is situated near in the

Limestone Coast The Limestone Coast is a name used since the early twenty-first century for a South Australian government region located in the south east of South Australia which immediately adjoins the continental coastline and the Victorian border. The ...

region of

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

, and is one of four

volcanic crater lake A volcanic crater lake is a lake in a crater that was formed by explosive activity or a collapse during a volcanic eruption. Formation Lakes in calderas fill large craters formed by the collapse of a volcano during an eruption. Lakes in maars ...

s originally on Mount Gambier maar. Of the four lakes, only two remain, the other one being Valley Lake / Ketla Malpi; the other two, Leg of Mutton Lake / Yatton Loo and Brownes Lake / Kroweratwari, have dried up as the water table has dropped.

History

Conflicting dates have been estimated for the last eruption of the volcano: of 4,300 years ago, of 28,000 years ago, and a little before 6,000 years ago. If the youngest date is correct, this could be the most recent volcanic eruption on the Australian mainland. The

Boandik The Bungandidj people are an Aboriginal Australian people from the Mount Gambier region in south-eastern South Australia, and also in western Victoria. Their language is the Bungandidj language. Bungandidj was historically frequently rendered a ...

(or Bungandidj) people occupied the area before the

colonisation of South Australia British colonisation of South Australia describes the planning and establishment of the colony of South Australia by the British government, covering the period from 1829, when the idea was raised by the then-imprisoned Edward Gibbon Wakefield ...

Description

Blue Lake / Warwar is one of four lakes in the

extinct volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are ...

complex. Sites of cultural significance to the Boandik people were assigned

dual name Dual naming is the adoption of an official place name that combines two earlier names, or uses both names, often to resolve a disagreement over which of the two individual names is more appropriate. In some cases, the reasons are political. Some ...

s by the

City of Mount Gambier The City of Mount Gambier is a local government area centred in Mount Gambier in the Limestone Coast region of South Australia. While it is the southernmost ''city'' council in the state, the District Council of Grant is the southernmost counci ...

in February 2022, and the renaming included the four lakes in the

Bungandidj language Bungandidj is a language of Australia, spoken by the Bungandidj people, Indigenous Australians who lived in an area which is now in south-eastern South Australia and in south-western Victoria. According to Christina Smith and her book on the B ...

. These are as follows: *Blue Lake / Warwar, meaning "crow country" * Leg of Mutton Lake / Yatton Loo * Brownes Lake / Kroweratwari, meaning "emus, rtheir tracks" * Valley Lake / Ketla Malpi, meaning "sacred talking tree" Blue Lake is thought to be of an average depth of , but in places reaches deep (but some unconfirmed values mention a maximum depth due to a natural cave section). The crater rim measures , but the lake itself measures . The surface of the lake is below the level of the main street of the nearby town. The Blue Lake supplies the town with drinking water. Browne's Lake / Kroweratwari (sometimes spelt Browns Lake) dried up in the 1980s, and is now a picnic spot. There is a road and walking track around the circumference of Blue Lake / Warwar, with an underpass between it and Leg of Mutton Lake / Yatton Loo.

Annual colour change

Blue Lake in Mount Gambier South Australia

Each November, the lake turns to a deep

turquoise Turquoise is an opaque, blue-to-green mineral that is a hydrated phosphate of copper and aluminium, with the chemical formula . It is rare and valuable in finer grades and has been prized as a gemstone and ornamental stone for thousands of yea ...

colour, gradually returning to a duller blue colour in late February to March. The exact cause of this phenomenon is still a matter of conjecture, but likely it involves the warming of the surface layers of the lake during the summer to around , causing calcium carbonate to

precipitate In an aqueous solution, precipitation is the process of transforming a dissolved substance into an insoluble solid from a super-saturated solution. The solid formed is called the precipitate. In case of an inorganic chemical reaction leading ...

out of the

solution Solution may refer to: * Solution (chemistry), a mixture where one substance is dissolved in another * Solution (equation), in mathematics ** Numerical solution, in numerical analysis, approximate solutions within specified error bounds * Soluti ...

and enabling micro

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

lites of calcium carbonate to form. This results in scatter of the blue

wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tro ...

s of sunlight. During winter, the lake becomes well mixed, and recent research indicates that during this phase of the colour cycle, the lake is somewhat murkier due to the redistribution of tannins and calcium carbonate particles throughout the lake. Solar elevation has also been found to influence the perceived colour of the lake. The movement of planktonic life forms within the lake during the

seasons A season is a division of the year based on changes in weather, ecology, and the number of daylight hours in a given region. On Earth, seasons are the result of the axial parallelism of Earth's tilted orbit around the Sun. In temperate and po ...

and during the day may additionally play a part in the colour change.

Studies

Bathymetric Bathymetry (; ) is the study of underwater depth of ocean floors (''seabed topography''), lake floors, or river floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography. The first recorded evidence of water d ...

surveys located the deepest point in the lake at in 1967. Major diving exploration of the lake first occurred in 1985. Cave diver Peter Horne conducted temperature and visibility studies and made discoveries of a freshwater sponge species and other invertebrates. This exploration also discovered the

Stromatolite Stromatolites () or stromatoliths () are layered sedimentary formations (microbialite) that are created mainly by photosynthetic microorganisms such as cyanobacteria, sulfate-reducing bacteria, and Pseudomonadota (formerly proteobacteria). The ...

Field, a collection of hollow rock formations that are found along the north-eastern perimeter down to a depth of . In 2008, permission was granted by

SA Water SA Water is a government business enterprise wholly owned by the Government of South Australia. History SA Water was established by the proclamation of the ''South Australian Water Corporation Act 1994'' on 1 July 1995. Prior to this its predec ...

for another diving exploration of the central and deepest parts of the lake. On this dive, core samples from the

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

-silt covered lake bed were collected where water temperature drops to .

Gordon's leap

In July 1865,

Adam Lindsay Gordon Adam Lindsay Gordon (19 October 1833 – 24 June 1870) was a British-Australian poet, horseman, police officer and politician. He was the first Australian poet to gain considerable recognition overseas, and according to his contemporary, write ...

performed the daring riding feat known as Gordon's Leap on the edge of the Blue Lake. A commemorative obelisk erected there has an inscription which reads:

This obelisk was erected as a memorial to the famous Australian poet. From near this spot in July, 1865, Gordon made his famed leap on horseback over an old post and rail guard fence onto a narrow ledge overlooking the Blue Lake and jumped back again onto the roadway. The foundation stone of the Gordon Memorial Obelisk was laid on 8th July 1887

Gallery

Image:Mount Gambier Blue Lake closeup.jpg, About above the lake's surface Image:Mount Gambier Blue Lake2.jpg, The lake in early March with the original pumping station in the foreground

History

Description

Annual colour change

Studies

Gordon's leap

Gallery

See also

References

Further reading