Blue Lake (South Australia)
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| Blue Lake | |
|---|---|
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| Location | Mount Gambier, South Australia |
| Coordinates | |
| Lake type | Crater Lake |
| Basin countries | Australia |
| Average depth | 70 m |
The Blue Lake ( ) in Mount Gambier is a large monomictic lake located in an extinct volcanic maar associated with the Mount Gambier maar complex. It is known as Waawor in the local Aboriginal language.
Conflicting dates have been estimated for its last eruption, of 28,000 years ago[1] and 4300 years ago.[2] If the more recent date is correct, this could be the most recent volcanic eruption on the Australian mainland.
During December to March, the lake turns to a vibrant cobalt blue colour, returning to a colder steel grey colour for April to November. The exact cause of this phenomenon is still a matter of conjecture but it is generally considered likely that it revolves around the warming of the surface layers of the lake during the summer months to around 20 degrees °C, causing calcium carbonate to precipitate out of solution and enabling micro-crystallites of calcium carbonate to form. This results in scatter of the blue wavelength 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 and during the day may also play a part in the visibility changes.
The Blue Lake supplies the town with drinking water, providing approximately 3,600 ML per year from its 36,000 ML store. Its average depth is 70 m.
[edit] Gallery
 The Blue Lake in early March. |
 The Blue Lake in early March. |
 The Blue Lake in early March. |
 Approximately 4 metres above the lake's surface. |
 Panorama of the Blue Lake in mid-December. |
Blue Lake thought to be at least 75 meters deep(250 feet)is one of three crater lakes on Mount Gambier. Although the crater rim measures 20 meters (66 feet), due to the lakes great depth, the bottom of the lake is 30 meters(100 feet) below the level of the main street of the near by town. Each year a festival is held when the lake turns blue.
[edit] References
- ^ Grimes, Ken (2007). The Ages of Our Volcanoes. Retrieved on 2008-05-07.
- ^ Volcanoes & Earthquakes in SE Australia. University of Western Australia. Retrieved on 2008-05-07.
- Sheard, M.J. (1978) Geological History of the Mount Gambier Volcanic Complex, Southeast South Australia. Transcript from Royal Society of South Australia 102(5), Aug. 1978
- Telfer, A. (2000) Identification of processes regulating the colour and colour change in an oligotrophic, hardwater, groundwater-fed lake, Blue Lake, Mount Gambier, South Australia. Lakes and Reservoirs: Research and Management. 5 161-176.
- Turoczy, N.J. (2002) Calcium chemistry of Blue Lake, Mt Gambier, Australia, and relevance to remarkable seasonal colour changes. Archiv fur Hydrobiologia. 156 (1) 1-9.
- Emeny, J., Turner, G., Turoczy, N.J. and Stagnitti, F. (2006) The influence of weather and solar elevation on perceived colour of Blue Lake, Mount Gambier, South Australia. Transactions of the Royal Society of South Australia. 130(1) 101-108.
