| Lonar Lake | |
|---|---|
| Lonar crater full rim view with vegetation | |
| Location | Buldana district, Maharashtra |
| Lake type | impact crater lake, salt lake |
| Basin countries | India |
| Surface area | 1800 meters |
| Average depth | 150 meters |
Lonar Lake is a saltwater lake at Lonar in Buldana district, Maharashtra, India, which was created by a meteor hitting the Earth during the Pleistocene Epoch.[1] The impact crater thereby formed is the only hypervelocity meteoritic impact crater on basalt rock.[2][3] A lake that evolved in the resulting basaltic rock formation, is both saline and alkaline in nature. Geologists, ecologists, archaeologists, naturalists and astronomers have reported several studies on the various aspects of this crater lake ecosystem.[4] Lonar Lake has a mean diameter of 1.2 kilometres (3,900 ft) and is about 137 metres (449 ft) below the crater rim. The meteor crater rim is about 1.8 kilometres (5,900 ft) in diameter. The circular depression bears a saline water lake in its central portion.[5] The crater's age is usually estimated to be 52,000 ± 6,000 years (Pleistocene),[6] although a study published in 2010 gives an age of 656,000 ± 81,000 years.[7]
The Smithsonian Institution, the United States Geological Survey, Geological Society of India, and University of Sagar and the Physical Research Laboratory have conducted extensive studies about the site.[2][8]
Biological nitrogen fixation has been discovered in this lake in the year 2007.[9]
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A series of low hills surround the basin which has an oval shape (almost round) with circumference at top of about 8 km (five miles). The sides of the basin rises abruptly at an angle of about 75°. At the base, the lake has a circumference of about 4.8 km (three miles). The slopes are covered with jungle interspersed with teak tree. A belt of large trees about a mile broad runs all round the basin; belt is formed of concentric rings of different species of trees. A ring of date-palms followed by a ring of tamarind trees (nearly 1.6 km or a mile broad) leads to a ring of babul trees, bounded on the inside by a belt of bare muddy space; mud space is several hundred metres/yards broad, devoid of all vegetation (due to soda content in the water) and covered with a whitish slimy soil, and leads to the lake water. During the rainy season, the drainage into the lake covers the muddy space. The water of the lake contains various salts or sodas. During the dry weather, as the water level reduces with evaporation, large quantities of sodas are collected. A well of sweet water is also located on the southern side of the lake, close to lake's water edge Two small streams drain into the lake.[10]
The historical document called the Ain-i-Akbari (written about A.D. 1600) states: These mountains produce all the requisites for making glass and soap. And here are saltpetre works which yield a considerable revenue to the State, from the duties collected. On these mountains is a spring of salt water, but the water from the centre and the edges is perfectly fresh.[10]
The lake is said to be the only crater in the great basaltic formation of India. The lake was initially believed to be of volcanic origin, but now it is recognized as an impact crater created by the hypervelocity impact of either a comet or a meteorite. The presence of plagioclase that has been either converted into maskelynite or contains planar deformation features (PDFs) has confirmed the impact origin of this crater. It is argued that only shock metamorphism caused by hypervelocity impact can transform plagioclase into maskelynite or create PDFs. The presence of shatter cones, impact deformation of basalt layers comprising its rim, shocked breccia inside the crater, and non-volcanic ejecta blanket surrounding the crater are further proof of the impact origin of Lonar crater. As a result of the studies, broadly, the geological features of the Lonar crater has been marked under five distinguishable zones, exhibiting distinct geomorphic characteristics.[11]
The five zones are:[12]
The lake was first mentioned in ancient scriptures such as the Skanda Purana, the Padma Puran and the Aaina-i-Akbari [13] The first European to visit the lake was British officer, J.E. Alexander in 1823.
Buldhana district in Maharashtra where the lake is located was once part of Ashoka's empire and then of Satavahanas. The Chalukyas and Rashtrakutas also ruled this area. During the period of the Mughals, Yadavas, Nizam and the British, trade prospered in this area. Several temples found in the periphery of the Lake are known as Yadava temples and also as Hemadpanti temples (named after Hemadri Ramgaya).[14]
A legend given in the Gazetteer of talukas, towns, important villages, rivers and hills published by the Gazeteers department of Government of Maharashtra [15] states:
As per Skanda Purana, a demon named Lonasura who lived in a subterranean abode used to devastate the surrounding country and even challenge Gods. Lord Vishnu, on an appeal by the people of the region, assumed the form of a handsome youth named Daitya-sudan, charmed the giant's two sisters and discovered the giant's abode and then removed the lid of the den where he was hiding and destroyed the giant. The present lake is claimed to be the den of the giant, and a conical hill near the village Datephal, some 36 miles to the south-west, is said to be the lid of the giant's den. The water of the lake is likened to the blood of the giant and the salts that it contains as the decomposed flesh of the giant. It is also believed that a perennial spring, at the head of the path which leads down to the lake is linked to the Ganges river.
Numerous temples surround the lake, most of which are in ruins, except for the temple of Daityasudan, at the centre of the Lonar town, which was built in honour of Vishnu's victory over the giant Lonasur. It is a fine specimen of early Hindu architecture.[16] Vishnumandir, Wagh Mahadev, Mora Mahadev, Munglyacha Mandir and Goddess Kamalaja Devia are the other temples found inside the crater.[17]
Daitya Sudan Temple has beautiful carvings similar to what is seen at Khajuraho temples. The idol of this temple is made of an ore with high metal content and looks like stone. Area out-side the sanctum is dark and the ceiling reveals beautiful carvings under a torch light. It is a Vishnu temple dated to the Chalukya Dynasty which ruled Central and Southern India between the 6th and 12th centuries. It belongs to the Hemadpanthi class and is built in the form of an irregular star. The exterior walls are covered with carved figurnes. The plinth of the temple is about 1.5 m in height, and the unfinished roof suggests an intended pyramidal form for the tower.
Gomukh Temple, is located along the rim of the crater. A perennial stream emerges from here and pilgrims visiting the temple bathe in the stream.[18]
The Gazetteer chronicles the findings of the British administrators and scientists, notably, Colonel Mackenzie, Scientist Dr. I. B. Lyon, Mr. J. O. Malcolmson and Mr. Plymen, Agricultural Chemist. Some extracts from Mr Plymen's report, given in quotes, are informative.[19]
The saline deposits obtained from the lake are rather of an exceptional nature. Compared with the most famous salt lake in India, the Sambhar Lake in Rajputana, it will be seen that whereas at Lonar the carbonates of soda are the most important, in the case of the Sambhar Lake the deposits of sodium chloride or common salt give the lake its value. The modes of formation are also entirely different and it is practically certain that the Lonar salts are derived from an unknown source in the bed of the lake. It is true that water is continually flowing into the lake and that except by evaporation there is no loss. The main feeder stream could not however supply this amount of alkali nor could the other smaller supplies coming in during the rains, for on all sides of the lake vegetation is abundant, particularly where the main stream flows in continuously. Were any quantity of alkali present in this water, vegetation would suffer considerably and, with exception of a few varieties of plants, eventually die out entirely.
The salts collected from this lake vary in their nature and composition and from their-appearance are easily separated by men accustomed to handling them. Various names are given to some five or six main varieties, but there is no fixed line between one salt and another, their compositions depending upon the period and condition of crystallization. At the present time large quantities of these salts are lying on the shores of the lake...
With the process of crystallization, sodium chloride or common salt is formed along with the carbonates of soda resulting in a number of products, as explained below.[19]
Dalla Nimak and Nimak Dalla are found in white crystalline masses.
Khuppal is obtained in solid compact lumps and consists of a mixture of carbonates and chlorides in roughly equal proportions.
Pipadi or Papri, which has a similar chemical composition, is very different in appearance. It is frequently tinged, slightly pink in colour and hollow air spaces are found between the crystalline masses which are formed in flakes or layers.
Bhuski has no definite structure but consists of a soft flaky powder mixed with a quantity of impurity.
All the salts are not obtained in the same way or at the same period of the year. Pipadi and Bhuski are deposited on the shores of the lake as the water dries up in the hot weather, Pipadi being the upper layer and therefore the purer. Except for Bhuski the salts are in a fairly pure state and contain only small proportions of earthy matter. Their further purification is not considered difficult.[19]
Commercial exploitation of the salts from the lake, is recorded from 1842 including the period of Government of His Highness Nizam, and till 1903. Presently, there is only a very small local demand for the Lonar Lake products.[19]
The chemical characteristics of the lake shows two distinct regions that don’t mix - an outer neutral (pH 7) and an inner alkaline (pH 11) each with its own flora and fauna. The lake is a haven for a wide range of plant and animal life. Resident and migratory birds such as black-winged stilts, brahminy ducks, grebes, shell-ducks (European migrants), shovellers, teals, herons, red-wattled lapwings, rollers or blue jays, baya weavers, parakeet hoopoes, larks, tailorbirds, magpies and robins and swallows are found on the lake. Among reptiles, the monitor lizard is reported to be prominent. The lake is also home to thousands of pea fowls, chinkara and gazelles.[20] Plea to declare Lonar lake a protected wetland.
Nonsymbiotic nitrogen fixing microorganisms such as Halomonas sp., Paracoccus sp. Klebsiella sp., Slackia sp. Actinopolyspora sp. have been reported from this lake. All the nitrogen fixers are haloalkaliphilic in nature as they can grow only at pH-11. Some of the bacteria and actinomycetes isolated from this lake are able to grow on some components of inorganic medium containing martian soil simulant components.[21]
Lonar lake of faces anthropological and environmental problems as listed below:
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