Lonar Lake, also referred to as Lonar crater, is a recognised National Geo-heritage location, a salty soda lake near Lonar in Buldhana, Maharashtra district. Geo-heritage refers to intrinsically or culturally significant geological characteristics that provide insight into Earth’s evolution or history or may be used for learning. The Geological Survey of India (GSI) is the primary agency for identifying and protecting geo-heritage sites.
It is located within the Deccan Plateau, a vast expanse of volcanic basalt rock formed by eruptions. It is thought to have formed approximately 52,000 years ago when a meteorite collided with the Earth. It is made of basaltic rock and has a diameter of 1.85 kilometres and a depth of 500 feet.
Geographical origin
- Lonar Lake is located amid the enormous Deccan Traps, a massive basaltic deposit in India, and is the only known interplanetary impact crater in India.
- The lake was once considered volcanic in origin, but it is now recognised as an impact crater.
- As a result of the collision of a comet or an asteroid, Lonar Lake was formed.
- The presence of plagioclase, which has either been transformed into maskelynite or exhibits planar deformation patterns, has proven the crater’s impact origin.
- Shock metamorphism high-velocity impacts are the only process capable of transforming plagioclase into maskelynite and producing planar deformation patterns.
- The crater is oval in structure. In addition, the meteorite struck at an inclination of 35 to 40 degrees from the east.
Historical Background
The lake initially appears in ancient texts such as the Padma and the Skanda Purana. According to the Ain-i-Akbari’s text published in 1600 CE, “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 saltwater spring, but the water from the centre and the edges is perfectly fresh.”
Intriguingly, the lake’s location in Maharashtra’s Buldhana district was formerly the territory of the Maurya Empire and, subsequently, the Satavahana Empire. Furthermore, this region was also governed by the Chalukyas and Rashtrakutas. Trade flourished in this region throughout the reigns of the Mughals, the Yadavas, and the British.
Colour Shift in 2020
- In 2020, it was discovered that the water in Lonar lake in Maharashtra’s Buldhana district was turning red.
- The district administration has recommended that the National Environmental Engineering Research Institute (NEERI), Nagpur, investigate the cause.
Important points to remember
- The water of Maharashtra’s Lonar lake, popularly known as the Lonar crater, has turned crimson\ red.
- When the lake receives rain, it is considered normal.
What are the reasons behind the shift in colour?
Algal Bloom:
- An algal bloom, also known as an algae bloom, is a fast rise or accumulation of algae in fresh or marine water systems commonly identified by water discolouration.
- The colour change is often ascribed to algae bloom in the lake during the monsoon season.
Salinity Change:
- The salinity of the water has elevated due to evaporation. As a result, it is thought to be a factor in the colour shift.
Biological Shift:
- The colour change appears to be a biological change in the Lonar crater because there was no disturbance to the lake throughout the lockdown phase, and it naturally turned red.
According to reports from the Agharkar Research Institute, the National Environmental Engineering Research Institute, and the Geological Survey of India, low water levels and high salinity stimulated the development of Halobacterium. It raised Carotenoid levels, resulting in a colour shift.
