Lonar
Key facts
- Country
- India
- Diameter
- 1.83 km
- Age
- about 570,000 years
- Location
- 19.98° N, 76.51° E
A steep-sided bowl about 1.8 km across and some 150 m deep, cut into black basalt, with a saline, alkaline lake on its floor and old temples around its slopes.
Lonar Crater, in the Buldhana district of Maharashtra in western India, is one of the few well-preserved impact craters formed in basalt, the dark volcanic rock that covers much of the Moon's maria and large areas of Mars. That makes it especially valuable to planetary scientists, who use it to understand craters on other worlds.
The impact. The crater is about 1.83 km wide and about 150 m deep, with a raised rim. It was blasted into the Deccan Traps, a vast pile of lava flows that erupted around 66 million years ago. For many years Lonar was thought to be only about 50,000 years old. In 2011 a study using argon–argon dating of impact melt rock suggested a much older age, about 570,000 years. Scientists continue to refine the date, so it is fair to say the crater is several hundred thousand years old.
Proving an impact. Lonar was long debated: was it a volcanic crater or an impact? In the 1970s scientists found maskelynite, a glass formed when the mineral plagioclase is struck by intense shock, and other shock features, confirming an impact origin. Glass spherules and shocked rock fragments have since been found in the ejecta.
A remarkable lake. A shallow lake fills the crater floor. Its water is both salty and strongly alkaline, an unusual combination that supports specialised microorganisms. In June 2020 the lake suddenly turned pink, attracting national attention. Scientists linked the change to a bloom of salt-loving microorganisms called haloarchaea, encouraged by evaporation and warm weather. The colour faded after the monsoon rains diluted the water.
In 2020 the lake was designated a Ramsar site, a wetland of international importance.
Temples and legends. The crater has been a place of pilgrimage for many centuries. Old temples, some built many hundreds of years ago, stand around the rim and slopes, and it features in local legends and is said to be mentioned in old Hindu texts. One story tells of a demon called Lonasura who was defeated by the god Vishnu here, giving the crater its name. A freshwater spring on the slopes feeds a stream that flows into the lake.
Visiting. Lonar is a protected site, and a footpath leads down from the rim to the lake and temples. The crater forest is home to birds, monkeys and other wildlife. As with any protected site, rocks and glass should not be removed. The best time to visit is after the monsoon, when the crater is green.
Did you know?
Lonar is one of very few young impact craters formed in basalt, the rock of the lunar maria.
Its lake turned pink in 2020 because of a bloom of salt-loving microorganisms.
Dating published in 2011 suggested the crater is about ten times older than once thought.