A 50,000-Year-Old Crater Lake Recently Turned Pink to the Amazement of Scientists

The year 2020 has put another curveball in our path, in the form of a color-changing lake.  Lonar Lake is under the influence of a meteorite in the Indian state of Maharashtra, about 500 km (311 miles) east of Mumbai, and dates from about 50,000 years ago (although recent dating suggests it may be much older).  Earlier, the lake’s normal bluish-green hue turned reddish-pink, further testing is needed to determine the exact cause; experts suggest that changes in salt levels and the presence of certain algae in the lake may be to blame.

According to local knowledge and records, similar color-changes were observed around 2000 but were not noticed or were not so prominent. This time, the lake water samples have been sent to the National Institute of Environmental Engineering Research (NERI) for analysis to uncover the exact cause of the incident. Meanwhile, local geologist Gajanan Kharat shared his explanation in a video on Maharashtra Tourism’s Twitter feed.

Kharat was quoted as saying by AFP, “The salinity of the lake has increased this year as the water level has dropped drastically and the algae have increased, making it even warmer.” “These algae turn red in warm temperatures and so the lake turns pink overnight.”

Indeed, other experts, such as Professor Suresh Mapari, advised the local newspaper Lokmat that Halobacteria and Dunaliella salina were guilty of releasing a red pigment (carotenoid) by a large inflorescence of algae. For him though, the trigger for this currently remains unchallenged. 

The 150-meter-deep (500-foot) and 1.8-kilometer-wide (1.12-mile) impact groove is one of the most well-known basaltic rocks anywhere on Earth.  When the hole was originally discovered in the 19th century, it caused some confusion with geologists, who believed it was the source of the volcano. However, this hole has been attributed to a cosmic effect due to the presence of maskelynite, a naturally formed glass formed only by extremely high-velocity effects. Scientists around the world are curious about both the crater and its lake. The water itself was found to be both alkaline and saline and in 2007 evidence for the determination of organic nitrogen (conversion of atmospheric nitrogen to ammonia) was found. This recent development will surely add another colorful chapter to the history of Lonar Lakes.