Approximately 650,000 years ago, an outer space object–either a comet or a meteor– struck the Deccan plateau (an immense basaltic flow on the Indian subcontinent dating back to the twilight of the dinosaurs). The resultant crater in Maharashtra is now the sight of a very interesting saltwater lake, Lake Lonar. The geology of this region has been intensely studied because the great basaltic mass of the Deccan traps is thought to mirror the igneous geology of Mars and the moon.
Lake Lonar proper is nearly circular with a diameter of 1.2 kilometers. The greater meteor crater rim is about 1.8 kilometers and the crater measures 500 feet deep in the deepest part of the lake. In addition to the obvious features of an extraterrestrial impact (um, a large round hole), the region features many other unique geological signs of such an event. Maskelynite, a material only naturally known from meteorites and meteorite impact areas, is found around Lake Lonar, as are silicate minerals with planar deformation features (distinctive high-stress crystalline irregularities which have only been found in silicates from meteorites, craters, and nuclear test areas). The deeper geology of the lake region displays shatter cones in the bedrock, and extreme deformation of the basalt layers. Finally the surrounding region has been spattered with a non-volcanic ejecta blanket.
By measuring the accumulated radiation in certain crystals (aka thermoluminescence) scientists had assigned an approximate age of 50,000 years to the crater. However a 2010 study of isotopic Argon in Lonar impact melt rock estimated the true time of impact to be 650,000 years ago (give or take 80,000 years). The compelling 2010 study drily notes “The discrepancy between the thermoluminescence age and the new isotopic 40/Ar/39Ar age is flagrant.”
Several abandoned temples and archaeological sights are also located around the lake. For example, the beautiful Daitya Sudan Temple to Vishnu was built by the Chalukya Dynasty which ruled of Maharashtra from the 6th and 12th centuries. The local town, Lonar, still has an active temple to Vishnu, the great protector of the universe who features prominently in local legend. According to the Skanda Purana (a canon of Hindu scripture universally cited when a story is doubtful or can not be found elsewhere) a great underworld demon, Lonasur, lived where Lake Lonar is today. From time to time the demon would venture from his subterranean abode to torment the countryside and challenge the gods. Assuming the form of an extremely beautiful young man, Vishnu…somehow convinced the demon’s sisters to divulge where the monster could be found. The god then lifted up the countryside like a great lid and found the demon hiding in his huge circular lair. After Vishnu slew the demon, the demon’s dwelling place filled up with water made salty by the fiend’s blood.
Although threatened by India’s ever growing sprawl, Lonar Lake is a rich wetland with abundant wildlife—particularly birds. The jungles, fields, and lake are a birder’s paradise featuring flamingos, grebes, black-winged stilts, dabchicks, ducks, shell-ducks, shovellers, teals, herons, rollers, parakeets, hoopoes, weavers, larks, tailorbirds, magpies, robins, swallows, peacocks, coots, white-necked storks, lapwings, grey wagtails, black droungos, green bee-eaters, and tailorbirds (to name just some).