IMPACT CRATERS IN INDIA
There are two two large meteorite impact craters in India. One of these, unequivocally of meteoritic origin is the Lonar Crater in Buldana istrict of Maharashtra, while the other, of possibly meteoritic origin is located in the Baran district of Rajasthan.
One of the two known meteorite impact craters in India is the nearly circular, bowl shaped crater, located in Buldhana district of Maharashtra in the extensive Deccan Volcanic Province (DVP). Measuring almost exactly 2.0 km from rim to rim, the crater is partially filled by a salty, alkaline lake 1,200 meters in diameter. Early investigators of this unique geomorphic feature ascribed its origin to some form of explosion or subsidence. Although developed in the Deccan flood basalts, the crater cannot be genetically related to these traps which were extruded during the Cretaceous. The youthfulness of this structure indicates its origin long after the cessation of Deccan volcanic activity. Recent researches have tended to support the view that the Lonar structure is probably a hypervelocity impact crater of Quarternary age. This view is borne by the high degree of circularity, the depth to diameter ratio, the thick layers of breccias constituting the rim and overlying paleosols, the quaquaversal dip of surrounding country rock, and the mounds of debris lying around the crater rim. The regional dip is zero. The crater wall dips between 5 and 25°, with overturn observed in the rim fold.
The large variation in estimated ages of the crater ranging from some 13,000 years to about 52,000 years adds to the uncertainties that surround the age of impact and demands further investigations.
The lake occupying the Lonar Crater 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. Lonar Lake has a mean diameter of 1.2 kilometres and is about 137 metres below the crater rim.
Lonar Crater is an excellent site for studies of impact crater formation and deformation, shock magnetization, and fluidized ejecta. An detailed account of the geological and structural details of Lonar Crater can be found here:
The monotony of the vast stretch of almost horizontally-bedded Neoproterozoic Vindhyan sediments in south eastern Rajasthan is broken by an elevated circular physiographic structure occurring near Ramgarh village (about 12 km east of Mangrol) in Baran district. Due to its nearly 200 m elevation above surrounding terrain, it can be spotted from a distance of 40 km. The crater has a diameter of 2.7 km. Elevation on the eastern side of the rim is 440 m, while the western side, at 360 m is considerably lower. The crater has a maximum slope of 30o in the southern part.
This unusual rocky structure attracted the attention of geologists since its discovery. It falls in Survey of India toposheet 54 C/ 11 and is situated about 110 km ENE of Kota. It can be approached via Jaipur-Tonk-Indergarh-Mangrol, Alwar-Gangapur-Sawai Madhopur-Sheopur-Mangrol and Kota-Baran-Mangrol road routes. The Ramgarh Crater is known by many othe names, viz., ‘Ramgarh structure’, ‘Ramgarh meteoritic structure’, ‘Ramgarh ring structure’, ‘Ramgarh dome’, ‘Ramgarh dome structure’, ‘Ramgarh astrobleme’, etc.
Detailed studies f this structure have not been made. However, in all likelihood it is an impact crater. A detailed multidisciplinary study is necessary to evaluate the structure and lithology of Ramgarh Crater.
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