Hyderabad: Bhongir outside Hyderabad has one of the largest exposed portions of a batholith in the world, which has rich archaeological significance. Batholiths are large geological formations of rocks created from cooling of magma.
Dr J. Rantakar of Osmania University’s geology department said the hill on which the Bhongir fort is located is an exposed part of a batholith designated as Eastern Dharwar Craton. It’s 2.5 to 2.7 billion years old. Such hills are exposed after billions of years of erosion.
He said the craton extends thousands of square kilometers beneath the earth’s crust, covering districts in Karnataka, Tamil Nadu, Telangana, and Maharashtra and shares boundary with the Eastern Ghats in Andhra Pradesh.
A search on the Internet will yield many results for the term ‘batholith’, including some exposed portions of batholith with high touristic value like Uluru in Australia, a Unesco World Heritage Site.
The Uluru formation is sometimes listed as the largest in the world. However, the batholith at Bhongir is 388 feet taller, at 1,410 feet with a circumference of 9.63 km. It rarely finds mention.
Mr D. Satyanarayana, a historian from the city who recently released a coffee table book on Bhongir, said, “Apart from being one of the largest exposed batholith portions in the world, the hill has a rich history. It was occupied by humans as long back as 3,000 years ago, during the Mesolithic Age.
A temple built by them still exists there. A petroglyph at the temple which represents the universe, also known as Bhuvana, is the real reason why the place is known as Bhuvanagiri and not because of the Tribhuvanamalla king as many believe. The fort was built around 5th Century AD.”