Kalinjar Fort - A Potential Geoheritage Site

The Vindhyan sedimentary basin partially wraps around the ∼2500 Ma old Bundelkhand Craton in Central India. The celebrated hill fort of Kalinjar (Kalanjar) is one of the areas where it shows the typical Eparchean unconformity that marks the transition between the Archean and Proterozoic eons in Earth's history. The Kalinjar Fort is situated in the village of Tarahati under the Naraini tehsil, Banda district, in the Bundelkhand region in Uttar Pradesh on the border with Madhya Pradesh. It stands on an isolated flat-topped hill comprised of Kaimur sandstone resting unconformably over the Bundelkhand granitoid Complex (BGC), which rises 244m above the plain. The Chandela Fort is aligned in an east-west direction, being nearly 2km in length and 800m in breadth. It is built on strong 25-30m wide foundations and has a height of around 30-25m with 8m wide summit. The material used in its construction is the large sandstone and granite pieces derived from the nearby localities.

The Kalinjar Fort is one of the largest and unbeatable forts of medieval India, which incorporates many styles of architecture in this fort viz. the Gupta style, Pratihara style, Panchayatan Nagar style etc. The name of Kalanjaradri, or the hill of Kalinjara, is said to have been derived from Siva himself, who, as Kala, or "Time", causes all things to decay (jar), and who is, therefore, the destroyer of all things, and the god of death. There are two entrances to the fort of Kalinjar, of which the principal is on the north side and the other at the southeast end leading towards Panna. Besides architectural antiquity, there are several mythological places and sculptures within the fort premises. One of the small caves, called as Sitasej, contains a stone bed and pillow. The Patal Ganga is a large deep well, or reservoir, cut in the rock, while the Pandu-kund is a shallow circular basin, about 12 feet in diameter, into which the water is constantly trickling from the crevices. There is a colossal figure of Kal Bhairav, which has 18 arms with the usual garland of skulls, snake earrings, snake armlets and a serpent twined around the neck. Several broken pieces of sacred sculpture tell about the cultural richness and diversity as most are centuries old.

Geologically, the Vindhyan sedimentary basin is one of the largest repositories of undeformed sediments deposited over a long time. Approximately 800m before the main entrance of the fort, the geological boundary is between sedimentary rocks of the Vindhyan Supergroup, 1400 million years old, and Archaean rocks comprising granites that are more than 2000 million years old. This boundary represents an area that witnessed a significant change in the Earth's tectonics and climate systems. It is characterized by a period of erosion and non-deposition that led to the formation of nonconformity, where the older Archean rocks are overlain by relatively younger Proterozoic rocks deposited in one of the Purana basins. This unconformity separates the Proterozoic Kaimur sandstone (1200 Ma) and Bundelkhand granite (more than 2000 Ma) with relatively younger intrusive dolerite dykes, representing a time gap of approx. 600 Ma, which is a period of remarkable gap in geological history. This unconformity indicates the enormous time gap in the creation of the earth's crust.

The approach road from the village Tarahati to Kalinjar Fort provides an opportunity to attract potential visitors for its geological importance before looking into the history and architecture of the fort. The road maintenance, vegetation expansion, and irresponsibility of occasional visitors (rock graffiti and littering) are potential dangers to this geo-heritage site. As the fort is conserved and maintained by the Archaeological Survey of India (ASI), a suitably designed conservation plan expressing its geological importance of this geoheritage site, also needs to be developed to address these issues.

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