Kaimur Sandstone of Vindhyan Supergroup: a Prevalent Prehistoric and Ancient Monumental Heritage Stone from Son Valley of Central India

The Mesoproterozoic Kaimur Sandstone belonging to the Vindhyan Supergroup has been used in several significant heritage structures covering a vast expanse of Son Valley in Central India. Geologically, Kaimur Group comprises six formations (in ascending order) namely Sasaram Sandstone, Ghurma Shale, Markundi Sandstone, Bijaigarh Shale, Scarp Sandstone, and Dhandraul Sandstone. It is quite likely that all the five variants of Kaimur Group sandstones (excluding Bijaigarh Shale) were being utilized by local people as heritage stone at different times in the past. However, Scarp Sandstone and Dhandraul Sandstone formations have been extensively used as building material due to their variegated colours, stratigraphic thickness and wide exposure, low porosity, hardness, compactness, mechanical durability, and high tensile and compressive strength as compared to other variants. These sandstones are commercially known by their trade name — Chunar Sandstone which is locally called as Chunar balua patthar , Balua patthar , Pattiya patthar , and Baad . In 2019, Chunar Balua Patthar was granted GI tag. Chunar Sandstone has been widely used as in situ rock shelters, carved sculptures of deities, in temples, forts, heritage buildings, and monuments and also as art and architectural elements from prehistoric and historic times. This sandstone has been used in ancient and contemporary places of worship of different faiths in eastern and central India, river embankments locally called as ghats in Varanasi and Mirzapur districts, forts and fortresses, bridges, roads, tunnels, educational institutions gardens, and places of public utility. The use of this sandstone is evidenced in one of the oldest divine site for Buddhists, the Maha Bodhi Temple Complex (UNESCO World Heritage Site), located in Bodh Gaya. The National Emblem of India is taken from the Lion capital of Ashoka in Sarnath and is carved from these sandstones. There is historical a record of about 285 old quarries in and around Chunar area, where these rocks are well exposed. Kaimur Sandstone fulfils the necessary standards for the status of a Global Heritage Stone Resource.