‘Rare archive’ of early life: Sonbhadra’s ancient fossils vie for UNESCO heritage tag

Officials said that in June 2025 Salkhan Fossil Park was included on UNESCO’s tentative list under the natural heritage category, and that the current fieldwork to document stromatolites is aimed at preparing the technical dossier to support a World Heritage nomination.

Stromatolites are layered, dome-shaped or columnar sedimentary structures formed by microorganisms, primarily cyanobacteria, trapping and binding calcium carbonate precipitates in shallow waters. They are among the oldest evidence of life on Earth, dating back as far as 3.6 billion years, and played a crucial role in creating Earth’s oxygen-rich atmosphere

“The stromatolite field at Salkhan is one of the most clearly exposed and scientifically valuable Proterozoic microbial platforms we have documented in India,” Dr Shilpa Pandey of BSIP’s Centre for Promotion of Geoheritage and Geotourism, who is leading the research team, told The Indian Express. “During our ongoing field work, we have observed well-defined domal, columnar and stratiform structures with laminae that are remarkably intact for their age. This level of preservation allows us to study microbial accretion, vertical growth patterns and sediment trapping processes with far greater clarity than is normally possible at mid-Proterozoic sites.”

Pandey said another striking feature is the density and continuity of the exposures: close to a thousand stromatolite structures occur within a compact outcrop, and unusually they can be mapped directly at the surface without extensive excavation.

“The hosting dolomitic limestone provides a reliable stratigraphic framework and helps us reconstruct the environmental conditions under which these microbial systems developed. Our observations at Salkhan contribute meaningful data on palaeo-water chemistry, depositional settings and early oxygenation processes,” Dr Pandey added, noting that the site offers students and visitors an accessible example of early life systems otherwise preserved only in remote or highly eroded terrains.

Officials said the team, working under the memorandum of understanding (MoU) signed last June between the Uttar Pradesh Eco-Tourism Development Board and BSIP, is also raising awareness among villagers about the scientific value of the outcrops and the need to conserve them as fragile fossil surfaces rather than ordinary rocks.

Under the MoU, BSIP will carry out scientific studies, geoheritage documentation and prepare technical inputs for the UNESCO nomination, while the Tourism Development Board will focus on visitor infrastructure, interpretation and conservation-oriented tourism planning.

As part of the collaboration, BSIP experts are also conducting outreach with students and sensitising local communities about why the rock surfaces deserve protection.

Those layered microbial mats are credited with playing a key role in enriching Earth’s atmosphere with oxygen, making Salkhan “a rare outdoor archive of the Great Oxidation Event,” officials said.

Comparative studies indicate Salkhan predates and rivals better-known stromatolite sites such as Shark Bay in Australia and locations in Yellowstone, strengthening its case for global geoheritage recognition.

“UNESCO documentation notes that Salkhan fits the IUCN geoheritage theme of the evolution of life and the history of planet Earth, categories reserved for sites of outstanding geological significance,” an official said, adding that Salkhan assumes special global importance because Precambrian, and particularly Mesoproterozoic, fossil records are under-represented worldwide.