India, July 2 -- What began as a routine visit to document the biodiversity of Delhi's Central Ridge led two environmentalists to an unexpected discovery, a set of rock carvings etched into a quartzite outcrop near the Polo Ground that experts say require detailed scientific study before their age or significance can be determined.

The carvings were noticed by environmentalists Pradip Krishen and Chetan Agarwal during one of their regular visits to the Ridge, where they usually document the area's rich biodiversity and plant life.

Krishen said the two had visited the spot several times before, but it was during a recent visit that Agarwal noticed unusual markings on a large quartzite rock protruding from the ground near the Polo Ground....