New Delhi, July 1 -- Presumed ancient carvings on quartzite rocks in Delhi's Central Ridge, near the Delhi Polo Club, have been discovered by environmentalists, marking the first likely record of a petroglyph in the Central Ridge, experts said. Similar rock carvings have previously been documented around the Jawaharlal Nehru University (JNU) campus, while prehistoric stone tools have been found near the Kamla Nehru Ridge. Experts said neighbouring Bhondsi, Surajkund, Mohabatabad, Dhauj, Kot and Alwar have also yielded similar engravings and stone tools. Environmentalist Pradip Krishen, who made the discovery with environmentalist Chetan Agarwal, said he noticed the carvings during a walk last week. "We (Chetan and I) happened to notice this...