India, Jan. 5 -- The Aravalli Hills, the oldest fold mountain range in India and among the oldest on Earth, trace their origins to nearly two billion years ago. Once comparable in height to the Himalayas, they now stretch about 700-800 kilometres from Delhi to Gujarat. Often described as the "green lungs of North India," the Aravallis play a vital ecological role-filtering air pollution in the Delhi-NCR, blocking dust from the Thar Desert, slowing desertification, moderating local climate, recharging groundwater (in the lower slope areas), and supporting diverse ecosystems. The range also serves as the source of several important rivers, notably the Sabarmati and the Luni, which sustain wildlife, agriculture, and human settlements in arid...