Rock art engravings found in Goa exhibit the earliest traces of human life in India.[12] Goa, situated within the Shimoga-Goa Greenstone Belt in the Western Ghats (an area composed of metavolcanics, iron formations and ferruginous quartzite), yields evidence for Acheulean occupation.[13] Rock art engravings (petroglyphs) are present on laterite platforms and granite boulders in Usgalimal near the west flowing Kushavati river and in Kajur.[14] In Kajur, the rock engravings of animals, tectiforms and other designs in granite have been associated with what is considered to be a megalithic stone circle with a round granite stone in the centre.[15] Petroglyphs, cones, stone-axe, and choppers dating to 10,000 years ago have been found in various locations in Goa, including Kazur, Mauxim, and the Mandovi-Zuari basin.[16] Evidence of Palaeolithic life is visible at Dabolim, Adkon, Shigao, Fatorpa, Arli, Maulinguinim, Diwar, Sanguem, Pilerne, and Aquem-Margaon. Difficulty in carbon dating the laterite rock compounds poses a problem for determining the exact time period.