Goa is a state on the southwestern coast of India within the region known as the Konkan, the characteristic rugged section of the mid-western coast. It is separated from the Deccan highlands by the Western Ghats. Acheulean petroglyphs found in Goa are the earliest known traces of human life in India. The state is part of the Shimoga-Goa Greenstone Belt in the Western Ghats, which is composed of metavolcanics, iron formations and ferruginous quartzite. There are no natural caves except for a few small erosional or tectonic caves. However, there are some artificial buddhist caves.