The geology of Odisha is complex and varied. The state is home to some of the oldest rock formations on the planet.The second oldest rocks on the planet were found in Champua, Kendujhar which are 4.2 billion years old. Odisha is part of two cratonic blocks called North Orissa Craton (NOC) and the West Orissa Craton (WOC). There is a third block called the Eastern Ghats Granulite Belt (EGB). It has been considered as a ‘mobile belt' during the middle Proterozoic Era. These formations are separated from each other by deep-seated regional fault boundaries. The fault boundaries are called the north Orissa boundary fault (NOBF) (running along Mahanadi Valley - also called the 'Mahanadi Rift') and the west Orissa boundary fault (WOBF).