Over time, the layers are compressed and glued together.Metamorphic rocks are formed from other rocks, igneous or sedimentary, which are heated and compressed underground.Igneous rocks are formed ...

China's Cnooc (OTCPK:CEOHF) said Sunday it discovered the world's largest metamorphic rock oilfield in the deep layers of China's Bohai Sea. The state-owned group said it found an additional 40M ...