The East Greenland orogen, also known as East Greenland mountain range, is the linear mountain range along the eastern Greenland coast, from 70 to 82 degrees north latitude.
Geologically, the mountain chain consists of late Cryogenian to late Devonian (650 to 350 millions years ago) fold and thrust belts. Little is known about the exact timing and setting of the earlier phases as this area was later heavily deformed during the Caledonian Orogeny (450 to 350 million years ago). The rocks of the East Greenland orogen are mostly Silurian granites with Devonian sedimentary rocks overlying Ediacarian marine deposits, all on a basement of gneisses.
The current mountain range formed as a result of uplift during the opening of the Atlantic Ocean in the Cretaceous and early Tertiary (starting 100 million years ago). The related East Greenland Rift Basin oil deposits are estimated to be one of the largest in the world.