The terms orogeny and orogenesis are synonymous for tectonic processes that result in the formation of mountain chains. Orogeny and orogenesis are derived from the Greek words oros, meaning mountain, and geneia, meaning born. Orogeny can also have a time connotation when used in naming periods of intense tectonic activity and mountain building, whilst orogenesis is only used to describe the process. For example, "Grenvillian Orogeny" is used to refer to the period of orogenesis in many parts of the world approximately one billion years ago, synchronous with the collision between Laurentia and Baltica in the Grenville Province of North America. Areas in which mountain building have occurred in the past, although no mountains may remain today, are called orogens or orogenic belts.

Orogeny or orogenesis most commonly involves the collision between two continental lithospheric plates or the collision between a continental plate and an island arc. When...