1. a region of the Earth's crust that has undergone mountain-building processes, typically characterized by folded and faulted rock layers.
Usage: technical; geology

Examples

• The Appalachian orogen formed during the collision of continental plates hundreds of millions of years ago.
• Geologists study the structure of ancient orogenies to understand plate tectonics.
• The Alpine orogen extends across southern Europe and into Asia.
• Metamorphic rocks are commonly found within an orogen due to intense heat and pressure.
• The Rocky Mountain orogen was created through a series of mountain-building events during the Mesozoic Era.