Orogeny is the mountain-building event. This is caused by plate tectonic processes that squeeze the litosphere together.It may also refer to a specific episode of orogeny during the geologic past. Even though tall mountain peaks from ancient orogenies may erode away, the exposed roots of those ancient mountains show the same orogenic structures that are detected beneath modern mountain ranges.
In classical plate tectonics, plates interact in exactly three different ways: they push together, pull apart or slide past each other in, respectively, convergent, divergent or transform or lateral motion. Orogeny is limited to convergent plate interactions; the counterpart of orogeny for divergent settings is called taphrogeny. The long regions of deformed rocks created by orogenies are called orogenic belts, or orogens.
Orogens can be bent and altered by later events, or severed by plate breakups
Orogenic belts can form from the collision of an oceanic and continental plate or from two continental plates.