Tectonic uplift has created deep canyons, and, during the Quaternary, repeated glaciations carved cirques and large U-shaped valleys.

At elevations up to 1,000–1,700 meters, there are extensive forests of beeches (Fagus sylvatica), Abies alba, pines (Pinus sylvestris), oaks (Quercus subpyrenaica), and a lesser extent of birches (Betula pendula), ashes (Fraxinus excelsior), and willows (Salix angustifolia).

In the high meadows from 1,700 to 3,000 meters, there are numerous endemisms including Borderea pyrenaica, Campanula cochleariifolia, Ramonda myconi, Silene borderei, Androsace cylindrica, Pinguicula longifolia, Petrocoptis crassifolia, etc.

Luciano Briet, Soler i Santaló and Lucas Mallada y Pueyo helped promote the reputation of the region and obtain protected status for it.

On 13 July 1982, it was enlarged to its current 156.08  square kilometres, and its official name was changed to Parque nacional de Ordesa y Monte Perdido.