The Añana Diapir was formed by
evaporites from the
Keuper which ascended through
Jurassic,
Cretaceous and
Tertiary layers. Other types of rocks were carried together with the evaporites, notably
ophites.
Clay,
marl and
gypsum are also present in the diapir.[2] The
hydrogeological system of the diapir is complex. The saline water that flows through the Salt Valley results of the mixing of (at least) two types of water: superficial waters from the eastern part of the diapir and deeper waters from the western part (the ones which make the spring water saline).[3]
In the hypersaline waters of the Salt Valley, the only animals present are Artemia parthenogenetica and Ochthebius notabilis, with more species in areas of lower salinity. Lake Arreo is home to four fish species, and several bird species have been observed in its vicinity.[4][5]
^
abcDiapiro de Añana(PDF). Euskal Mendizale Federazioa (Report) (in Spanish). Sistema de Información de Biodiversidad. pp. 6–9. Retrieved 11 October 2022.