Mountain range of Arcos Nature · Alacón, Andorra-Sierra de Arcos, Teruel Sierra de Arcos, a mountain range that gives its name to the Teruel comarca of Andorra-Sierra de Arcos and forms part of the northernmost alignments of the Sistema Ibérico, in the Albalate del Arzobispo sector (Teruel). It culminates at the Cucutas peak, at about 987 metres of altitude, and consists of a mass of Jurassic limestones folded into an asymmetric anticline oriented northwest-southeast. The río Martín cuts through it in a narrow gorge between the towns of Ariño and Albalate del Arzobispo, widening only where it meets less resistant outcrops of marls and Triassic gypsum. On its southern slope, lignite deposits of Cretaceous origin are worked. Photo: Clemens Schmillen (CC BY-SA 4.0) What to see and do in Alacón