Structurally these calcareous outcrops are located on the flanks of the great Ibor-Guadalupe anticline, which today has been completely worn down by erosion, in aligned sections of massive appearance but reduced thickness. They are separated from each other in the shape of a rosary; they have generated small projections as a result of differential erosion since these carbonated rocks are harder than the surrounding slates and chalco-schists.
They originate in the organic or biochemical deposits of flat seaweed and stromatolites that were laid down in shallow marine environments of the Ediacaran period (+ 540 m.y.).
Around the quarries the predominant rocks in the valleys are Precambrian shales and greywackes and on the hillsides the limestones, chalco-schists, and shales of the Ediacaran period, while the Armorican quartzites of the early Palaeozoic are situated on the crests where they have been fragmented to form the typical pedreras of the nearby Sierra Palomera.
In the surrounding area we can also observe some layers of conglomerates of quartz boulders and a calcareous matrix with an average thickness of some two metres, which have been worn down by erosion to take the form of large boulders that have become isolated halfway up the slopes.
