Several rivers stream out of the eastern mountains of La Rioja, like the Leza, Jubera, Cidacos, and Alhama rivers. Its valleys, filled with Mediterranean forests, are marked by canyons, rocky grounds, and defiles, where numerous raptor colonies nest. The important natural, cultural, and scenic value of the upper Riojan valleys have earned them the distinction of Biosphere Reserve, awarded by Unesco. These landscapes are covered with forests, rocks and cliffs, where we find historic towns, fossilised dinosaur footprints and interesting archaeological sites.
This area also has water of remarkable quality, both in springs and thermal currents. The orography of this Biosphere Reserve is defined by transitions, from high peaks to lower grounds. Fluvial erosion also left a mark in the limestone surroundings.The Leza gorge, with a 500-meter fall, the rocks of Peña del Jubera and the kermes oak groves of Villarroya, which include beech and Melojo oak trees, are some of the most beautiful features of the reserve. In the river sides we find a great diversity of tree species, although the most numerous are ash trees. In addition, Peñas de Leza and Jubera are Special Bird Protection Areas (ZEPA).
Birdwatchers that are specially attracted to birds of pray will be able to enjoy numerous species of them in the reserve, but will be particularly impressed by the griffon vulture colonies. The crags of Arnedillo (Cidacos Valley), the Fuentestrún ravine (Alhama Valley), and the Arnedillo Vulture Observatory are great spots from where to watch these birds.