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 Peņa 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