Ancares Leoneses UNESCO Biosphere Reserve
It is arranged around an important system of long deep valleys and mountain ranges with convex summits and ridges on a base of Palaeozoic materials of the old Hercynian mountain chain. Quartz, slate and schist have a foliated structure, with micro-fractures, which facilitates differential, fluvial and periglacial erosion processes. The geomorphology of the summits is characterized by a flat erosional surface appreciated in many peaks such as Miravelles peak (1 969 m). The tectonic structure together with an annual rainfall of over 1 500 mm creates the geographic feature known as a watershed between the Navia river (north) and Sil river (south), flowing towards El Bierzo from the different valleys: Ancares, Fornela, Burbia and Valcarce-Balboa.
At the brook and river headwaters we can distinguish the remains of Pleistocene glacial cirques such as the case of Ancares and their morainic structures. Recent sedimentary materials accumulate at the narrow bottom valleys and this enable the development of settlements which grow fodder crops and vegetables.
Biogeographically, the massif is influenced by an Atlantic climate with moderate rainfall, but subject to harsh temperatures because of the height, with harsh winters, longer cold seasons and mild summers.
In this context and linked to the steep slopes, and to the orientation and narrowness of the valleys, it spreads from the high pasture lands to the wide lands of common heathers. We find summer pasturelands below 1 300 m, and as we come down these give way to chestnut and oak trees among the dominant pine trees.
The Ancares Leoneses have an important biodiversity (flora and fauna), typical of the sub-humid Atlantic context. Among them, we can find hollies, sessile oaks and silver birches, Scots pines, different kinds of ericaceae, brooms and shrubs, and among the fauna the capercaillie, the grey partridge, the thrush, the wolf, the red fox, the otter, the wild boar and the roe deer. This magnificent group of natural and human aspects made the site to be listed as a UNESCO Biosphere Reserve.