The Valsain Mountains (Spanish: Montes de Valsaín) are located in the Valsain Valley, on the northern slope of the Sierra de Guadarrama and in the municipality of Real Sitio de San Ildefonso, belonging to the province of Segovia (Castilla y León, Spain).
They are formed by two mountains (called Montes, in Spanish), Pinar and Matas, both of public utility and belonging to the National Parks Autonomous Agency, which manages it through the Centro Montes y Aserradero de Valsaín ("Valsain Mountains and Sawmill Center").
Three areas for recreation and dissemination of natural values have been enabled within its boundaries. These are: Boca de Asno—which has an interpretation center—Los Asientos, and El Robledo. The Centro Nacional de Educación Ambiental (CENEAM) also has its facilities there.
Description
The Valsain Valley is located on the northern slope of the Sierra de Guadarrama crowned by the passes of Navacerrada and La Fuenfría, known as the historical pass of the sierra. The Sierra de Guadarrama covers it on the east side, while the mountain range of La Mujer Muerta covers it on the west. Between them, the valley extends with an orientation from south to north, an average width of 6 km and an approximate length of 9 km. The altitude of the area varies between 1100 masl and the 2125 of Siete Picos. It is crossed by the rivers Eresma, Acebeda, and Peces. The soils are acid based on granite and gneiss.
The surface occupied by the Valsain Mountains is 10 672 ha, of which 7622 are of Monte Pinar and 3046 of Monte Matas, both occupied by different tree species depending on the altitude. Scots pine is predominant and has received the nickname Pino de Valsaín ("Valsain Pine"). It produces excellent wood and has been exploited for a long time, being the economic engine of the valley.
The environmental richness is very high as this is an area of little human activity and historically protected as a reserve and hunting ground by the Spanish monarchy. There is a great diversity of animal species, especially birds and plants.
The valley and the mountains are crossed by the CL-601 regional road that connects Segovia with Madrid through the Navacerrada pass. Another series of asphalted roads and highways (in different states of preservation) cross the area too; they are usually closed to vehicular traffic. Among these roads, the road that crosses the Fuenfría pass stands out, a historic pass through the mountain range that has been adapted over time to the different types of roads, from the mere prehistoric blacksmith road, the Roman road (of which there are important remains) to the asphalted road (whose last version was the road known as Carretera de la República or "Road of the Republic"). This pass has been closed to traffic and replaced by the pass of Navacerrada first and the Alto del León—and the corresponding tunnels—later.
Geology and landscape
Like the rest of the Sistema Central, the materials that form the soil of the valley in which the Valsain Mountains are located are of granite and gneiss origin. They are rigid materials that give the soil an outstanding acidity. These materials were broken following a series of fracture lines that formed the pits and mountain massifs.
The physiognomy of the mountains is structured in three landscape units that are organized depending on altitude, orientation (one is on the sunny side and the other on the shady side), soil, water and prevailing winds, among other factors, where human intervention is one of the most important. These units are: the mountains, the valleys, and the ramps.
Hydrography
The main water courses that run through the Valsain Valley—and with it its mountains—are the rivers Eresma, Acebeda and Peces, all of them in the upper part of their basins. These rivers are formed by the sum of a multitude of small streams that flow down from the mountains surrounding the valley. Annual rainfall usually ranges from 885 mm in the lowlands to 1170 mm in the highlands. It is very often in the form of snow, especially on the summits of the mountains where snow can be seen well into the spring.
The Eresma river is formed by the streams that flow down the northern slopes of Siete Picos, Alto del Telégrafo and Minguete, on its left side and the stream that flows down from Puerto de Cotos.
The Acebeda river is formed by the waters that flow down the slopes of Montón de Trigo and La Pinareja.
The Peces river runs along the eastern edge of the Monte del Pinar.