Geoparque Mundial UNESCO

Nº26 – Peat Bogs of the Hospital del Obispo

Geoparque Villuercas > Nº26 – Peat Bogs of the Hospital del Obispo


The Hospital del Obispo is located on the CC-20 road between kilometre marks 31 and 33 from Navatrasierra; it can also be reached by following the Camino de los Jerónimos (Route of the Hieronymites) from Navalvillar de Ibor or the Camino Real de Castilla (Royal Route of Castile) to Guadalupe. The peat bogs can be found all along the valley of the Garganta del Hospital over a total surface area not exceeding 6.000 m2. They should not be stepped on or walked on as there is a high risk of sinking into their muddy marshes. Moreover, peat bogs are very vulnerable ecosystems and visitors’ footsteps may disturb the ecological balance.


In this leafy valley we encounter the fountain of the hamlet and the chapel of the Hospital de la Santa Cruz. It was founded in 1504 by Diego de Muros, the bishop of the Canary Islands, as a lodging for the kings and pilgrims bound for the Monasterio de Santa María on the Camino Real from Castile to Guadalupe.

With an ascent of the Risco Carbonero (1428 m) on the track that reaches the fire prevention installations, the visitor can obtain complete geological information on the surroundings with observations of the extensive pedreras, the hill of the Camorro de Navalvillar, and the megastructures of the Guadarranque syncline and the Ibor-Guadalupe anticline.


The Hospital del Obispo is a nava or flat area located at an altitude of 1000 m within the huge Ibor-Guadalupe anticline. It represents a valley raised above other nearby valleys and located on shales between the quartzite elevations of the Sierra del Rullo (Cancho del Ataque) and the Sierra del Hospital (Risco Carbonero).

The nava of the Hospital de Obispo has a gentle longitudinal profile with a less steep topographical slope than that of the other valleys drained by the streams of the area. As drainage is slow owing to this gentle slope, the rainwater floods the clayey and muddy sediments to form small pools known as “bohonales“, “quagmires”, or “trampales” where the peat bogs form.

Peat is an organic non compact material that is rich in carbon and water and that forms owing to the decomposition of plant material, generally mosses, under anaerobic conditions (a very low oxygen concentration). This constitutes an acid environment that excludes the presence of the bacteria and fungi that nitrify more fertile soils. It is for this reason that it becomes mineralised with a high carbon concentration. As this mineralisation process advances the peat slowly darkens from its initial light grey-brown colour and spongy appearance. The process is a slow one; the peat increases in volume but a few millimetres per year. Peat bogs contain materials from thousands of years ago that can be dated.

The vegetation of peat bogs is adapted to the scarcity of nutrients and endemic plant species may be present. In the trampales of the Hospital del Obispo Drosera rotundifolia (popularly known as “Rocío del Sol” or sun dew) can be found. This insectivorous plant makes up for the lack of soil nutrients by its ability to digest small insects that are trapped by the sticky secretions of the hairy leaves.