{"id":6336,"date":"2026-05-12T13:10:54","date_gmt":"2026-05-12T11:10:54","guid":{"rendered":"https:\/\/laboratorio.geolag.com\/geology-of-oviedo-subsoil-water-minerals-and-heritage\/"},"modified":"2026-06-26T16:15:42","modified_gmt":"2026-06-26T14:15:42","slug":"geology-of-oviedo-subsoil-water-minerals-and-heritage","status":"publish","type":"post","link":"https:\/\/geolag.com\/en\/geology-of-oviedo-subsoil-water-minerals-and-heritage\/","title":{"rendered":"Geology of Oviedo: Subsoil, Water, Minerals, and Heritage"},"content":{"rendered":"\n

The central region of Asturias, where the municipality of Oviedo is located, contains a wide variety of rocks that are part of the La Sobia-Aramo Unit<\/strong>. These are Paleozoic rocks overlain by the Mesozoic-Tertiary Cover in a discordant manner. <\/p>\n\n

\"Geological<\/a><\/figure>\n\n

THE UNDERGROUND OF OVIEDO<\/h2>\n\n

The oldest rocks found in the municipality of Oviedo date from the Ordovician, represented by the Barrios Quartzite, which in the San Andr\u00e9s de Trubia area is folded into a large anticline. Remember that an anticline is a fold in which the oldest rocks are at the core. <\/p>\n\n

Interestingly, in our municipality, the oldest rocks\u2014the Paleozoic ones\u2014are the ones that form the main landforms, such as the Naranco or the Aramo, while the more recent ones form low-lying areas such as the one on which the city of Oviedo is situated (Oviedo, San Claudio, Colloto, Santa Marina de Piedramuelle, and La Manjoya).<\/p>\n\n

Construction Issues<\/strong><\/p>\n\n

Oviedo\u2019s subsoil consists of a wide variety of rocks with low cohesion and numerous faults that cause the materials to be stepped, which, combined with the presence of aquifers, makes it difficult to support underground structures (parking garages, tunnels, etc.). Groundwater often seeps to the surface, making construction techniques complex and driving up the final cost of the projects. The best area to build in Oviedo is the old town\u2026 M\u00e1ximo and Fromestano didn\u2019t know a thing\u2026<\/p>\n\n

WATER IN OVIEDO<\/h2>\n\n

Although Oviedo\u2019s subsoil is rich in aquifers, the city\u2019s water supply relied on springs flowing from nearby areas, such as those at San Esteban de las Cruces and Fitoria. Thus, in 812, the will of Alfonso II the Chaste mentions an aqueduct that carried water from San Esteban de las Cruces to Oviedo. The Foncalada fountain was part of a large hydraulic complex that regulated irrigation in the Santullano floodplains. Similarly, in 1570, construction began on the Los Arcos aqueduct (41 pillars), approximately 400 m long and 10 m high, which would carry water to Oviedo from the Naranco, drawing on the Fitoria spring. <\/p>\n\n

\"Photo
Garnier’s flight over Oviedo in 1911, showing the Los Pilares aqueduct, of which only five arches remain today. IDEA Archive. <\/figcaption><\/figure>\n\n

Font\u00e1n Pond:<\/em><\/strong> There used to be a pond in the area where Oviedo\u2019s market stands today, until 1523, when every resident was asked to bring a cauldron filled with fill dirt to pour into the pond. Little by little, it was filled in to prevent health hazards. Today, the Font\u00e1n fountain itself marks the original ground level. <\/p>\n\n

Torollo Pond:<\/em><\/strong> The mining of Cretaceous clay in the San Claudio area to make roof tiles and bricks has resulted in the creation of a very unique and rare habitat in our municipality. It is a semi-artificial pond about 80 m in diameter that was formed in the mid-1960s. It is home to 86 species of birds\u2014including nightingales, goldfinches, and robins, as well as herons, sparrowhawks, and owls\u2014along with an interesting variety of insects, including species of Community interest, and amphibians. El Torollu is a marshy alder grove and, as such, a habitat of Community Interest. There used to be an old washing place and a spring here where women would come, but everything was lost amid the rubble. Although a request was made to include it in the Network of Protected Areas as a Natural Monument, the request was denied. <\/p>\n\n

Hot Springs:<\/em><\/strong> In Las Caldas de Priorio, the spa was built in 1776 and served as a summer resort for the bourgeoisie in the 18th century. Its waters, at 43\u00b0C, have a concentration of radioactive elements higher than permitted levels (which is normal for this type of hot spring). It appears that this concentration decreases within 20 days. <\/p>\n\n

Caves:<\/em><\/strong> The action of water inside the limestone formations in the municipality of Oviedo has carved out hundreds of kilometers of passages. There are more than 30 caves, almost all of which are located in Carboniferous limestone. Some of them contain cave paintings and other prehistoric art, while others have yielded fossil remains of animals such as a proboscidean (a type of elephant), horses, various types of goats, wild boars, bears, deer, and a steppe bison. <\/p>\n\n

OVIEDO MINERALS<\/h2>\n\n

There are three main minerals that have been mined since ancient times in the municipality of Oviedo:<\/p>\n\n