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Location
The town of Uña is located in the heart of the Serranía de
Cuenca Natural Park, declared in 2007. This protected space
encompasses the most characteristic sectors of the Serranía,
belonging to 11 municipalities. Laguna de Uña is the habitat of
unique aquatic birds such as the little grebe and the common teal.
Among the ichthyofauna species, perch, goby and carp stand out.
But above all, if something stands out in the fauna that we can
see on this itinerary, it will be the birds of prey, especially
the griffon vultures, which will almost certainly fly over us at
some point along the way.
Geological setting
This sector belongs to the Alta Serranía de Cuenca, within the
Iberian Mountains, where sedimentary rocks of calcareous or
carbonatic composition abound, such as limestone and dolomite,
which are mainly formed by calcium carbonate that dissolves very
easily in water. These rocks are distributed in the Uña sector in
two groups: the limestones and marls that were formed on a marine
platform during the Jurassic and the dolomites and sandstones with
carbonate cements that were also formed in the marine environment
during the Cretaceous. Two episodes of geological history in which
Iberia was a large island and Cuenca, along with this sector of
the Serranía, was submerged under the sea. Later, during the
Alpine Orogeny, the mountain ranges of the Iberian Cordillera were
raised due to the collision of the tectonic plates of Africa and
Europe, which crushed the Iberian Peninsula, radically changing
the landscapes. For 15 million years Iberia ceased to be an island
and a large part of the territories that had been under the sea
for millions of years emerged, joining Europe through the
Pyrenees.
Once exposed on the surface, the rocks began to be eroded by rain,
wind, ice and sunshine. The water cycle made its appearance and
infiltrated into the depths of the ground through the fractures
and the gaps that it generated by dissolving the carbonate rocks.
In reality these rocks are like a Gruyere cheese and they are full
of holes and ducts through which the water circulates. These
dissolution processes were more active during the Pliocene and
during the warm periods of the Quaternary, thus forming the
morphologies that we call “karst” type, which are typical of a
humid and temperate climate.
Karst
The word "karst" comes
from Carso/Kras, from the Italian-Slovenian region where
calcareous plateaus with this type of geomorphology abound. The
relief is fundamentally conditioned by the dissolution of rocks
with a carbonate composition, although it also occurs in regions
with evaporitic rocks, such as gypsum. Karstification is one part
of a large cycle that begins with rainwater, which is poorly
mineralized and contains a low amount of carbon dioxide (CO2).
Upon reaching the surface of the earth and crossing the soil,
these waters are loaded with CO2 produced by the biological
activity of plants and bacteria and, subsequently, penetrate deep
into the subsoil.
Calcareous tuff
Calcareous tuff,
travertine, or rough stone, this last term in the field of
industrial rocks, is a very porous limestone rock, a variety of
silt, formed by the precipitation of carbonates from bodies of
fresh water at room temperature, on numerous occasions on live
plants
Rainwater is poorly mineralized and contains a very low amount of
carbon dioxide (CO2). When crossing the ground, these waters are
loaded with CO2 produced by the biological activity of plants and
bacteria, and can dissolve calcareous rocks. Thus, water highly
loaded with CO2 can dissolve the calcareous rocks of the aquifer
during its underground journey. It then takes with it the
dissolved calcium (Ca2+) and carbonate (HCO3-) ions.
When it comes out of the subsoil in springs, waterfalls or rivers,
the water degasses (loses CO2), due to turbulence or due to the
biological action of plants when using CO2 in photosynthesis, and
precipitates calcium carbonate (CaCO3) in the form of calcite
Uña
lagoon
Laguna de Uña is a natural wetland of karst origin that was
artificially regrown at the beginning of the 20th century to
supply the Villalba de la Sierra hydroelectric jump. Originally,
the lagoon was dammed by a tuff barrier that acted as a natural
dam. This barrier was formed by the precipitation of calcium
carbonate dissolved in the water. Layer by layer, the tuff grew,
giving rise to an increasingly larger dam.
It is formed by the closure of a river dam of the
Arroyo del Rincón, a tributary of the Júcar river, forming a
lagoon space. The Arroyo del Rincón reaches the Uña Lagoon
after passing, first, through the Uña common trout fish farm
and then through the Regional River Fishing School in the same
town.
Fuentes:
PASEO GEOLÓGICO POR EL ESCALERÓN Y LA RAYA (UÑA)
Wikipedia
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