During late July and early August, it takes place a very curious and interesting natural phenomenon in one of the lakes that conform the Natural Monument “Lagunas de Cañada del Hoyo” (Cuenca-Spain) . Numerous tourism and travel blogs talk about this phenomenon. With this post and considering that this week you can see the famous “whitening water” we are going to better understand the chemical phenomenon and other scientific curiosities hidden in this place.
First of all, we would like to recall that many protected areas in Cuenca province aim to preserve and value their geological heritage, as in the case of the Lagunas de Cañado del Hoyo, declared Natural Monument in March 2007 and included in the Natura 2000 Network. They are also named as a site of Geological Interest (IB029)
Lagunas de Cañada del Hoyo are located at the southeast of the Palancares Molar, in the area known as Los Oteros, dolomitic and limestone area developed on Upper Cretaceous.
The Cretaceous period lasted from 145 to 66 million years ago. It was divided into two parts, upper and lower. The Upper Cretaceous lasted from 98 to 66 million years.
This protected area is composed of 7 permanent lakes and 4 torcas, each receives a different names: Cruz o de la Gitana Lagoon, Tejo Lagoon, el Lagunillo del Tejo, de la Parra Lagoon, de la Llana Lagoon, de las Tortugas Lagoon & de las Cadenillas Lagoon. The depth of the lakes ranges from 4 m to 32 m. In addition to their higher landscape and geomorphological values, these lagoons hide authentic limnological treasures. It is a very fragile and unique ecosystem, thus its functioning as its aquatic communities present.
Torcas and sinkholes have been formed as a result of very complex processes of dissolving sedimentary rocks rich in carbonates (dolomite), which caused the collapse of land and conforming these circular structures. The fact that some are filled with water is due to the high groundwater level aquifer associated Guadazaón river and meteoric waters.
¿Torca or Dolina? Torca is a popular term used in the Serrania de Cuenca, is a ground depression closed and it can be included as a type of sinkhole: polygonal or circular shape, abrupt walls, funnel forms filled of blocks. Did you know that there are a total of 34 torcas within the municipal area of Cañada del Hoyo?
Gitana Lke is one of the best known by the stratification of the water, a phenomenon very studied by the scientific community. It is called meromíctic lales and in Spain there are not many who have that category. This lake has layers of water with different physicochemical characteristics that remain very stable for much part of the year, from Spring to Summer, without being mixed with a deeper layer that has almost no oxygen. However in Winter this situation changes and takes place partial mixing of the layers occurs.
Two pictures fo Gitana Lake where you can notice the colour changed.
Why change the bluish-green waters to milky blue almost white? The process of “milky waters” is given for a few days in summer when the water temperature is higher. This phenomenon is caused by the precipitation as white small crystals of calcite that they are previously dissolved in water, due to increases in temperature and photosynthetic activity, which cause a decrease in the solubility of calcium bicarbonate.
¿Pink waters? 10 meters depth, due to the accumulation of iron and carbonate ions, their algae present a reddish hue
As a result of all these processes there is a rich and diverse community of plankton with very rare species even globally. As tectonic interest, apart from its genesis, we distinguish up to three faults in the rocky walls.
There is also an important representation of amphibians and reptiles, being remarkable the presence of the only population of the endangered European pond terrapin (Emys orbicularis) in Cuenca province. According to recent studies is aware of its existence at least since the early twentieth century.
Would you like to learn about this natural area? Then you just have to contact us and we will be happy to show the entire set of Torcas-Sinkholes and Lakes and their paleontological importance. Visit the description of this tour.