A huge group of rigid rocks that are part of the Sierra de Peracalç, in the Catalan Pyrenees, moves laterally in a north direction at a speed that ranges between one and three millimeters a year. Its aboutlargest mass movement described so far in the mountain range, and has been discovered by an international group of researchers, including scientists from the universities of Gerona, Zaragoza, Modena and the Autonomous University of Barcelona.
The displacement occurs because the huge mobile mass, about 4.5 square kilometers in size, is located on a layer of evaporitic rocks that dissolve very easily. As a result, large breaks occur and the dough shifts laterally. According to the researchers, this phenomenon has occurred for at least 45,000 years , and the most active processes take place in the highest part of the Sierra, at 1,400 meters above sea level. There you can see a series of kilometer cracks, also called grabens, with a width that sometimes exceeds one hundred meters. These geoforms have a high heritage value and, according to the researchers: “the Sierra de Peracalç is like a scale model of what is probably the best example in the world of this phenomenon, the Grabens of Canyonlands National Park, in Utah, United States. United”. On the other hand, according to the data collected, the Lake of Montcortès, in the same region, would also have formed as a result of these processes . This is one of the only two lakes in the Pyrenees that do not have glacial origin.
“These hillside movements are important socially and economically, due to the risks that they can entail for the activities and infrastructures of the area, and the excellent aquifers that they originate, since they facilitate the infiltration and circulation of underground water”, explained Rogelio Linares, a participant in the study that has been published in the journal Lithosphere .
