Located in the region ofAlgarve, along the southern coast of Portugal 150 meters from the homonymous beach, the Benagil cave It is an extraordinary natural wonder that attracts thousands of tourists every year. It is not only a breathtaking landscape, but also a testimony of the force of the processes of erosion naturallike thecoastal erosion and the karstwho have it model during theeras geological.
The coastal area ofAlgarve it is known for the numerous caves natural that dot the Atlantic coast. In the surroundings of the small village of Benagilfor example, are counted over 20 Accessible by sea, and many other smaller ones, often difficult to explore. Curiously, in the past many of these natural cavities were used in the past as refuges And deposits for the goods smugglingsuch as alcohol, tobacco and fabrics illegally introduced to Portugal. Among all these caves, that of Benagil It is undoubtedly the most famous. With his domereaches a height of about 25 meters from the sea level, while the diameter of the base reaches the 40 meters. The most characteristic morphological element is thecircular opening in the vaulta real skylight natural with a diameter of about 10 metersthrough which sunlight illuminates the interior of the cave. At the base there is a small one beach accessible only by sea.
The Benagil cave was formed through the processes of superficial geomorphological modelingin particular thecoastal erosion and the karst. Originally, in fact, in its place there was one steep cliff overlooking the Atlantic Ocean. The incappering rock is composed of limestones, rocks carbonate sedimentary approximately formed 20 million of years ago by the accumulation, compaction and litigation of remains of marine organismswhen the area was submerged by a shallow sea.
Over time, after exposure to the surface, the continuous action of the marine waves that yes they break against the cliff it caused adifferential erosioneroding more quickly the layers of rock more tender Compared to those more resistant. This process initially generated small cavitieswhich have gradually expanded and in -depth under the incessant effect of the wave doors and of theabrasion caused by the impact of sand and pebbles transported by the wave motion and the wind against the rocky walls, finally giving rise to the cave we know today.
Parallel, limestone was affected by phenomena of karsta process in which chemically aggressive waters, coming into contact with the rock, slowly dissolve the calcium carbonate, which passes in solution. This phenomenon is believed to be the main responsible for the formation of the summit opening of the Benagil cave, a real doline karst.
The signs of the erosive action, however, are not limited to the cave and its dome, but are also evident in the presence of Faraglioni And arches natural located in the neighboring area. Faraglioni are isolated rock formations which, once an integral part of the mainland, have been gradually modeled by marine erosion until they become “independent pillars”. The persistent action of the waves on the marine caves, such as that of Benagil, can cause the collapse from the time and lead to the formation of these structures. The natural arches, on the other hand, originate when the coastal erosion digs through a promontory, giving rise to Arcuate openings which testify to the intense geological dynamic of the area.
