The geographical feature known as sinkhole or, as it is called in English sinkholes , consists of a series of sinkholes, large and impressive holes that can appear in the soil due to the erosive action of water . In cases where they affect cities or roads, they become a real nuisance, as they can cause major disasters. For example, in El Valle del Ebro, in Spain, the appearance of this type of depression is common in urbanized areas, which endangers the life of the neighborhood, road traffic or the integrity of the buildings themselves. But how exactly do sinkholes or sinkholes come to be formed?
In essence, its appearance, which can be related to both natural causes and human action, has to do with water. Commonly, water from heavy rains or that is present due to low sea levels in that area, ends up affecting one of the underlying rock layers of the soil , that is, it manages to modify some of its non-surface layers. When this happens, two things can happen that cause a sinkhole to form.
In the first place, it could happen that under the ground that we step on there is an underground cavern although we do not know it, and that, when erosion affects the roof of it, it collapses and ends up exposing it. In the second case, it may happen that, since there is no cave, the action of the water dissolves the rock that makes the soil hold firmly, also causing it to collapse and thus giving rise to these terrestrial abysses.
In any case, not all soils are equally susceptible to the appearance of sinkholes . In fact, the very term dolina finds its etymological origin in Slovenian , since it is in these regions -especially in the Carso region- where it is more common to find them. This is due to the type of soil they have and which is mainly made up of a series of specific rocks, such as limestone or gypsum , in turn composed of minerals that dissolve when they come into contact with water. This type of relief is known as karst relief and it has left impressive natural landscapes that we can enjoy.
The rock salt around the Dead Sea Sea or the limestone in the Yucatan Peninsula of Mexico, are two other good examples of the natural formation of sinkholes in the world. In Spain, one of its best known and most impressive sets of natural sinkholes is the Torcas del Palancar , located in the province of Cuenca, and which have become an incredible tourist attraction in the Autonomous Community of Castilla-La Mancha.
And it is that in addition, there are many types of sinkhole that can be formed. Sinks , for example, are a class of circular sinkholes that act as drains for rainwater and small river flows; Tollos , very common in the Castilian-Leon geography, are similar to sinkholes, but the water they collect is absorbed very quickly by the type of rock that makes them up.
