The formation of karst craters. The most impressive karst craters
One of the most unusual landforms are karst craters. These incredible formations arise due to the movement of soil in water-soluble rocks. In nature, there is a huge variety of karst craters, which will be discussed in this article.
Simply put, karst craters are formed by dissolving and leaching underground rock formations. As a result, the earth sags, and funnels of various sizes are formed: some do not exceed one meter, others go into the depths of hundreds of meters.
General information about karst processes
A rather serious obstacle is the occurrence of karst craters in any locality. This is especially difficult in construction and the use of technical facilities.In connection with the foregoing, the study of karst is an important, and sometimes the decisive element of engineering geological research, especially in the construction of hydraulic structures.
There are some cases where lakes and entire rivers disappeared from the surface of the earth when large karst formations occur.
The word "karst" historically originated from the name of a plateau in Slovenia, in the region of Trieste, which is a limestone.
Karst craters in Russia are also quite widespread. They can be found on the Russian Plain, in the Urals, in the Angara region, in the Far East and in the Caucasus.
Water-soluble rocks include limestone, chalk, dolomite, marl, very limestone, salt, gypsum, etc.
In the course of construction work, the occurrence of such a natural formation (karst funnel) must be taken into account. The calculation of dimensions (diameter, depth, etc.) is very important when designing any work on such areas. Above all, in the process of selecting a site for construction and for creating safe design solutions for the construction of foundations, an important point is also the degree of activity of these processes.With active karst, the degree of karstness grows, while passive karst developed sometime in the past. Therefore, in the latter there is no any intensive and free movement of water, and it also contains products of removal of other rocks.
Usually they speak of salt karst (chloride - voids in salt deposits), gypsum (sulphate - karst in gypsum) and carbonate (in limestone, chalk, dolomite or marble).
On the earth's surface, karst acquires a variety of outlines — crevices (in geology — punctures), grooves, and grooves. If such karst are common on large areas, they are called carrot fields.
In nature, there are various forms of karst voids.
1. Karst craters - the most common karst manifestations. In the diameter of the size of such funnels - from 1 to 50 meters (there are 100 meters). Their depth varies from 1 to 20 meters. Differ and superficial funnels differ. Failures result from the collapse of subterranean voids in the rocks. Surface are formed as a result of dissolution by atmospheric waters.
2.Panorams - deep karstic cracks leading to surface (atmospheric) water in underground basins.
3The type of the karst funnel polya occurs when combining several karst funnels or when lowering large areas of the earth's surface. The length of this type of karst reaches several kilometers, and the depth - a few meters.
4. Caverns are formed as a result of the dissolution of rocks in the place of numerous cracks.
5. Caves arise as a result of erosion processes, rock caving, dissolution, mechanical suffusion. Dimensions can be huge in diameter and in length reach several tens of kilometers.
Below are some of the most impressive funnels in the world.
The largest karst funnel
Xiaozhai Tianken (another name is Heavenly Pit) is the deepest karst crater in the world in China. Its depth is 660 m, width - 530. This unique place is one of the most popular among tourists. It is especially interesting to visit it during the rainy seasons, due to the fact that during this period amazing waterfalls flow from the edges of this incredibly large funnel.
For a better idea of the scale of this natural pit, it is often compared to the Boeing 747.
Blue hole dina
The types of karst craters are the most diverse in nature. The deepest sea crater (202 meters) is the Blue Hole (almost 2 times deeper than other blue holes in the Caribbean formed in the limestone cavity). It is located in the Bahamas.
An almost round hole in its shape on the surface has a diameter of about 25-35 meters. From a depth of 20 meters it expands markedly, forming a cave with a diameter of one hundred meters.
In general, there are several similar water-filled karst pits. Among them are the deeper ones: Zakaton in Mexico (335 m) and Pozzo del Merro (392 meters) in Italy. But Dina’s Blue Hole is the deepest of all known karst cavities filled with water, with entrances below the ur level. seas.
Sima Humboldt, Venezuela
This is the most unique karst funnel. Its depth reaches 320 meters. But its peculiarity is that the walls of Sima Humboldt are practically vertical, and therefore a special ecosystem has formed within this karst formation.
Unusual plants grow there and unique animals live that you cannot find anywhere else.
The funnel, which bears another rather scary name (“Gates of Hell”), is about 60 meters in diameter, and its depth is approximately equal to 30 meters.
Natural gas comes out of it, which geologists set on fire in 1971 in the hope that it would burn for several days. But the flame still comes out of this burning karst, whose tongues of fire are drawn to a height of up to 10-15 meters.
In conclusion, a little about the karst craters of Russia
There are karst around the world. And Russia is no exception, especially the territory of its middle zone. There are quite a few depressions and karst failures in the Nizhny Novgorod and Vladimir regions along the banks of the Oka River. Huge craters are observed in Dzerzhinsk, in the villages of Pivovarovo, Chud and Monakovo. The city of Vorsma has a large Varsmen karst basin.
In the spring of 2013, three houses went underground in Buturlino (working village). The diameter of the funnel from that time increased from 40 meters to 85. Its depth is 14 meters.
There is a karst lake in the Nizhny Novgorod region, called the Great Holy. According to the existing legend, on the place of this natural reservoir a village with a monastery long ago was located. They went underground, and this place was flooded with water.