Presentation Salt Mine Praid

       The Praid - Basin, the so called “huge salt cellar”, lies at the encounter of the eastern edge of the Transylvanian Basin and the Görgényi Mountains and it constitutes a separate region–unit within the borders of a geographic region called “Sóvidék”.

      The Transylvanian Basin was formed as a result of the continuous sinking that began at the end of the Cretaceous age and the beginning of the Paleocene age while the neighboring Carpathian mountain- chain rose. A shallow continental inland sea was formed in that depression. It wasn’t connected with the surrounding oceans and seas. The continuous sinking of the basin resulted in the forming of a 5000m thick sedimentary stratum, which reveals the paleo-climate conditions of the region and the circumstances in which these strata have settled.

      At the edge of the Transylvanian Basin we can find Paleocene sediments, which lean towards the inside of the basin; further inside we can find the diapire zone, where the deep salt-blocks have broken through the younger sedimentary strata’s. In the center of the basin there is a region of  wide cyclical corrugations – the so called “domes” – that have porous rocks. In the Superior Badenian -, Sarmatic and Lower Pannonian ages significant natural gas - yards came about in these rocks.

      The Transylvanian Basin is vertically divided into three tectonically different parts: a grooved lower part with crystal rocks; the middle part, which is made up by less articulated Senon, Paleogene and Lower Miocene sediments and finally the Upper Baden, Sarmatic and Pannonian sediments that were articulated by salt eruptions and Pliocene movements. The salt strata in Transylvania is found on a surface of 16206 square km and its average thickness is approximately 25m. The salt shows a tendency of moving forward and it lies on the underground Pre-Badenian surface-hills.

      The salt-belt is the most characteristic structural and morphological region of Sóvidék. The salt-belt, that lies along the Szovata-Praid-Korond line represents the edge of the volcanic plain of Mezőhavas (1100-1150m) that was suddenly broken. It lies in the 30km long Praid-Sovata depression between Bekecs Hill (1079m) and Siklódkő (1025m).

      The Praid Basin can be considered a deepened (erosion) basin if we take into consideration its origin. The diaper –tectonic phenomena had an important role in the formation of the basin. This way the appearance of the Sóháta (the salt yard covered the younger strata of the Neogene strata) on the surface modified the accidence and water system of the basin, caused morphological and hydrographic changes. The prominence of salt created a barrier in the way of the Korond river. The Kis-Küküllő, being bigger and more energetic, could keep up with the ascendance of salt body and it could gradually deepen its erosion valley. Probably it had taken along the Stream Korond too for a while through that terrace that lies between Sóháta and Köves-vápa (550m) - to the east.

      In a wider sense the Praid Basin lies round the hill Sóhát, embracing Praid and the two places called Sófalva. The shape of the basin is like a stretched triangle with its peak pointing towards Korond in the south, and to the northwest it reaches Szováta Basin. The Praid Basin is divided from the Transylvanian Basin by the range of Szálas Firtos (1062m), Küsmödkő (991m) and Siklódkő (1025m). The Sóhát (Salt Back), its local name being “Sóháttya”, is in fact holding the most valuable treasure of the Praid Basin and the Szekler Sóvidék (Salt Region): the great salt yard, that has a depth of 2,7 – 3km (root). In horizontal section the salt body has an elliptical shape, its diameters being 1,2 and 1,4km. Vertically it looks like a huge abnormal mushroom. It is due to say that the huge salt block is one of the largest diaper yards in Europe, and its reserve could provide the continent with salt for hundreds of years.

      From the point of view of stratum studies we can say that the salt block, during its ascendance, broke through the younger Mio-Pliocene sediments and came to the surface in the erosion window of the Praid Basin. According to the studies of its structure and strata, we can say that the salt was once down deep under the younger strata’s.

      The material of the salt yard in Praid is the salt rock, the so called “halite” a halogenated mineral, that crystallizes in a rectangular system but sometimes it can have an octahedral shape. The salt in Praid has tiny crystalline granules, but it contains contamination too.

      The “halite” is spread in bulks (initially only the solid mineral was named halite), it is white, it has glass light and it feels oily when touching, it coloures flames into yellow. It can join other types of rocks too in series like: silvine, gypsum, dolomite, anhydrite etc., and its hardness is 2,5 according to the Mohs categorization. The mineral rock that is made up all of halite is named halitite.

      The Transylvanian salt- and within that the salt from Praid- originates in the Lower Baden geological age (the Middle Miocene age) about 20-22 million years ago. At this time the shallow inland sea was blocked and separated from the ancient Tethys, and as a result of strong evaporation the created salt strata settled in the sinking basin. The sediments settled on this salt layer in the following geological ages and due to their pressure the salt moved towards the Transylvanian Basin just like a slowly flowing, thick liquid. Here, in the region of the diaper rucks, the salt layers became solid reacting to great forces and they headed towards the surface in huge blocks of salt. They couldn’t break up to the surface everywhere, they got stuck at different depths and they are still present in the center of salt belts as kryptodiapers.

      In the area of salt mountains we can notice a vivid salt karst phenomena: in the salty areas there are smaller and bigger funnels filled with clay that are similar with the phenomena of limestone areas: dolines, water absorbing blocks, hilite. A number of dolines and blocks are still continuously forming as results of the falling in of some hollows created by underground waters. The bigger funnels are the traces of irregular mining, in certain cases the Roman salt mining in amphitheatre shape or the newer “scamp-mines” (shapeless salt holes), where the people were stealing the salt from in the times when it was banned.

      Sóvidék (Salty Region) and the Praid Basin own many beautiful landscapes, geological and geographical rarities besides the ruling salt and clay (this is where it got its name from: “Szikonyország” = Country of Clay).

      The characteristic flora of Sóvidék has formed very close to the salt rocks. It can also be noticed that as a result of the great amount of evaporation, especially in the summer salt flowers cover the flat parts at it presents a bleak picture of Sohata and Sószoros (Salt Strait). In Sóhomlok, Nádasfő, Fűrészoldal and between the bare cliffs the plants are not totally extinct. To this kind of places characteristic plants are: the thick, red or green Salicornea herbaceaAster tripoliumSpergularia salinaSalsola sodaArtemisia salinaPlantago maritimaStatice gmelini (salt flower).

      60 hacters of Sószoros and Sóhát, and the Csigadomb in Korond were made geological reservations in 1995 (according to law number 13/1995 made by The County Council). The “Salt strait” is in fact a valley created by the Stream Korond and it lies on the southwest part of  the Sóhát (Salt Back). Here the stream cut through the mountain and it flows down surrounded by white salt rocks until its encounter with the Stream Kis-Küküllő. Those salt rocks can be seen in Salt Canyon, and they are called: salt rocks from Praid, and they were a touristic sight in last century too. Here the earth holds the salt-fortune of a whole sea region, the salted water springs are sweating salt and even the dust on the roads is mixed with salt.

      The “Csigadomb” can be found in the southern part of the Praid Basin, next to the road that goes to Korond. The colorful, shiny aragonite rocks were created by the salt spring underneath it that contains lime-tuff. In the slits of the rocks we can sometimes hear the soughing of carbon-dioxid gases. The carbonic sediments of springs are in fact the results of crust-creating characteristics of those spring that contain calcium – carbonate. Aragonite can be found in different colors: white, yellow, greenish blue, grey and black. The aragonite and calcite layers are parallel in the andesitic surroundings and their settlement was partially helped by the lime that the spring water contained and the previously created crusts. Their creation happened in lower temperatures, it can be compared to hydrothermal sediments, which happened in little amounts and in lower temperatures.

      The surroundings of Korond are rich in mineral waters, that contains iron and sulfate, they were also caused by post-volcanic phenomena. For example there are the “fingós” ant the Árcsó springs. The use of these waters represents an interesting fact: the salt baths from Korond are older than those from Szováta. We shouldn’t omit the Pliocene clay sediment at the frontier of Korond. This blue and grey material is used for the famous pottery in Korond. Almost each family has its own clay mine and working techniques.

      We should also mention the material of the surrounding hills (Malom-Mountain, Kopac Mountain, Siklódi Mountain, Bucsin Top, etc.) which surround the Sóvidék with their steep rocky appearance. These mountains were created by Neogene volcanic movements and they form a tongue of the Görgény Mountains. The geomorphology of Sóvidék is made of plains that consist andesite, basalt, dacite and riolite tuff. (Várhegy, The castle of Rapsonné, Kiságkő, Siklódkő etc). Andesite plays an important role in the building material supply of the region (for example the Cserepeskő-“Tiled Stone andesite mine). But of course the most valuable mineral treasure of the region is the hilite, which has linked the lives of those from Praid forever.

      Our geographical survey wouldn’t be complete if we didn’t mention the thermal-water supply which first broke out in 1949 from the study spring number 401 at the feet of the  Harom Mountain. In 1952 a hydro-thermal bath was built to use this water for treatment. That contributed to a greater use of the region’s geological potential. Unfortunately in 1991 it dried up and they had to use the water that leaked in the walls of the salt mine to complete the water of the baths.

      The climate of the Praid Basin is moderate continental, a bit colder than that of the Transylvanian Basin. The average temperature is 8.2 C˚, in the summer 19-20C˚ and in winter –8, -10C˚. The number of days that are warmer than 25C˚ is less than 80, the temperature fluctuation in a year is 60C˚. The warmest month is july, the amount of rainfall is quite considerable: in rainy years 800-1000mm/year, in dry years 600-700/year. The humidity of the air is relatively high, 75-80%.

      We can fairly say that Great Nature was generous to the people of Praid because salt, salted water, mineral water, thermal water, clay-slate, andesit, aragonite and building materials all mean wealth, even if Praid has always been treated as a step child by the Romanian politics of economy.  

                                                                                                                                geol. Horváth István