Milan M. Radulovic

Abstract: Karst terrains and their specific landforms, such as sinkholes and caves, have been thoroughly studied from the second half of the nineteenth century. However, karst genesis remains a puzzling issue to this day. The results of the recent studies of ocean floor and the results obtained by drilling deep oil boreholes have raised doubts about the existing explanations of the karst landforms development and encouraged the emergence of new views on this subject matter. According to the new hypothesis, the majority of karst landforms were formed at great depths beneath sea level where dissolution of carbonates increases dramatically. Underwater dissolution first caused the formation of karst depressions and the primary network of karst conduits elongated along the existing fractures. This process was followed by further expansion of the conduits and the formation of spacious caves due to the water regression and the action of turbulent flows. It is considered that the introduction of the new concept would accelerate the development of karstology and improve the principles and methods for solving numerous practical problems such as the abstraction of quality drinking water and the research of oil, gas and bauxite deposits.

Abstract: The analysis of the depth of minor karst landforms (karren) created by the dissolution of carbonate rocks by rainwater with the known dissolution rate, provides the answer to the question of how long these rocks have been exposed to atmospheric conditions (1, 2). Carbonate rocks are amongst the most widespread rocks on the Earth. They cover as much as 12 % of the Earth’s land surface. It is believed that most of these rocks have been formed by underwater sedimentation. The most recent concept in karstology presented in the paper "A new view on karst genesis" (2) suggests that most karst landforms (karst depressions–sinkholes, uvalas, poljes; and corrosion karst conduits) have been formed at great depths below the sea level, more precisely below the lysocline (at the depth of approximately 4000 m), where rapid dissolution of carbonate sediments has occurred due to the enormous pressure. Water withdrawal and strong turbulent flows have resulted in the expansion of one part of karst conduits and the formation of vast caves (2). According to this concept, the only karst landforms formed by the solvent action of rainwater (enriched with CO2) are karren. The analysis of the so–called classic karst which exists in the Dinarides (41–45°N, 13–19°E, altitude between 0 and 2,694 m) has revealed that the karren depth in compact carbonate rocks ranges up to 50 cm (2). Data on the dissolution rate of rocks in the same area (3, 4) suggest that the rate of karren deepening can amount to 1 cm per 100 years. Following this data, it can be estimated that the terrains built up of carbonate rocks in the Dinarides could have been exposed to atmospheric conditions just 5,000 years ago. Considering that the average karren depth at different altitudes is rather equal, it can be concluded that both the lowest and the highest point in this area have been exposed to atmospheric conditions for nearly the same amount of time, i.e. the water withdrawal has occurred relatively quickly. Therefore, if macro karst depressions (sinkholes, uvalas and poljes), which can also be found at almost every altitude, have been formed at great depths below the sea level (2), it can be concluded that the entire Earth's surface was covered with water at one point. If the water withdrew just around 5,000 years ago and it occurred relatively quickly, then it is necessary to reconsider the validity of numerous scientific theories or even the validity of the theory of the evolution of living things on the Earth. References: 1. I. Mrak, Minor karst landforms as an indirect method for datation–the case study valley Pod Košuto (Slovenia). Acta Carstologica. 33, 45–59 (2004). 2. M. M. Radulović, A new view on karst genesis. Carbonates Evaporites. doi:10.1007/s13146-012-0125-2 (2013). 3. I. Gams, Factors and dynamics of corrosion of the carbonatic rocks in the Dinaric and Alpine karst of Slovenia (Yugoslavia) (in Slovenian). Geograf. Vesn. 38, 11–68 (1966). 4. I. Gams, Doline morphogenetic processes from global and local viewpoint. Acta Carstologica. 29, 123–138 (2000).