The Kras Region: Basics of Karst Geology in Slovenia

While visiting Slovenia, especially its western part, people often ask why some rocky cliffs are uniquely white and even a bit sharp. Some of them even think that it is chalk by mistake. In this article, let’s dive into the basics of geology and talk about the Slovenian Karst region.

The Karst Plateau is the region in western Slovenia featuring typical for its caves and sinkholes, created by water getting into the reaction with soluble rocks.

However, before reviewing the Karst Plateau itself, let’s get to know what karst is.

Karst: What Is It?

People who thought about chalk when observing karst cliffs were not too far from the truth. On the other hand, to stand on the karst rocks over the edge of the canyon looking down into the water is not dangerous, unless standing on chalk.

Karst is naturally created in the regions of the dissolution of limestone, dolomite, or gypsum. Those are soluble rocks with a high percentage of calcium carbonate, therefore chalk. The limestone is often composed of remains of shells of marine inhabitants. The other two contain magnesium minerals, thereby they came from the insides of the Earth.

As those rocks are soluble, that in simple words, means diffusive in water, this factor creates sinkholes and caves, even complicated drainage systems. Thus, karst caves are one of the main tourist attractions in Slovenia.

Moreover, Slovenian karst influenced the start of studying this phenomenon. It happened back in 1689, when Johann Weikhard von Valvasor, the scientist from Carniola, nowadays the Slovenian region, introduced the phenomenon of the underground river of Lake Cerknica to the Royal Society for Improving Natural Knowledge in London.

It’s interesting to know that Johann Weikhard von Valvasor also studied the highest mountain of Slovenian, the Mount Triglav at that time, that is one of the main symbols of the country nowadays, that appears even on the official coat of arms and the flag of the Republic of Slovenia.

After that karst was studied in the Balkans as well, but by Jovan Cvijić, a Serbian geologist who later became well-known as the “father of karst geomorphology”.

Even the name “karst” appeared in the South Slavic languages earlier than in others. For example, the Slovene form grast was found in official Slovene archives dated back to the 12^th century. However, today in these languages, there are such forms as kras in the Slovene language and krš or kras in Serbian and Croatian. They took it from Romanized Illyrian, and that’s why in Latin it sounds like carsus. Other names came from the Slavic roots, as the first scientists were from these regions, such as Italian carso, German karst, and Albanian karsti. The modern English one entered only in the late 19th century. It was borrowed from the German language.

The Karst Plateau

It is the region that takes place from northeastern Italy to southwestern Slovenia. The region includes the Vipava Valley, the western part of the Brkini Hills, the northern part of Istria, and the Gulf of Trieste.

It is interesting to know that the Karst Plateau is the natural border between Italians and Slovenians. Historically, those ethnic groups were separated by the western edge of the plateau. Moreover, there was firstly named the region and only after that all the karst topography, because of the reasons mentioned above in this article. That is why it is also referred to as the Classical Karst.

On average, the plateau is located at 334 m above sea level. Thus, it gradually descends from the mountains into the water. Technically, it is the continuation of the Učka mountain range that starts in eastern Istria. Because of gradual ascending, this region is less influenced by the Mediterranean climate. This means less humidity but lower average temperatures.

In the old years, the most common tree here was an oak tree. However, it was replaced by the pine trees in the late 19^th and 20^th centuries. Now plateau is covered by vegetation only for one third. The deforestation here started back in the middle ages, for economic reasons. Mainly for local farmers to turn these regions into pastures for sheep.

In Slovenia, the Karst Plateau covers an area of 429 square kilometers, with 19,000 inhabitants living here. There are approximately 100 settlements built on the karst, the most significant of which are Divača, Dutovlje, and Komen. Štanjel.

One of the main touristic centers here is Lipica, with its stud farms. This is the homeland of the well-known Lipizzan horse breed, a noble and elegant horse domesticated many years ago, famous for its adjusting to classical dressage and easy to teach approach. More about it and other endemic fauna of Slovenia, you can check in this article.

The Karst is most known for its caves. In Slovenia, there are Lipica Cave, Divača Cave, Kačna Cave, Postojna Cave, and Vilenica Cave. The last one is the oldest cave opened for tourists in Europe. There is one more, it is called Škocjan Caves, which are included in the list of UNESCO World Heritage Site, hence it is protected by the international convention.

The Karst Plateau is under control of such Slovenian municipalities: Miren-Kostanjevica, Komen, Sežana, Divača, Hrpelje-Kozina.

Karst Living Museum

Despite its name, it is not a building with expositions. Karst Museum is the nature trail, with a footpath and hiking routes, with marked spots of natural, cultural, or technological interest, where visitors can read information and see the “live expo”. It includes all the karst features, and what is why it is Slovenia’s best thematic trail of 2017 and is included in a Natura 2000 site.

The museum lies on 700 hectares (1,700 acres) of the Karst Plateau. There are more than 20 kilometers (12 mi) of walking paths as well as cycling ones here.

This place features sinkholes, uvalas, limestone pavement, chasms, caves, and literally, shows on natural examples how water is drilling soluble corrosion in the limestone using consequences of the chemical action with carbon dioxide and other organic acids. You can observe here the shapes, forms, and patterns created by water. They are rills, karrens, kamenitzas, stone tables, a.k.a. mushrooms, boulders, small and large sinkholes.

The biodiversity is unique here. First of all, it is resistant to shallow soils and the bora. The last one is a specific feature of this region; this is the katabatic wind that blows from the north and northeast in the Adriatic Sea. In this region, the wins can exceed the speed of 200 kilometers per hour!

On the other hand, these conditions are suitable for downy oak, turkey oak, durmast oak, ash, hazel, wild cherry, and field maples. Therefore, forests protect deer, hairs, boars, squirrel, badgers, foxes, wild cats, weasels, jackals, wolves, brown bears, and different birds like owls and woodpeckers from the wind

Also, karst created such a unique environment underground that they appeared to be endemic species there. This means fauna that can be found only here and nowhere else. Those include:

• Acanthocyclops hypogeous is a copepod (plankton) from the family Cyclopidae.
• Anophthalmus hitleri is a species of blind beetles found only in the caves of Slovenia. The name of this one has quite an interesting story. Oscar Scheibel, the scientist who found this species, dedicated it to Adolf Hitler, who had recently become the chancellor of Germany. The Fuhrer noticed that, of course, and sent a letter of gratitude to the scientist. The name, interesting color, and its unusual antennas make this beetle a desire of collector. This led it to the danger of extinction. 
• Fabaeformiscandona aemonae is a species of seed shrimp (plankton) in the Candonidae family.
• Niphargus aberrans is a species of crustacean (shrimps, crabs, lobsters) in the family Niphargidae.
• Niphargus hadzii is also a species of crustacean, named Slovene zoologist Jovan Hadži, in the family Niphargidae.
• Paramorariopsis anae is a species of plankton in the family Canthocamptidae.
• Typhlocypris trigonella is one more species of seed shrimp that is only found in Postojna Cave.

The Hidden Gem of Karst Plateau

The Karst Plateau is a hidden gem of Slovenia. In fact, not for scientists, because it became the place of scientific discovery of the karst. On the other hand, tourists sometimes underrate the value of those rocks.

First of all, it is part of the national culture of Slovenia. At least once, a Slovenian attended caves and felt the wet air with a slight hint of claustrophobia. It is attractive to visitors because caves have their atmosphere of unknown.

On the other hand, the region itself is a compilation of Mediterranean and continental environments. Therefore, weather conditions, flora and fauna, soil, and many other things are mixing, creating an interesting and distinctive place to experience.

The Karst region is also known for its strong red wine produced here, also known as teran. Here, you will find a mixture of Mediterranean and Central European cuisine. For example, only here is produced the special variation of prosciutto, the Karst one.

So, even for Slovenians, this region is full of unique features. They discover it like a new world, so we propose for you to do it!