Nature Reserves on the Trnovo Forest Plateau
The Trnovo Forest Plateau makes up the extreme northwest part of the Dinaric Alps; it's a karst area with a diverse terrain dotted with hills and vales, caves, shafts and other typical karst features. Mt. Mali Golak (1495 metres) is the highest peak as it towers over the Vipava Valley. The lush forest and bare peaks make for an area of geological interest that attracts hikers and cyclists. The Trnovo Forest Plateau features two nature reserves.
The first nature reserve is called “Golaki in Smrekova draga” and stretches over an area of bare peaks, which gives shelter to protected plants and various wild animals. The karst sinkhole of Smrekova draga is a typical example of a frost hollow, with an intriguing climate and vegetation inversion.
Meanwhile, the Paradana Nature Reserve features the Big Ice Cave which is a world famous phenomenon due to its textbook vegetation inversion. The cave has massive amounts of ice that used to be harvested and sold to towns and cities, sometimes exported even to faraway Egypt.
The natural monument of Smrečje is another fascinating frost hollow with a distinct vegetation and temperature inversion. This reserve is completely left up to nature and untouched by human intervention.
Wonders of Nature on Gora
The eastern part of the Trnovo Forest Plateau referred to as Gora by the locals is an idyllic place criss-crossed with stone walls that used to delineate properties. Skirting Gora, which offers lofty views of the Vipava Valley all the way to the Adriatic Sea, are many hiking trails that take hikers up to the protected areas and renowned natural sights.
The Otlica Window (Otliško okno) is a natural bridge in the vicinity of the village of Otlica, which was created in the wake of an intense tectonic fault. The twelve metre tall and seven metre wide orifice is the product of weathering and erosion of bedrock. The Otlica Window is a popular hiking destination that rewards you with an outstanding vista through the window down to the valley.
Legend has it that the window in the rock was created when the Devil stumbled because he couldn’t shoulder the load he was wearing. As he fell, his horn cut through the rock, making the hole.
The area of the village of Kovk boasts two protected sites. The Lower Jurassic limestones display rare, beautifully evolved hydrozoa fossils. Directly next to the road is another eye-catching feature: the prominent karren that were carved into the thick strata of Lower Jurassic limestone. This is a typical karst microrelief form.
Large geological shifts that crafted the present-day relief of the Vipava Valley are responsible for contacts of specific rock types displaying varying degrees of permeability, which has resulted in mighty and extraordinary water springs.
The Vipava River does not spring from one source, instead it bubbles up from a branched system of springs. There are seven permanent springs and at least as many temporary ones – together they make up the famous delta-shaped riverhead, a unique phenomena in Europe. The picturesque karst springs with clean drinking water are set on the rocky outskirts of the town of Vipava, giving the town its unmistakable character.
The Hubelj River springs forth from the steep walls of the Trnovo Plateau just above Ajdovščina. When the waters rise, the spring of the torrential Hubelj River looks magnificent. The highest lying spring can create an up to fifty metre tall waterfall which literally drums as the massive volume of water tumbles into the riverbed.
The Lijak Creek is known for the unusual dynamics of its spring which is activated only after heavy rainfall over the plateau. The riverbed is dry most of the year and the dry spring is a natural peculiarity in itself.
Protected Areas on the Nanos Plateau
The upper part of the Vipava Valley is closed off by the Nanos Plateau which is a high karst plateau with precipitous walls that shape the distinct valley rim. The area of the twelve-kilometre-long and up to six-kilometre-wide plateau is typically varied, dotted with vales, sinkholes and domed peaks. The 1313 metre high Suhi vrh is the highest peak on the plateau. The many well-groomed trails rank Nanos among the most popular hills in Slovenia. In recent years it has also become a destination for mountain bikers. The area of the south and west edge of the Nanos Plateau was declared a natural park on account of its many botanic peculiarities and high level of natural conservation.
The South Edge of the Trnovo Plateau
The entire area along the edge of the Trnovo Forest, spanning from Lijak, Črniče to the village of Stomaž, is protected. The steep walls feature fascinating geomorphologic and climate phenomena. The area is also noted for being an important shelter for flora and fauna. The animal fossil sites are especially attractive.
The biggest attraction of this area is the natural bridge of Skozno. It is a breach in the precipitous edge of the Trnovo Forest Plateau lining the Lijak Creek, offering a beautiful view of the Vipava Valley and Friuli. The natural bridge evolved together with the tiny cave beneath the wall in which a loop trail was set up. Uphill of the village of Črniče is another worthwhile sight: a deep canyon with steep and precipitous walls carved out by the Konjščak Creek.
In the Tertiary period a sea covered the present-day Vipava Valley. Hence, the edge of the Vipava Valley and the Vipava Hills are mostly built from tertiary sedimentary rocks such as flysch, various sandstones and limestones. The plateaus higher up display older rocks, but all are teeming with fossils – evidences of life from millions of years ago. Fossils are literally everywhere – in the valley and on the high plateaus. The finest examples of fossilized corals and shells – some of them even world-first discoveries – and other remarkable finds such as a fossilized shark tooth fragment are kept in the unique fossil collection compiled by Stanislav Bavčar, which is on display in the Museum of Ajdovščina.