Orjen


Orjen is a transboundary Dinaric Mediterranean limestone mountain range, located between southernmost Bosnia and Herzegovina and southwestern Montenegro.
Its highest peak is Veliki kabao, which stands at. The Orjen Peak is the highest peak in the Sub-Adriatic Dinarides. The massif of Orjen lies east to south-east of Trebinje in Bosnia and Herzegovina and north-west of Risan in Bay of Kotor. From the town of Risan, situated at the innermost protected part of the bay, a well-engineered road, at first metalled, with many hairpin bends climbs to about 1600 m, over to the interior. At the main summit of Orjen and the surrounding ridges and high plateaus the action of quaternary glaciation is evident. During the Ice Age, long valley glaciers receded from Orjen to the Bay of Kotor and surrounding poljes. Hollowing U-shaped valleys and cirques in their course. Glaciers also shaped jagged peaks and ridges. Glacial and karst type relief combine now in a unique coastal scenery. There are few places elsewhere in the Mediterranean which demonstrate similar phenomena.
The Natural and Culturo-Historical Region of Kotor is a UNESCO World Heritage site, comprising the territory between Orjen and Lovćen, including all the small towns in the bays of Risan and Kotor with their natural setting. With this privileged natural harbour the Bay of Kotor has been settled for millennia. Illyrians and Greeks colonised the coast from 400 BC and established today's ports Risan and Kotor. Due to lack of potable water, the high mountain was never densely populated. Snow patches collected from deep pit holes were used even late in the 20th century to provide the few hamlets with water. Today, wells are used instead.

Geography

Mount Orjen is a block mountain lifted up as a horst and thus towering above the lowered Bay of Kotor and the high karst plateaux surrounding the Mount Orjen horst. With 1895 m difference between the lowest and the highest point, relief energy has a great role in the extremely harsh environment. A hyperkarstic barren landscape of vast karren fields contrasts with very species rich vegetation types, ranging from evergreen deciduous forests at lower altitudes to endemic calcareous Dinaric Fir and Pine forests in higher altitudes. Precipitation reaches 5000 L per m2, amounts typical for tropical rainforests or the eastern Himalayas than the dry Mediterranean. Lying at Europe's wettest coast, snow easily accumulates on karstic plateaux and as late as June small snow patches continue to lie in shaded places under the summits. Skiing is possible but no relevant infrastructures exist today. Orjen is a more important hiking destination. Three mountain huts provide basic accommodation.
Orjen comprises transboundary area of about 400 km2 between Bosnia and Herzegovina and Montenegro, and runs for 25 km from region around Trebinje in Bosnia and Herzegovina in the north-west, to Bay of Kotor in Montenegro in the south-east. Mount Orjen is composed of four high karstic plateaux divided by ridges. Three near parallel ridges collide in Veliki kabao, Orjens' culmination point. The ridges are arranged by elevation with the highest to the north screening the Bijela gora plateaux from the Mediterranean coast. The separated plateaux are the Krivošije to the East, Bijela gora to the North, and Dobri do and Vrbanj to the West. Only few settlements are scattered in surrounding poljes. The poljes of Grahovo, Dragalj, Vrbanj, Krusevica and Grabalj are important for agricultural use and provide the only lines of communication in the karst. Migration circled around Mount Orjen as a major obstacle between the coastal, Herceg Novi and Risan and the interior towns of Grahovo, Trebinje and Nikšić.
Several dry river valleys are found on Orjen. Only in decades they react as short-living rivers when heavy rain and snow-melt combine. Flooding can be a problem and several poljes are renowned for their long inundation periods.

Glacial traces

Mediterranean mountains bear no glaciers any more except small snow fields in some shaded cirques of the Taurus range. Even during the pleistocene snowlines were not much lower as in today's Alps. Glaciers were only of local significance in the Mediterranean enabling frost sensitive vegetation types to survive the climate changes of the Quaternary.
Among the once glaciated Mediterranean mountains Orjen was outstanding for one of the biggest ice cap in the region. A 150 km2 covered 1/3 of the area. All part above 900 m were buried under a thick sheet of ice from where several glacial tongues descended to 500 m above sea level. Traces of glacial activity are evident in any part of Orjen as in the Bijela gora plateaux. No glacial lakes survive today as they were extinguished due to the porosity of the karstified landscape.
Many cirques, U-shaped valleys and moraines and jagged ridges and summits bear the evidence of the glacial erosion.
In Stone Age and Bronze Age humans settled in the Orjen region. This early human activity is depicted by rock paintings of deerhunt and humans in Lipci rock art in Risan bay. A major Bronze Age excavation site is at Popovo polje to the north of Mount Orjen.

Karst

Mount Orjen is built up from pure Cretaceous limestone. As precipitation and temperatures are high and vegetation is abundant karstification processes are evolved. Lapies, sinkholes and caves resolve from the solution of the limestone. The solution process is the faster the more water is available for solution. Vegetation and soilformation play also a role in the process.
A major disadvantage is that the water is percolating fast in the porous rocks and does not form brooks and rivers despite the heavy amounts of precipitation. An overall dryness is characteristic that is unsuitable for settling.
Thus the region has been depopulated for a long time. Only during times of repression the unfavourable high mountains were mainly populated by Montenegrin tribes. During the time of the Ottoman rule from the 15th to the 19th century the high karst was acting as main shelter for the Christian population. Military campaigns of Ottomans and Austro-Hungarians faced heavy losses while both great powers underestimated the difficulties to undertake successful raids in karst areas. The Battle of Vučji Do between Montenegrins and Turks and the Krivošije uprising in 1869 showed that the Montenegrins used the natural conditions in their favour.
Karst is also a major tourist attraction as caves are frequent and peculiar geomorphological forms can be studied. Karst vegetation on the other hand is species rich and major karst areas are hot spots of biodiversity. The both famous Southeast Asian karst areas like the Guilin tower karst region in Southern China or Phuket island in Thailand and the Mediterranean dinaric karst areas with the Plitvice lakes in Croatia and the Bay of Kotor in Montenegro rival with spectacularity.

Geology

Tectonically the area of the Southern Adriatic is very active as the frequency of earthquakes indicates. As the Adriatic Plate subduces under the Dinarides, earthquakes can have devastating energy. Sometimes even tsunamis are observed. Mount Orjen is completely built of folded Cretaceous limestones which belongs to the High-Karst Zone geological unit.
The High-Karst Zone has the greatest extent in the territory of Montenegro. The terrain of this geotectonic unit is mainly built up of Mesozoic limestones and dolomites of several kilometres of thickness. This thickness is even larger, due to the reverse faulting and overthrusting and thus repeating of carbonate series. The karst of this region is characterised by all surface occurrences and all processes characteristic for holokarst such as: karst plain, polje, uvala, sinkhole, dry-, hanging-, blind- and karstified valley, lapies, canyon, shaft, cave, resurgence, vrulja, estavelle and so on.
The karstification of limestones and dolomites in this area is below the base level of erosion, below the sea level and is deeper than 1,000 m. The High-Karst Zone has all the prominent characteristics of fluvial erosion, glacial erosion, lacustrine, sea and combined erosion.
Along the internal belt of Bay of Kotor, from Morinj, across Risan to Kotor, the High-Karst Zone is in direct contact with the sea, as the High-Karst Zone overthrusts the Pindus Cukali Zone where Mount Orjen rises from the Bay of Risan. The direct contact of the Adriatic Sea and the High-Karst Zone leads to interesting hydrological phenomena. In these terrains the largest vrulja on the Adriatic coast, called Sopot, is located. The vast differences in water-yielding capacity of the constant and periodic karst springs point out to the strong karstification of High-Karst Zone limestones and dolomites on Mount Orjen. The difference between minimal and maximal water yielding capacity is over 350 m³.

Climate

Orjen is within the Mediterranean subtropical belt. While summers are hot and sunny, autumn, winter and spring are rainy seasons. It is the climate type of the Mediterranean but modifications exist in the vast region. For example, sinkholes may create local areas with continental microclimates as is the cas with the Borovi do and Opuvani do, where frequent freeze-thaw cycles create favourable conditions for arcto-alpine and alpine biota. A peculiarity of the littoral Dinarides is the precipitation regime as Orjen receives Europe's' most heavy precipitation. Like the monsoon rain is seasonally distributed, thus November thunderstorms sometimes pour 2000 L of water in several days, while August is frequently completely dry leading to forest fires. With a maximum discharge of 200 m³/s water one of the biggest karst springs, the Sopot spring, is a remarkable indicator of this seasonality. Most of the time it is inactive but after heavy rain a remarkable waterfall appears 20 m above the Bay of Kotor.
StationHeight TypeCharacterPrecipitation Snow
Veliki kabao1895Dfscperhumid Mediterranean snowclimateabout 6250ap. 140 days
Crkvice940Cfsb, perhumid Mediterranean mountain climate492670 days
Risan0Csa, perhumid Mediterranean coast climate35002 days

*
classification scheme after Köppen
Two wind systems are noteworthy for their ecological significance: Bora and Sirocco. Strong cold downslope winds of Bora type appear in winter and are most severe in the Bay of Risan. Gusts reach 250 km/h and can lead to a significant fall of temperatures in several hours with freezing events problematic for most of the Mediterranean cultures. Bora weather situations are frequent and sailors keep an eye on the mountains as cap clouds indicate an imminent Bora event.
Sirocco is a warm humid rain and is important as it brings heavy rain. It appears throughout the year but is usually centered in autumn and spring.
StationPeriodHeight IIIIIIIVVVIVIIVIIIIXXXIXIII-XII
Herceg Novi1961–1984402302211831351307328451601813262621974
Risan1961–198440405342340235153101661231882954234343105
Grahovo1961–198471035132430525114294551032024165084733224
Podvrsnik1961–1984630407398367305151101771322384655935863820
Vrbanj1961–19841010472390388321181104701222243695655363742
Knežlaz1961–1984620547472473373207120721362684006296614358
Crkvice1961–1984940610499503398198135821552955027146834774
Ivanova Korita1960–198413504344607424721281987446943006949724614
Goli vrh1893–1913131127128630722618814875702154734153273129
Jankov vrh1890–1909101742438638934621212455582024845795013750
Cetinje1961–198465543435736728816492721182093064894983394
Grab-Zupci1934–19606773333252571951838359861733604474852985
Trebinje1931–19602761931901601021197043761102392472491762
Dubrovnik1931–1960491471131029279602438971562131861307

*
monthly and yearly precipitation ranges in Dalmatia, Herzegovina and Montenegro