Topography ofCroatia is defined through three majorgeomorphological parts of the country. Those are thePannonian Basin, theDinaric Alps, and theAdriatic Basin. The largest part of Croatia consists of lowlands, with elevations of less than 200 metres (660 feet) above sea level recorded in 53.42% of the country. Bulk of the lowlands are found in the northern regions of the country, especially inSlavonia, itself a part of the Pannonian Basin plain. The plains are interspersed by thehorst andgraben structures, believed to break the Pannonian Sea surface asislands. The greatest concentration of ground at relatively high elevations is found inLika andGorski Kotar areas in the Dinaric Alps, but such areas are found in all regions of Croatia to some extent. The Dinaric Alps contain the highest mountain in Croatia—1,831-metre (6,007 ft)Dinara, as well as all other mountains in Croatia higher than 1,500 metres (4,900 feet). Croatia'sAdriatic Sea mainland coast is 1,777.3 kilometres (1,104.4 miles) long, while its1,246 islands and islets encompass further 4,058 kilometres (2,522 miles) of coastline—the most indented coastline in the Mediterranean.Karst topography makes up about half of Croatia and is especially prominent in the Dinaric Alps, as well as throughout the coastal areas and the islands.
The largest part of Croatia consists of lowlands, with elevations of less than 200 metres (660 feet) above sea level recorded in 53.42% of the country. Bulk of the lowlands are found in the northern regions of the country, especially inSlavonia, representing a part of thePannonian Basin. Territory with elevations of 200 to 500 metres (660 to 1,640 feet) above sea level encompasses 25.61% of Croatia's territory, and the areas between 500 and 1,000 metres (1,600 and 3,300 feet) above sea level cover the 17.11% of the country. Further 3.71% of the land is situated at 1,000 to 1,500 metres (3,300 to 4,900 feet) above sea level, and only 0.15% of Croatia's territory lies at elevations greater than 1,500 metres (4,900 feet) above sea level.[1] The greatest concentration of ground at relatively high elevations is found inLika andGorski Kotar areas in theDinaric Alps, but such areas are found in all regions of Croatia to some extent.[2] The Pannonian Basin and the Dinaric Alps, along with the Adriatic Basin represent majorgeomorphological parts of Croatia.[3]
Croatia'sAdriatic Sea mainland coast is 1,777.3 kilometres (1,104.4 miles) long, while its1,246 islands and islets encompass further 4,058 kilometres (2,522 miles) of coastline. The distance between the extreme points of Croatia's coastline is 526 kilometres (327 miles).[4] The number of islands includes all islands, islets, and rocks of all sizes, including ones emerging at ebb tide only.[5] The islands include the largest ones in the Adriatic—Cres andKrk, each covering 405.78 square kilometres (156.67 square miles), and the tallest—Brač, whose peak reaches 780 metres (2,560 feet) above sea level. The islands include 48permanently inhabited ones, the most populous among them being Krk andKorčula.[1]
The shore is the most indented coastline in the Mediterranean.[6] The majority of the coast is characterised by a karst topography, developed from theAdriatic Carbonate Platform. Karstification there largely began after the final uplift of theDinarides in theOligocene and theMiocene, when carbonate deposits were exposed to atmospheric effects, extending to the level of 120 metres (390 feet) below present sea level, exposed during theLast Glacial Maximum. It is estimated that some karst formations are related to earlier immersions, most notably theMessinian salinity crisis.[7] The largest part of the eastern coast consists ofcarbonate rocks, whileflysch is significantly represented in the Gulf of Trieste coast, on theKvarner Gulf coast opposite Krk, and in Dalmatia north of Split.[8] There are comparably small alluvial areas of the Adriatic coast in Croatia—most notably theNeretva Delta.[9] The westernIstria is gradually subsiding, having sunk about 1.5 metres (4 feet 11 inches) in the past two thousand years.[10] In the Middle Adriatic Basin, there is evidence ofPermian volcanism observed in area ofKomiža on the island ofVis and as volcanic islands ofJabuka andBrusnik.[11]
Formation of theDinaric Alps is linked to a LateJurassic to recentfold and thrust belt, itself a part ofAlpine orogeny, extending southeast from the southernAlps.[12] The Dinaric Alps in Croatia encompass the entireGorski Kotar andLika regions, as well as considerable parts ofDalmatia, with their northeastern edge running from 1,181-metre (3,875 ft)Žumberak toBanovina region, along the Sava River,[13] and their westernmost landforms being 1,272-metre (4,173 ft)Ćićarija and 1,396-metre (4,580 ft)Učka mountains inIstria. The Dinaric Alps contain the highest mountain in Croatia—1,831-metre (6,007 ft)Dinara, as well as all other mountains in Croatia higher than 1,500 metres (4,900 feet)—Biokovo,Velebit,Plješivica,Velika Kapela,Risnjak,Svilaja andSnježnik.[1]
Karst topography makes up about half of Croatia and is especially prominent in the Dinaric Alps.[14] There arenumerous caves in Croatia, 49 of which deeper than 250 metres (820.21 feet), 14 deeper than 500 metres (1,640.42 feet) and three deeper than 1,000 metres (3,280.84 feet).[15] The longest cave in Croatia,Kita Gaćešina, is at the same time the longest cave in the Dinaric Alps at 37,389 metres (122,667 feet).[16]
| Highest mountain peaks of Croatia[1] | |||
|---|---|---|---|
| Mountain | Peak | Elevation | Coordinates |
| Dinara | Dinara | 1,831 m (6,007 ft) | 44°3′N16°23′E / 44.050°N 16.383°E /44.050; 16.383 |
| Biokovo | Sveti Jure | 1,762 m (5,781 ft) | 43°20′N17°03′E / 43.333°N 17.050°E /43.333; 17.050 |
| Velebit | Vaganski vrh | 1,757 m (5,764 ft) | 44°32′N15°14′E / 44.533°N 15.233°E /44.533; 15.233 |
| Plješivica | Ozeblin | 1,657 m (5,436 ft) | 44°47′N15°45′E / 44.783°N 15.750°E /44.783; 15.750 |
| Velika Kapela | Bjelolasica – Kula | 1,533 m (5,030 ft) | 45°16′N14°58′E / 45.267°N 14.967°E /45.267; 14.967 |
| Risnjak | Risnjak | 1,528 m (5,013 ft) | 45°25′N14°45′E / 45.417°N 14.750°E /45.417; 14.750 |
| Svilaja | Svilaja | 1,508 m (4,948 ft) | 43°49′N16°27′E / 43.817°N 16.450°E /43.817; 16.450 |
| Snježnik | Snježnik | 1,506 m (4,941 ft) | 45°26′N14°35′E / 45.433°N 14.583°E /45.433; 14.583 |
ThePannonian Basin took shape throughMiocenian thinning andsubsidence of crust structures formed during LatePaleozoicVariscan orogeny. The Paleozoic andMesozoic structures are visible inPapuk and other Slavonian mountains. The processes also led to formation of astratovolcanic chain in the basin 17 – 12 Mya and intensified subsidence observed until 5 Mya as well asflood basalts about 7.5 Mya. Contemporary uplift of theCarpathian Mountains severed water flow to theBlack Sea andPannonian Sea formed in the basin. Sediment were transported to the basin from uplifting Carpathian and Dinaric mountains, with particularly deep fluvial sediments being deposited in thePleistocene during uplift of theTransdanubian Mountains.[17] Ultimately, up to 3,000 metres (9,800 feet) of the sediment was deposited in the basin, and the sea eventually drained through theIron Gate gorge.[18]
The results of those processes are large plains in the eastern Slavonia,Baranya andSyrmia, as well as in river valleys, especially alongSava,Drava andKupa. The plains are interspersed by thehorst andgraben structures, believed to break the Pannonian Sea surface asislands.[citation needed] The tallest among such landforms are 1,059-metre (3,474 ft)Ivanšćica and 1,035-metre (3,396 ft)Medvednica north ofZagreb and inHrvatsko Zagorje as well as 984-metre (3,228 ft)Psunj and 953-metre (3,127 ft) Papuk which are the tallest among the Slavonian mountains surroundingPožega.[1] Psunj, Papuk and adjacentKrndija consist mostly of Paleozoic rocks which are 350 – 300 million years old.Požeška gora, adjacent to Psunj, consists of much more recentNeogene rocks, but there are also UpperCretaceous sediments andigneous rocks forming the main, 30-kilometre (19 mi)ridge of the hill and representing the largest igneous landform in Croatia. A smaller igneous landform is also present on Papuk, nearVoćin.[19] The two, as well asMoslavačka gora are possible remnants of a volcanic arc related to uplifting of the Dinaric Alps.[12]
