Pirina polyana

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The Pirina Polyana is the largest trough valley in the Mediterranean area
Pirina polyana

The Pirina poljana (also Dobri do) is a trough valley in the Orjen , a sub-Adriatic high mountains of the southeastern Dinarides in Herzegovina .

Location, relief and geomorphology

The Pirina Polyana is the largest trough valley in the Orjen. It is located northwest of the Zubački kabaos , the main peak of the Orjen. The valley furrow is formed by the two highest ridges of Orjen in Jastrebica and Štirovnik . The approximately 10 km long Talung ( Bosnian poljana ) runs in a north-westerly direction between 900 and 1400 m.

The valley ends in the terminal moraines of the Šljeme , which surround the tongue basin of Ubli. The height of the terminal moraines is 1120 m for the northern wall and 1300 m for the southern wall. Since the tongue basin of Ubli lies at 990–1050 m, the upper edges of the terminal moraines tower over Ubli by 130 to almost 300 m. This makes them the highest known moraine deposits of the Ice Ages in the Mediterranean region. Behind Ubli, the tongue basin narrows to the actual trough valley of Dobri do , which is called Pirina poljana at its end in a smaller tongue basin below the highest peaks of Orjen . On the southwest side it is bounded by a 1200-1300 m high plateau. About this ten are Kare of Stirovnikkamms formed. They extend to the Buganja greda  ( 1835  m. I. J. ). The tongue basin of the Pirina poljana is bordered against the Dobri do by a moraine wall. To the south of the Pirina poljana there are four cirques , below the Vučji zub , a double cirque on the Prasa  ( 1707  m. In the year ) and the large cirque of the Buganja greda. On the northern side are the heavily undercut slopes of Velika Jastrebica, on which there are partly avalanche tracks. Avalanches down to the bottom of the Pirina poljana can occur in snowy years. The valley is characterized by absolute lack of water. The only known springs are on the plateau below the Stirovnik ridge (Studenci). In the past, grazing took place in the oxen, which is still practiced in part over Vrbanj.

To the north of the terminal moraine of the Šljeme there are numerous fluvioglacial deposits that are of considerable size in the rubble cone of Dubrava in Polje von Grab. These deposits were formed by the melting of the ice and the resulting transport of debris from limestone debris.

vegetation

Despite the dry limestone subsoil and its location on the Mediterranean Sea with strongly seasonal seasons due to altitude and high precipitation sums, the valley has a partly Central European vegetation, which is particularly evident in the montane altitude zones. The lower dry and overhanging areas in the tongue basin of Ubli are made up of dry pine forests of the black pine ( Pinus nigra ). This is followed by warmth-loving beech forests with the autumn blue grass ( Sesleria autumnalis ). Mesophytic Dinaric beech primeval forests grow around the tongue basin of the actual Pirina polyana. Park-like open forests of the snake skin pine ( Pinus heldreichii ) dominate above 1450 m . Within these oro-Mediterranean dry pine forests there are already numerous species of Dinaric high mountain vegetation. Above 1700 m this becomes dominant and is represented by the association Oxytropidion dinaricae . Among the rare species, the Orjen Iris and the endemic representatives of the tufted bells should be mentioned in particular . The rock vegetation in the rock Moltkie Moltkia petraea , Neumayer jug fruit ( Amphoricarpos neumaxerii ) and, in particular, Lamiacea of ​​the genera Clinopodium ( Clinopodium thymifolium ), Satureja ( Satureja horvatii ) and Thymus ( Thymus striatati ) is particularly rich in species and endemic species .

Research history

The Quaternary glacial deposits in Orjen were first discovered in 1899 by Albrecht Penck and William Morris Davis on the occasion of an excursion by the Viennese geographers to the karst regions of Herzegovina and Dalmatia. The extremely large dimensions of these moraines were considered a geoscientific "sensation", as they were the first evidence of a larger Pleistocene glaciation in a Dinaric mountain range. Soon after these Penck notes, the geographers Alfred Grund and Ludomir Sawicki began to map the Galcial Traces in Orjen before the beginning of the First World War. After the Second World War, the German high-mountain geographer Carl Rathjens investigated the Quaternary deposits in the poljen and karst plains on the west side of the Orjens. The doctoral theses of the Yugoslav geographers and geologists Josip Riđanović and Miroslav Marković were based in part on this work. Stratigraphic analysis methods for the absolute dating of the terminal moraines in Orjen were published in 2010 by Philp Hughes and in the years thereafter by Kathryn Adamson. Accordingly, the maximum glaciation occurred in the Middle Pleistocene around 350,000 JvH. A total of four icing cycles were found, the last of which occurred in the Younger Dryas .

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  1. ^ Alfred Grund: Contributions to the morphology of the Dinaric Mountains. In: Geographische Abhandlungen edited by Albrecht Penck , Volume IX, Heft 3, 1910, p. 122.
  2. ^ P. Hughes, J. Woodward, P. van Calsteren, L. Thomas, K. Adamson: Pleistocene ice caps on the coastal mountains of the Adriatic Sea. In: Quaternary Science Reviews 29 (27-28), 2010, pp. 3690-3708.
  3. ↑ M. Žebre, U. Stepišnik: Glaciokarstic landforms and processes of the southern Dinaric alps. In: Earth Surfaces and Landforms 40/11, 2015, pp. 1493–1505.
  4. ↑ Bräuchler C. & Cikovac P. 2007: Iris orjenii (Iridaceae) - a new species from the littoral Dinaric Alps. Willdevowia 37: 221-228.
  5. ↑ Albrecht Penckk 1900: The Ice Age traces on the Balkan Peninsula. -Braunschweig: Globus, 78 (9): 161-163
  6. ^ Carl Rathjens 1960: Observations on high-lying poljes in the southern Dinaric Karst. Z. f. Geomorphology, 4 (2): 141-151.
  7. ↑ Adamson, K., Woodward, J., Hughes, P. 2016: Middle Pleistocene glacial outwash in poljes of the Dinaric karst. Geological Society of America, Special Papers, 516, 247-262
  8. ↑ Adamson, K., Woodward, J., Hughes, P., Giglio, F., Del Bianco, F. 2017: Middle Pleistocene glaciation, alluvial fan development and sea-level changes in the Bay of Kotor, Montenegro. In: Quaternary Glaciation in the Mediterranean Mountains, Geological Society Special Publication, Geological Society of London, 198-209.

Coordinates: 42 ° 35 ′ 32.3 "  N , 18 ° 31 ′ 54.9"  E