Danube Virtual Museum

Danube through Serbia – forming from geological aspect

During the Late or Upper Triassic Period 290 million years ago, the withdrawal of the Carpathian sea to the east, from many parts of Eastern Serbia occurred. Between the Dinaric Sea to the west and the Carpathian Sea in the east, a unified area of the Pannonian (comprising the surroundings of Belgrade and the whole Šumadija) and Rodopsko mainland (Eastern Macedonia to the north across the present area of the South Morava River basin, Kopaonik, Goč, Gledić Mountains, Juhor and Crni Vrh/Black Peak) with smaller water basins emerged. However, in the early Jurassic Period, the Carpathian sea again began to penetrate, flooding a wide area between Dobra on the Danube, through the Iron Gate/Đerdap, mountains Miroč and Veliki Greben all the way to Stara Planina and Ruja to the south.

In the whole area shallow-water sediments were created, later forming sandstones, limestone and marls with layers of stone coal. On the coasts of the Lower Jurassic Sea, over time, dead plant matter was deposited, especially in bays and estuaries. Stone coal was formed of these deposits in mines in Vrška Čuka, Dobra on the Danube and in Jerma. Finding plant residues with layers of coal in eastern Serbia, points to the proximity of the land and the presence forests prevailing with ferns and conifer.

During the Middle Jurassic, calcareous sediments were created in the deepest parts of the sea. They were about 60 cm thick and were discovered at Cape Greben on the Danube in Donji Milanovac, and are rich in ammonites (Lytoceras, Bulatimorphites, Macrocephalites, Perisphenictes, Oxycerites, Siemiradzkia, Phylloceras etc). It is rare to trace such a succession of communities of ammonites, and exactly this complete stratigraphy makes it a unique site in Southeastern Europe. There is a much greater distribution and thickness, around 600 m, of grey and whitish limestone, formed in the shallow parts on high ridges. They were formed from dead animals, such as corals, ammonite snails (Pleurotomaria), shellfish (Pholadomya, Pecten), hydrozoa (Ellipsactinia) and other organisms formed on cays. Fossil remains of extinct organisms can be found today in many areas of eastern Serbia - almost all the whole area of the Iron Gate/Đerdap was made of them, as well as the banks of the Dunava, on Mount Miroč, Vrška Čuka, etc.

During the Cretaceous period, which lasted nearly 90 million years, a great part of Eastern Serbia was under the Carpathian Sea. The deep water zone of the Carpathian Sea was significantly far away from the sea, spreading from Donji Milanovac on the Danube to Stara Mountain.

During the Lower Cretaceous, clay sediments mainly with cephalopod fauna were formed in this area. Fossils of fauna were also found: ammonites (Desmoceras, Procerites, Parkinsonia, Ptychopachiceras, aptyhusi, etc.), Scallops (Chlamys) and belemnita residues, which can be found today in the open sections of the Ridge at Donji Milanovac, in the Golubac area, Boljetin and Ciganije.

The Carpathian Sea covered the whole of Eastern Serbia during the Senonian Period. Some parts of the mainland were rising from the water - islands covered with lush flora, which later formed thick layers of coal now exploited in mines Rtanj, Dobra Sreća and Podvis. In the late Cretaceous, when the Earth's crust was largely shrinking, causing a sudden withdrawal of the sea. Powerful movements caused lifting of the Carpathian mountain range and complete draining of the Carpathian Sea.

In the Paleocene, after the withdrawal of the Carpathian and Dinaric Seas, some smaller lacustrine basins remained, where freshwater sediments were created.

However, in the early Miocene, along with the uplifting of the mountain range, the earth's crust was ruptured in some places and entire complexes were lowered. In this way, many wide areas were, along the deep fissures, lowered forming basins and valleys. Between the Alps, Carpathians and Dinarides a vast Pannonian Basin was located. The lowering of the land between the Alps in the south and the Czech massif, along the Rhone valley formed a firth. Waters from the Mediterranean Sea penetrated the firth and flooded the entire Pannonian Plain, creating a vast sea from today’s Vienna in the west to Turkestan in the east. The Pannonian Sea, along with Tetis, represented only one part of a vast Paratethys. Tertiary deposits of Đerdap were developed in the form of an "oasis": the Golubački Tertiary, freshwater Tertiary of Dobra and marine Tertiary of Donji Milanovac. Sediments of sand, clay, were rich in well-preserved and diverse fauna, such as shells (Arca, Cardita, Pectunculus, Lucina), snails (Conus, Strombus, Volutes, Cerithium) and coral colonies.

The most famous interpretation of the formation of the Danube was given by the scientist Jovan Cvijić: "... Pannonian and Vlach-Pontian Basins were filled with seas. Those seas were separated by low Carpath-Balkan mountain ranges, but several connections existed between them. One of them was a route of today’s Danube flow. The level of the Vlach-Pontic Sea rapidly started to decrease and the water from the upper Pannonian Sea overbrimmed to the lower Vlach Sea forming an island between the two basins. Both seas were gradually turning into lakes while the Đerdap island continued to exist. Before the beginning of the Ice Age, lake systems, smaller individual lakes and marshes were preserved. This is the period when the Danube was formed. It linked a number of lakes in the Pannonian Basin, while in Đerdap/Iron Gate it succeeded the Đerdap island valley and continues to deepen its bed trough of the Ice Age valley up to this day. Throughout that time the Carpathian-Balkan ranges were slowly rising up, and the Danube was, at approximately the same speed, cutting its magnificent gorge.... "

At the end of the Lower Pliocene, the Pannonian Sea Carpathians forever lost its connection to the Black Sea due to the rise of the Carpathians. It is now a vast lake once again that began to decrease gradually, retaining just above the deepest parts of the Pannonian Basin. Mussels and snails that are found in this fresh water, gradually started to adjust to the conditions of the imposed life. The main representatives of this fauna are shells - Limnokardium, Draisenzia, Unio; snails: Melanopsis, Vivipara, Hydrobia and Valensienzia. At this stage, the Danube was formed. The Pannonian Sea was formed thirty million years ago, and finally it drained through the Danube 600 000 years ago.

In the Quaternary, great climate changes occurred causing the Ice Age. Vast snow covered the whole Pannonian Plain, Slavonia and the northern part of Serbia. But, in the eastern regions of Serbia significantly lighter snowfall was noticed, and therefore the absence of real glaciers as well as presence of grey surfaces of low fields and river valleys. Those greyish and greenish surfaces - ravines or deep river valleys sheltered a number of plant and animal species that had lived in our lands before the Ice Age. The species that survived easily were those accustomed to low temperatures even before the Ice Age, such as mammoth, woolly rhinoceros, reindeer, bison, musk ox, moose, ground squirrel, jerboa, etc. The largest rivers of the Pannonian plain did not look like they do today, mostly because they were marshes and swamp where waters of these rivers was flowing before entering the Iron Gate/Đerdap Gorge and running off to the Black Sea.

In the valley of the Danube River, outside the area of glaciers, there were relatively thick alluvial deposits represented by river terraces and different types of sediments of vast alluvial plains. In the area of Belgrade and its immediate surroundings, the Sava and Danube terraces were mostly made of gravel.

In the area of the Iron Gate/Đerdap and Negotinska Krajina, Jovan Cvijić singled out the system of spacious terraces of the Kladovo-Danube part. The river deposits of Smederevo Danube area form alluvial surfaces, terraces and alluvial plains. Findings of the fossil remains of mammoths, bison and other animals indicate that they inhabited the area during the Ice Age.

In the lowlands loess was deposited in the form of loess plateau (Titel, Srem) resulting in the accumulation of dust taken from large distances by the wind. Thanks to numerous trench, wells, brick factories, tunnels and boreholes on the Zemun side, the loess was found in the form of a plateau, while south of the Danube in the form of a slope loess.

The Zemun loess plateau or Bežanijska Kosa ends with steep loess sections (thickness of over 30 m) towards the Danube. In the bottom there are river and lake sediments with clams. For example, in that particular sediment, the fossil clam Corbicula was found, which during the late Middle Pleistocene disappeared from Europe in the Danube and settled in the Caspian Sea. Along the Danube, especially on its steep sides, thick masses of these loess rocks can be seen, for example in Surduk, Novi and Stari Slankamen, Čot, Batajnica, Mišeluk, etc. South of the Danube, in the Danube area of Gročan, Smederevo and Ram, loess sediments overlay old slopes and river terraces. The loess formed plateau of these areas is a typical prairie terrestrial sediment with cavities from the roots of plants, numerous remains of terrestrial gastropods and traces of steppe rodents.

Many of the geological collections of the Natural History Museum in Belgrade were compiled during the research of the Danube. Today, they testify to the origin, evolution, changes and "sense" the future of the largest river of Central and Southeast Europe - the Danube.

(Text: Natural History Museum in Belgrade)