Traces of the Pannonian Sea in Belgrade

Looking from Belgrade Fortress towards Srem and Banat, have you ever wondered where the Pannonian Sea disappeared? What happened for such a large body of water to vanish without leaving a trace? Did it really disappear without a trace?! Is it possible that it didn't leave at least a few tangible pieces of evidence that the Belgrade area was once underwater?! Don't trust your eyes. Take a walk through the seaside city of Belgrade and explore the marine landscapes hidden in our capital.

The old residents of Belgrade often had a habit of stopping at Fićir-bajir, a small hill at the most prominent part of the city, while walking through the fortress. From there, you can enjoy a beautiful view of New Belgrade, Zemun, Great War Island, the Sava and Danube rivers. It's hard to resist the monotony of the plain in front of us, which stimulates contemplation. That's probably why the hill is called "Breg za razmišljanje" in Serbian, which translates to "Hill for Thinking." That view often transports my thoughts to the distant past, to the time when the vast and mighty Pannonian Sea existed in that area.

According to books, the Pannonian Sea existed in the Pannonian Basin from 23 million years ago to 1.8 million years ago. It stretched between Vienna in the west, the Slovak Tatras in the north, the Romanian Carpathians in the east, and the Dinarides in the south. At that time, the Danube flowed into the sea near Vienna, the Sava was a short tributary, and the Drina, Kolubara, and Morava rivers were even shorter. The last waters of the Pannonian Sea drained through the Danube towards the Black Sea, and the sea last lapped at Belgrade approximately 8 million years ago. If, by any chance, our capital city had existed at that time, only its highest parts such as Avala, Torlak, and Vračar would have emerged above the water.

The central zone of Belgrade, starting from the Monument to the Victor and extending towards Terazije, Tašmajdan, Slavija, and Čubura, actually represents a large sandbar that forms the backbone of the city today. It was formed in one of the Earth's developmental phases when the area had a warm climate, which favored the development of corals and shells.

The landscape visible from the aforementioned Fićir-bajir represents the bottom of the former Pannonian Sea. Hence the Pannonian Plain north of Belgrade. Of course, over time, the flat expanse has been covered with loess, sand, and fine dust, significantly altering the appearance of the plain.

To see the most obvious trace of the Pannonian Sea in the city center, all you need to do is descend from the Upper to the Lower Town of Belgrade Fortress through Defterdar Gate, heading towards the ruins of the old Metropolitan Palace below the Victor monument. There lies a large Neogene sandbar, which also represents the northern branch of Šumadija. It is composed of sandstone and limestone and has revealed dozens of mollusk fossils, primarily shells, which can be easily spotted with just a cursory glance. The same ridge can be seen in the Belgrade Zoo, and it is these mighty rocks that have prevented the penetration of the Sava and Danube rivers southward.

Let's take a stroll along Karađorđeva Street, from the fortress towards Branko's Bridge. If you pay attention, behind the buildings along the street, you'll have a view of the slope that connects Kosančićev Venac and Karađorđeva Street. That slope is another evidence of the existence of the sea in this area. Namely, beneath the green cover, you can occasionally see the limestone rock from that period, defying the ravages of time. In these soft rocks, several large underground chambers were built in the 19th century, which were used as cellars and warehouses for food and beverages brought by ships to the nearby port at that time.

If we venture a little further, we arrive at Tašmajdan Park. The tall trees and grass are merely a disguise for what lies beneath. We'll descend the stairs towards the courtyard of Peta beogradska gimnazija (Fifth Belgrade Gymnasium). There, another section of the limestone ridge can be seen, next to the pumping station on Aberdareva Street and behind the stands of Tašmajdan Stadium. Today, inside that ridge, there is a famous German bunker from the period of World War II, which was built on the site of a former cave and Roman quarry. It was from this location that stone was extracted for the construction of fortresses and palaces in Roman Belgrade.

Often, limestone rocks from the time of the Pannonian Sea are found just below the asphalt. When excavating foundations for new buildings in the city center, these limestone rocks containing shells, sea snails, and sea urchins are frequently encountered. This happened, for example, during the construction of the Beograđanka building, as well as in buildings on Kosovska, Krunska, and Kumanovska Street. Additionally, along the banks of the unattractive and polluted Topčider River, small isolated sandbars are hidden, filled with snail and shell fossils similar to those found on the Adriatic coast.

There are even more of these traces as we move away from the city center. If we head towards Čukarička padina and Radnička Street, we'll reach the foot of Banovo Hill. Pay attention to the rocks visible behind the buildings. During the existence of the Pannonian Sea, they formed a large sandbar against which the waves crashed. Similar to Karađorđeva Street, numerous underground chambers can be found in these rocks as well.

The exploration doesn't have to end here. We could visit Višnjica, Avala, Sremčica, Cerak, Kneževac... Everywhere we go, if we scratch the surface and remove the green cover, we could touch the bottom or the edge of the former sea.

So, when your path leads you back to Belgrade Fortress, Tašmajdan, Čukarička padina, or Karađorđeva Street, pause for a moment and imagine the vast sea that once existed in these areas. And of course, envision our Belgrade as a coastal town...