Băile Herculane: Field notes of a geologist in Romania

Marta Pino Larrío (Spain)

In July 2023, I travelled with fellow geologists to Băile Herculane, an ancient Romanian town in the Western Carpathians, situated between the Danube and the Serbian border. Our mission was to analyse the site for a new railway tunnel that will replace the existing one. Băile Herculane, home to approximately 6,000 residents, is renowned for its thermal baths and is one of the oldest spa towns in the world, dating back to 102AD, when it was founded by Emperor Trajan.

The town is located in the Cerna River valley, a tributary of the Danube, which defines the town’s northeast-southwest layout. To the north lies the Domogled-Valea Cernei Nature Park, the second largest natural park in Romania, spanning the counties of Gorj, Caraş-Severin (where Băile Herculane is located), and Mehedinţi. Further northwest, in the Western Carpathians but still in Romania, begins the Great Hungarian Plain, which is geologically part of the Pannonian Basin.

We departed from Bucharest at 7:30am and arrived in Băile Herculane six hours later, having traversed the country on rural roads and through villages with barely a hill in sight, until we reached the Western Carpathians and crossed the Danube.

The landscape was stunning. Despite the oppressive summer heat, the vegetation remained vibrant, surrounded by a variety of wildflowers and shrubs. I identified many plants familiar to Western Europe, including daisies, bluebells, gentians, mallows, thistles, poppies, dandelions, nettles, angelicas, black pines, and rowan trees.

Fig. 1. Dacian Basin geological time scale and International stratigraphic scale, together for comparison. Dacian Basin time scale (4.1 – 8.6 Ma) after Vasiliev et al. (2004) and Krijgsman et al. (2010). The international stratigraphic chart after the International Commission on Stratigraphy (2010). This table was published in Jipa et al. (2011).

After a quick lunch, we drove to the study area near Poarta train station, about 30km northwest of Băile Herculane. This area, slightly longer than the 1,280m, old Poarta tunnel it will replace, proved challenging to survey. The site was dominated by forest and fields, with many roads ending at handmade, sometimes electrified, fences. The geology was obscured, with only sandy and sandy-clay soils visible.

Previous soundings indicated that these soils were from the middle to late Miocene, specifically the Volhynian-Bessarabian stages in Romania (early Sarmatian). The presence of this early Sarmatian has been proved by the fauna found in the Bahna – Orsova and Mehadia depressions (the bivalve molluscs Ervilia podolica, and Abra reflexa, characteristic of the Miocene in this area), while the Middle Sarmantian has only been identified in Mehadia.

Fig. 2. The general landscape of the area.

Fig. 3. The landscape of my working area. On the right is a white wire that was electrified.

Fig. 4. Example of sandy-clay soils on the road.

The next day, we inspected other points along the railway route. We began at the Băile Herculane railway station, known for its art deco architecture and historical significance as a former hunting lodge for Emperor Franz Joseph. Walking along the railway, we encountered Râpa Neagra (Black Ravine), which is a large landslide of dark marly clay, near the Belareca stream, a tributary of the Cerna River. This distinctive landslide consisted of fine, dark grey, almost blue, eroded material.

Fig. 5. The interior of Băile Herculane railway station.

Figs. 6. Râpa Neagra, the blue-grey marl gorge of Mehadia. The size can be appreciated by the people on the right.

After a five-hour walk along the tracks, we reached the Poarta station and tunnel. The station, surrounded by trees and vegetation, appeared isolated and aged. Nearby, a smaller, overgrown tunnel, likely a previous tunnel from 1870 through which the Orient-Express may have passed, was visible.

Fig. 7. Poarta train station. I think the dogs belong to the stationmaster, who was inside.

Fig. 8. The Poarta tunnel – the previous, smaller tunnel, now used as a drain, is on the right, covered by vegetation. It was almost impossible to access it to take a good photograph.

Inside the tunnel, water seeped through the walls, creating limestone deposits and mould due to the moisture from the sandy and clayey ground. This necessitates drainage for the new tunnel to prevent water damage, a problem that afflicted the previous tunnel built in the 1960s.

Fig. 9. The tunnel mouth. Calcareous growth and a lot of mould can be seen in the picture on the right. In other areas of the tunnel, there are also small cracks, although they are not visible here.

After documenting the site, I explored Băile Herculane’s historic center. Once a prominent spa destination, the town retains its nineteenth-century charm, despite many buildings needing restoration. Notable sites include the Neptune Baths, Apollo spa (now a museum), the Casino, and a house once belonging to Empress Sissi of Austria-Hungary.

Fig. 10. Băile Herculane’s central square.

Fig. 11 Neptune’s Baths, a ruined spa built in the nineteenth century. There are currently campaigns by Romanian citizens to have them restored – according to locals I spoke to, this is expected to happen in the next few years, although there is still some work to be done. The sulphurous baths are shown in the bottom picture.

Fig. 12. The house of Elisabeth of Bavaria (Sissi), Empress of Austria-Hungary from 1854 to 1898.

The Cerna River’s pools, seen from bridges, are used by hotel guests for bathing, despite the water’s sulphurous smell. The town square features a statue of Hercules, said to have inspired the town, Karlovy Vary, in the Czech Republic.

Returning to Bucharest, I contemplated the beauty of Romania’s landscapes and its geology, the warmth of its people, and its rich architectural heritage, making it a remarkable destination in Eastern Europe.

About the author

Marta Pino Larrío is a geologist with a masters in evolutionary biology and palaeontology. During the period covered by this article, she worked in geotechnical engineering on projects related to railway construction and other civil works. She has also collaborated in several palaeontological excavations and in the conservation of the vertebrate palaeontology collections of the National Museum of Natural Sciences in Madrid.

References

Jipa et al. (2011). Zanclean Gilbert-type fan deltas in the Turnu Severin area (Dacian Basin, Romania). A critical analysis. Geo-Eco-Marina, January 2011.

Nastaseanu, S., Bercia, I. (1968). Baia de Aramă. Carte géologique de Roumanie au 1/200.000, 32, Institut Géologique, Bucarest.

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