Researchers from the USA and Vilnius University Sought to Uncover Historical Secrets near the Town of Nida

The Curonian Spit in Lithuania, a favourite destination for holidaymakers, is not only fascinating for its nature: it is also full of historical mysteries, which researchers are trying to explore. Legends say that at the beginning of the 20th century there was a POW camp near Nida, the presence of which has not yet been clearly confirmed or denied. Researchers from Vilnius University (VU), together with colleagues from the USA, searched for its traces too and, at the same time, they also obtained valuable information that could help determine what the dunes in Curonian Spit will look like in the future. Dr Donatas Pupienis, a coastal researcher at the Faculty of Chemistry and Geosciences, tells us about it.

Legends about the POW town

Historians and ethnologists of the 20th century mention in various sources that German authorities of the time had set up a French POW camp in Death Valley near Parnidis Dune, in "response" to the establishment of a German POW camp by the French in Algeria. And even though a symbolic memorial to the prisoners of war was erected on Parnidis Dune at the expense of the French Ministry of Defence, archaeologists who have investigated the site have not found any tangible evidence of the former camp.

"Researchers from Vilnius University and the University of Wisconsin – Eau Claire aimed to create a topographic map of Death Valley and to use geophysical methods to determine the preliminary location of the former French POW camp. The research involved non-invasive geophysical surveying of the dunes using ground-penetrating radars (GPRs) at different frequencies, without disturbing the layers underground. If there are layers of different densities underground (sand, clay, groundwater) or distinctive objects (a tree stump, a stone), we can discover objects of interest this way." – says Dr Pupienis.

According to him, Professor Harry Jol from the USA, together with his students, chose the site while researching the sites of Holocaust victims in Lithuania and Latvia. Yet the information gathered with GPRs is also valuable for the studies of nature in the Curonian Spit. "The second objective is to study Lithuanian and Latvian coastal dunes. The "possible" location of the French POW camp was chosen because the professor and I had previously worked in Nagliai Nature Reserve (in the Dead Dunes), and we had not done any research in Death Valley until then. Interestingly, German cartographers never marked Death Valley on their maps, and only the valley of Silence (Tal des Shroeigens or Tal des Sweigens) can be found. However, a Lithuanian map published in 1990 already contains the name of Death Valley," said the coastal explorer about the legendary region.

Results will help predict the future of the dunes in the Curonian Spit

Although no traces or signs of a French POW camp were found, investigations revealed a layer of lagoon marl at a depth of 1–2 metres. "In wet conditions, lagoon marl is a highly viscous, carbonaceous mud. And even though it has been known about the lagoon marls in the Curonian Spit for more than 150 years, we still don't know how widespread they are and how often they outcrop," explains Dr Pupienis.

The lagoon marl outcrop is recognised as a geomorphological natural monument. According to the researcher, it is special because it outcrops 5000 to 6000-year-old carbonaceous mud, called gyttja, with fossils of molluscs and fish, that has been deposited from the bottom of the lagoon to the surface. For a long time, visitors to the Curonian Spit National Park could admire the squeezes of the lagoon marl that used to be near the western slope of Parnidis Dune, and the height of its outcrop reached 2–3 m. However, over the past almost 20 years, the lagoon marl outcrop has declined and its height is now only 0.1–0.2 m. According to Dr Pupienis, the discovered layers of lagoon marl are a source of joy for researchers, as in the future new portions of lagoon marl may be squeezed out at the foot of Parnidis Dune and a new outcrop of lagoon marl may be formed, thus altering the landscape of the area.

"Lagoon marls are an interesting object of research, as they provide new insights into the formation and development of the Curonian Spit and the dynamics of the Great Dune Ridge. The age of the remains of the lagoon marls in the Curonian Spit can be used to estimate the Curonian Spit's migration rate. At the same time, as the spit shifts from west to east, sediment dating provides a clue to the rate of dune migration. It is interesting to note that theoretically, such a phenomenon should also be present on the coasts of Poland and Russia, where there are sandbars or spits with dunes, but so far we have no scientific data from other countries on the phenomenon of the squeezing of lagoon marls," explained Dr Pupienis.

Although the lagoon marl squeezes provide a lot of information about the movement of the dunes, according to Dr Pupienis, it is still difficult to predict how the Curonian Spit landscape will look like in the future: "In order to create new lagoon marl squeezes, the sand in the dunes needs to be intensively knocked down and moved from the western part of the Curonian Spit to the eastern part. Lately, however, the staff of the Curonian Spit National Park have been trying to preserve the existing dunes, and are attempting to reinforce them in some places (perhaps this is just an experiment). It should not be forgotten that the dunes have recently been heavily frequented by holidaymakers, who sometimes disregard the warning signs and climb up the dunes, thus causing the sand to slip towards the lagoon. Irresponsible behaviour by visitors to the Curonian Spit can also change the landscape," said the scientist.

The research was carried out as part of the project "Imaging Holocaust and Coastal Environments: Latvia and Lithuania“