In the early Stone Age, the water levels in the small lakes located in the southern parts of what are today Lake Kuolimojärvi and Saimaa were several metres below the present levels. After this period, the water levels started rising as a result of uneven land uplift and the tilting of lakes and rivers. The rise in water levels ended with the outburst of River Vuoksi through the Salpausselkä Ridge about 6,000 years ago when water masses carved a new southeastern outflow channel towards Lake Ladoga.
With the rise in water levels, areas that were on dry land in the early Stone Age have been buried in the bottom of the lake and its littoral deposits.
The aim of the three-year study carried out by the University of Helsinki has been to find traces of early Stone Age settlements under water and from wetlands at lakes Kuolimojärvi and Saimaa.
“This means that there is a huge gap in our archaeological knowledge of this particular area because we have not yet found the earliest Stone Age sites,” explains postdoctoral researcher Satu Koivisto who heads the project.
So far the oldest sites have been settled after the breakthrough of River Vuoksi (6000 years ago and onwards). However, there has definitely been human habitation in this area for thousands of years before that, as is shown by the traces of settlements of more than 10,000 years old discovered at Kuurmanpohja in Joutseno further to the south.
Charcoal, burned rocks and quartz flakes have been found at the site
In June 2018, archaeologists carried out underwater excavations and equipment testing at Kammarlahti bay in Savitaipale in cooperation with Nordic Maritime Group (NMG) and the underwater unit of the Finnish Heritage Agency. Archaeologists from Denmark and Sweden also took part in the work.
The work started with a thorough study of the lakebed the purpose of which was to find archaeological remains by mapping the best-preserved areas.
“The western side of the Kammarlahti bay is sheltered from wind and waves and for this reason, the prehistoric dry land areas are best preserved in that part. In one of the test pits, we found a distinct layer of burned soil, charcoal and burned rocks. Quartz flakes were also found in the surrounding test pits and these remains show that quartz artefacts had been made at the site during the Stone Age,” Koivisto explains.
The hearth feature and associated find materials indicate that a submerged Stone Age settlement site has now been located at Lake Kuolimojärvi – the first undisputed observation of this kind in Finland. The nearest similar sites are located in northwestern Russia and southern parts of Scandinavia. It is clear that the hearth feature, which today lies at a depth of about one metre, and the other finds are from the period before the rise of the water level (about 9,000 to 8,000 years ago). The archaeologists managed to take a soil sample of the burned layer around the hearth and are now trying to find datable material from it.
"With the excavation equipment tested in the underwater research at Kammarlahti, we may also be able to find other submerged sites at similar locations. For this reason, the discovery opens up an entirely new era in the research into the Finnish Stone Age. Many of our large lakes, such as Vanajavesi, Pielinen and Oulujärvi have also gone through similar fluctuations in water levels. This means that a huge and largely untapped archaeological resource is hidden in Finnish lakes. Moreover, extremely old organic materials may also have been preserved in these environments for thousands of years,” Satu Koivisto says, describing Finland’s underwater archaeological potential.