For prehistoric coastal inhabitants, sea level change was common. In the Orkneys, the Stone Age people even built their shrines along lakes and seas with dynamic coastlines.
Sea level rise is a real nightmare for us. But people must have been familiar with it as far back as prehistoric times, according to Caroline Wickham-Jones. The Scottish archaeologist has been researching the Orkney Islands for decades, an archipelago about ten kilometers off the coast of northern Scotland. Now the archipelago consists of approximately seventy islands, but immediately after the last ice age it was a landmass consisting of two large islands, with an area twice as large as today.
“The Stone Age people were used to adapting to sea level rise. The landscape was constantly changing,” said Wickham-Jones. “For us modern people, the landscape has been the same for a long time. Due to the low population pressure, the prehistoric inhabitants were very flexible when a piece of land was flooded somewhere. They could easily settle in another place. But it is striking that their ceremonial buildings are located in vulnerable places.”
Immigration after the Ice Age
The very first inhabitants of the Orkneys settled there about 8,000 years ago, during a period known as the Mesolithic. The first explorers probably visited the islands 4000 years earlier. It was right after the last ice age, when the snow and ice in the Northern Hemisphere began to melt. This made more land available.
These Paleolithic hunter-gatherers left few traces. The arrowheads that have been found are very similar to the arrowheads of hunters who roamed the European mainland. These groups traveled long distances on their annual hunting routes. Archaeologists believe that some groups came from the Dogger Bank, a part of the North Sea that was submerged after the Ice Age, and that the hunters eventually reached Orkney via the coast.
During the Mesolithic, sea levels around Orkney rose relatively fastest. Between 9000 and 7000 years ago this was about 10 cm per 25 years. On low-lying islands such as the Orkney Archipelago, this must have led to a lot of land loss. When the first farmers arrive, about 6000 years ago (the Neolithic), the sea level rise is slower. 4000 years ago the sea level at Orkney was already comparable to the present level.
Sanctuaries in a vulnerable area
Most of the Stone Age monuments on the Orkneys date from the early days of peasant society (the Neolithic, between 5500 and 4500 years ago). Although the sea level rise was less than in the previous period, it is striking that the important monuments from that time are located on a vulnerable isthmus that became narrower and narrower at that time due to the rising sea. It is also striking that the lake adjacent to the isthmus (Loch of Stenness) changed from a freshwater lake into a brackish one several centuries earlier for the same reason.
The famous Ring of Brodgar stone ring, the Stones of Stenness and the coastal Skara Brae date from the Neolithic. Here you can see 'Stone Age houses' with stone furniture. This world-famous World Heritage archaeological site receives thousands of tourists every year. The archaeological site became visible when a lot of sand was knocked off in the dune area after a strong storm. When the settlement was built, it was several miles inland; even then it was on a bay. The most recently found excavation site, Ness of Brodgar, dates from the same period, and was accidentally discovered during a soil investigation in 2002.
Symbolic meaning of water
Archaeologists believe that water had a strong symbolic meaning for prehistoric man. “Possibly it marked the transition into the realm of the spirits,” Wickham-Jones said in a telephone interview from her office on the Orkneys. Her theory is that the ceremonial structures are even deliberately placed in vulnerable areas in an attempt to 'conjure' the water, as it were.
In the Netherlands we also see that Stone Age burial mounds are often built near a water surface. For example, the burial mounds to the west of Einhoven were constructed next to a large fen, which is still recognizable in the landscape as a low plain.
Landscape for archaeologists
Archaeologists are increasingly involving the surrounding landscape in their work. Landscape data allows for a better interpretation of the past. This means that past climate change is also interesting for archaeologists.
But it also means that the reconstruction of the landscape cannot be done solely on the basis of models, because these are often too coarsely meshed. For example, in the Atlas of the Holocene on an image we see that Orkney was connected to the Scottish mainland 8,000 years ago. “A typical mistake,” says Wickham-Jones, “which is understandable if you connect two points whose data is known with a straight line. The more points you have, the more accurate the image. In archeology you need a lot of detail because you study individual settlements. Modeling is fine to get a general impression, but to understand the organization of small communities, you need more detailed information.”
Drowned settlements
In recent years, bathymetry (which maps the topography of the seabed), drilling and diving operations have explored the Orkneys' shoreline in multiple locations to map changes in the landscape. During these searches, an annular structure was discovered five meters deep in the Bay of Firth, in the central part of Orkney. Archaeologists are now investigating whether this is indeed a Neolithic monument. “We don't expect this to be a large settlement, but we suspect that there are many small settlements around Orkney, although few will be intact now.”
In fact, indications have been found on the seabed at Skara Bray of a drowned forest around 6000 years old. It is covered with sediments, but has therefore also remained protected. There are probably drowned forests in more places along the coast, archaeologists suspect. Pollen analysis shows that the now virtually treeless islands were once covered with trees and shrubs. Periods of extreme rainfall, in combination with the felling of trees by the Mesolithic farmers, would have put an end to this.