Archaeology in the North Sea
Archaeology in the North Sea
The Orkney Vole is thought to have been imported, by uncertain means, to the archipelago from mainland Europe without setting foot on mainland Britain.
How this happened is a bit of a mystery.
At present, the scope for a small rodent to migrate between Denmark, Germany, the Netherlands, or France, and Orkney, without touching Britain seems a bit limited.
"Orkney voles have evolved their own particular dental phenotype, likely the result of human agency influencing its evolutionary trajectory in different ways over the last 5000 years. This human influence began with its Neolithic introduction to the Orkney Mainland at a time when there were no terrestrial predators and only one competing species (the wood mouse). The Orkney vole population rapidly diverged from continental European M. arvalis to reach a new ecological optimum, that included evolutionary changes in morphology of the molar teeth. Neolithic farmers then dispersed the species to other islands of the archipelago—from Mainland to Westray and during the Bronze Age to Sanday—generating several founding events contributing to idiosyncratic differences in dental characteristics." (Cucchi et al)
"M. arvalis is not a species currently associated with arctic or even moderately high latitude conditions. Its range extends eastward beyond Lake Baikal and yet barely traverses north of the 60th parallel (Fig. 2; Shenbrot & Krasnov2005).....
"M. arvalis is not currently found in Britain(Fig. 2)......
"It is conceivable that there could have been sweepstake colonization of Orkney from Doggerland, the landmass connecting Britain, the Low Countries and Denmarkuntil about 8000 BP (Weninger et al. 2008) – but this would require the survival of small mammals on floating mats of vegetation over a substantial marine gap between Doggerland and Orkney. Thus, human introduction is by far the most likely explanation for the occurrence of M. arvalis on Orkney......
"From the IMa and ABC dates, this introduction at about 5000 BP fits well with the earliest radiocarbon dates for archaeological M. arvalis from Neolithic contexts (5100 years old: Table 2) and the beginnings of the Neolithic culture on Orkney (5600 BP: Ritchie 2001; Schulting et al. 2010). Voles could have been brought to Orkney by Mesolithic hunter-gatherers, as early as c. 9000 BP, but no vole remains have been found in the one excavated Mesolithic site on Orkney (Lee & Woodward2009), in contrast to their abundance at Neolithic and later sites (Yalden 1999; Thaw et al. 2004). If, as appears most likely, the voles were introducedby Neolithic settlers about 5000 BP, various other implications flow from our molecular data, which are of considerable archaeological interest. First, the introduction implies long-distance maritime travel by Neolithic people between continental Europe and Orkney, extending on findings from elsewhere (e.g.Broodbank 2006). Our study highlights the Belgian coastline as the most reasonable source of the Orkney voles on the basis of available genetic data. This suggests Neolithic cultural linkages between Belgium and Orkney, of worthwhile focus for future archaeological investigation. Microtus arvalis were not introduced successfully into mainland Britain, which is consistent with relatively direct transport to Orkney from the continental source area. Second, if the introduction occurred about 5000 BP, then, because the tMRCA for the Orkney voles is so long (15 400 years), substantial numbers of femalevoles must have been introduced." (Martinkova et al)
The possibility that walkable land was present in the middle of the northern North Sea has not been addressed. To establish this possibility that land was present in the middle of the North Sea in prehistoric times the undersea features there need to be recognised. These are in simple terms, Dogger Bank, the Witch Ground and the Norwegian Channel.
Fig. 1, The British Isles and North Sea (Emodnet)
The Norwegian Channel is a deep water trench that follows the Norwegian Coast from the Skaggerak, (an even deeper section of the same trench), between Norway and Denmark, out to the North Atlantic Ocean.
Dogger Bank is an area of shallow water in the southern North Sea known to have been walkable land in prehistoric times, Doggerland.
The Witch Ground is one of a group of deep water features in the North Sea. These gullies are cut into older sediments, and are all the result of impact erosion. Ice sheet edges collapsed, between around 21,000BP and 17,000BP, cutting valleys in underlying ground that was at that time mostly dry land.
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The Norwegian Channel is an impact valley that has for millions of years been cut out by ice sheets on Norway and scoured by mobile ice streams rolling off from Sweden, into the Skaggerak, and out to the Atlantic Ocean.
The sea level charts for changes in relative sea-levels for points along the Norwegian Coast, are published in "Post Glacial Relative Sea Level Change in Norway" by Roger C. Creel. These charts are attached to the map of the Norwegian Channel below.
Fig. 2, Sea level charts for the Norwegian Coast (Creel)
There is, on the charts, a consistent pulse of 10 metres higher water level onto the Norwegian coast at 12,000BP when the ice sheets on Sweden were melting and draining into the Skaggerak.
The sea level in the Norwegian Channel, inferred from "Global sea-level rise in the early Holocene revealed from North Sea peats" by Marc P. Hijma, et al, was 60 metres below present at 12,000BP, but the peak of the meltwater surge out of the Skaggerak was then 10 metres above 60, therefore 50 metres below our sea level.
This surge of 50 metres below sea level was supported at the Skaggerak between the coasts of Norway and Denmark, and not diminished in any way until it had followed the Norwegian Coast and reached the Atlantic.
This means that there was land along the west bank of the Norwegian Channel at better than 50 metres below current sea level, where the seabed is now over 100 below.
This suggests that there was land at the west coast of the Norwegian Channel at shallower that 50 metres below sea-level that people and animal may have used to walk from Doggerland north to the Atlantic coast of the North Sea.
Figure 3, a flint found in a borehole drilled in the seafloor of the northern North Sea.
To confirm this possibility, There is evidence of human activity in the middle of the North Sea.
In a report entitled "A flint artifact from the northern North Sea" . Caroline Wickham-Jones discusses a struck flint artefact found in a borehole in the North Sea, half way between Shetland and the North Sea, ("A flint artifact from the northern North Sea" By Long, D., Wickham-Jones, C.R. and Ruckley, N.A. 1986).
The location of the find, the "Findspot", is indicated in the map above, and the artefact itself is drawn. This may indicate that people were foraging in this area in prehistory. It is certainly difficult to conceive how a knapped flint got to that place otherwise.
During the cold period of the last glacial maximum, all of eastern Britain from Dover to Orkney was ice covered. Thick ice also covered Dogger Bank/Doggerland, and the peninsula that extended north from there to the findspot, and the Atlantic Ocean.
There are then the two routes by which the Orkney Vole may have migrated to Orkney. The first is as a population surviving through the last glacial maximum on yhe shores of a lagoon, and the second, perhaps more plausible, would have been north from Doggerland, and around the south coast of the Shetland embayment.
The materials that built up the peninsula would have arrived in their current locations by deposition from large volumes of mobile sludge waves derived from the collapse of ice sheets on Shetland. As the deposits on the peninsula would not have been overlaid by a great thickness of ice they would have been reasonably soft. It was only when sea levels rose that these, otherwise stable deposits began to collapse.
The Inundation of the North Sea
The ridge of land that joined the "Findspot" to Doggerland has been removed as a result of rising sea levels.
The date at which this happened may be found in a report of excavations of raised beaches on the Norwegian Coast that was carried out by Lisbeth Prøsch-Danielsen (Sea-level studies along the coast of south-western Norway, by Lisbeth Prøsch-Danielsen) At the "Stavanger Airport Sola Site"
Fig, 5. The Rogaland coast of Norway (Prøsch-Danielsen)
Danielsen demonstrated that there were a couple of transgressive rises in sea level after the end of the last ice age. She also found an anomalous event which she could give no explanation for, in which an alder tree was ripped from its roots at a site in Rogaland, near Stavanger. “The layer consisted of organic and sand (mica schist) lenses sandwiched on top of each other, dipping towards the east. Between layer 3 and layer 4 there is an erosional angular unconformity. Also roots of black alder (Alnus glutinosa) (identified by Aud Simonsen) penetrating into the upper part of the marine gyttja have been cut of discordantly. A piece of root has been dated to 4320±70 yr BP (ß-171185).”. The date was calibrated to just after 3000BC, and I interpret that the roots may have been stripped of their tree by a very local tsunami wave, rolling across the Norwegian Channel from the collapse of cliffs along the west coast of the channel.
Similar results to those at Stavanger airport Sola site, were found at other archaeological sites in Rogaland, where tsunami-type deposits are found.
Talking to Bård Amundsen, a journalist for sciencenorway.no , Svein Vatsvåg Nielsen and his German colleague Martin Hinz say:- "We now consider it certain that the sea level rise was brief. It also seems likely that a tsunami struck the Stone Age people in Rogaland – and probably also Vest-Agder – sometime between 3445 and 3396 BCE,"
Nielsen and Hinz suspect that it may have been the Garth tsunami, named after the Garth Loch lake in Shetland.
Jåsund 2 is the name archaeologists have given to one of the most well-known Stone Age settlements in Rogaland. It is located on the Tananger Peninsula in Sola municipality, just outside Stavanger. Evidence suggests Jåsund 2 was flooded by a wave possibly as high as 10 metres.
They have also discovered evidence of the Garth tsunami, which may have hit southwestern Norway 5,400 years ago, on Shetland. The sediments left behind by this tsunami are similar to those from the Storegga tsunami. In this case, the wave run-up on land is over 10 metres.
Håkon Glørstad, who first proposed the tsunami theory in the 1990s, is pleased that Nielsen and Hinz have now confirmed it in a new scientific article. "At the time, much of what we uncovered in archaeological digs in Rogaland didn’t make sense," Glørstad tells sciencenorway.no. "But I realised something dramatic must have happened, something involving water, that was unique to Rogaland. It had to be a fairly local phenomenon," he says. (Amundsen, edited)
The last ice age is not well understood at present, but the research that has been necessary to plot a path by which the European Vole transformed itself into the Orkney Vole required a series of shifts in my perception of Quaternary landscapes.
The theories of how the ice-sheets affected the land upon which they rested, as they are proposed by scientists in existing polar science, often bear no relation to the actual conditions as they survive. A common feature of these theories is that ice-sheets are believed to move, and in some circumstances can move uphill. Although there may be some truth in these statements, they are generally physically impossible.
I have completely redefined the processes that modified the geological landforms, submarine seascape of Britain. I cannot say that this applies to other regions, or to what is happening now, but the geology tells its own story.
Find out more in "Ice-sheetBritain".
A land bridge between Scotland and Orkney does not make any sense for our view of Neolithic Migration if our ancestors had to cross the English Channel in a boat, but could walk from Scotlandto Orkney.
"Walkable Land in the North Sea" charts the evidence for the existence of a land bridge between Holland and Norfolk allowing flora, fauna, and people, to commute between Europe and Britain in human prehistory.
The existence of land between Holland and Norfolk makes it easier to explain that a similar corridor of land would have linked Orkney to Scotland. This also explains how huge monuments could have been constructed by Neolithic people in a sparsely populated Orcadian environment.
Using archaeological evidence "Neolithic Migration to Orkney" tracks the occupation of Orkney from the Neolithic to Bronze Ages. It describes how the more sophisticated structures there, including Skara Brae, and the Ness of Brodgar, were the creation of small groups of people who became stranded on the islands when the link that joined them to Scotland was washed away by rising sea levels.
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Next:- "Mainland Settlements"
All views and opinions expressed are my own. Many assertions stated have not been thoroughly justified here, simply because space prohibits it in this format. The evidence exists elsewhere to demonstrate that these assertions are, at their core, valid.
Jeffery Nicholls
South Ronaldsay
Orkney
Jiffynorm@yahoo.co.uk
(Cucchi) The Changing Pace of Insular Life: 5000 Years of Microevolution in the Orkney Vole (Microtus Arvalis Orcadensis) by Thomas Cucchi et al
(Martinkova) Divergent evolutionary processes associated with colonization of offshore islands, Natalia Martinkova, et al
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