Tuesday, October 9, 2012

Rising sea levels & faster-rising land affect Viking settlement Birka

Squeezing through reed beds
There are Arthur, Roland and me… just three of us pushing into the westerly breeze across Lake Malaren toward the island Bjorko. Once in shelter we sneak up the eastern side through reed beds beside dense woodland to approach our landing in the northeast. Maybe we’ll have wind at our back for the return.          

 Two tour boats and a number of small sailboats cluster around the sheltered harbor Angholmen. The island looks sleepy. But maybe as long ago as 3,500 years ago the island was used by Bronze Age hunters. There are nine Bronze Age burial cairns at the south end, but what’s better known is that during the 8th and 9th century AD there was a bustling Viking market town here; an important trading center.

These lake islands have dense woodland to the shore
We change from our paddling gear, fire up a stove in the shelter of a tree and make espresso. After lunch we go exploring. First there’s a small museum that shows a lot about the town as it would have been, with an amazing model of the village and fortifications. That’s useful to get an idea of the layout, because much of what remains is below ground, covered by a skin of turf. It’s also an opportunity to see replicas of relics found here, and examples of building techniques.

What we can see is a high outcrop of rock inside the hill fort, Borg. From the top of the rock is an impressive view across the lake and islands.
Wide view from the Viking hill fort Borg
Turning to look inland we can see the retaining fort rampart and ditch, with its gateways. It reminds me of the hill forts on the Sussex SouthDowns in England I used to play in as a kid, although this is much more recent. Outside the fort rampart was once the town, with its own defensive rampart across the valley. This area is currently known as the “black earth”, on account of the color of the earth beneath the grass. This gave early archaeologists an indication that a settlement of some size once stood here. Given the building materials of the period, wood and thatch, there were likely plenty of house fires during the period of occupation adding to the ash from fireplaces used for cooking or metalwork and other refuse that would create the rich soil.

We explore the ramparts of the Viking fort

Outside the distant rampart surrounding the town site is a graveyard, “Hemlanden” (homeland). It’s the largest of its age in Scandinavia and holds some 1,600 graves in the form of barrows, stone ships and stone circles. The island holds more than 3,000 such graves. 

So many graves indicate what a large population center Birka became at that time. Starting in the early 800’s as a trading center, it first traded with south-west Europe, but later switched to trade mostly with the east, with such places as Tashkent and Samarkand. Trade is a two-way process, so goods manufactured in Birka, such as the characteristic oval brooches worn by women, have been found in graves in Russia, while Islamic and Byzantine coins have been found at Birka, along with remnants of other trade goods.
Small Viking boats wait in the reeds

We visit a group of reconstructed houses and garden plots In a small bay on low land that in Viking days would have been below sea level. This hamlet is used both by historians to learn about the building methods used back then, and to educate visitors. Nestled in the reeds nearby against a narrow wooden dock are a few small Viking boats. Adding color to the scene are small groups of people “living the Viking life” dressed in historically correct clothing, cooking over fires and carrying out what would likely have been daily tasks back then. This realistic play-acting reminds me how little things change through the centuries. Many people around the world still live in much this way.

Viking building methods were used in these reconstructions

 We walk the island, between the mounds of the ancient burials, and around the defensive ramparts that once were fortified with wooden walls and towers. It’s easy to imagine the attraction of this site when it was inhabited, but what happened to the population when it declined as a town?

More than 3,000 Viking burial mounds have been found here

Nobody knows that, but it’s known that power shifted next to the town of Sigtuna on the mainland and later again to Stockholm. When Birka was occupied, it was in a bay of the Baltic. That bay reached far inland which being relatively difficult to navigate, added some natural safety from random attack. 

Stockholm sits where the lake meets the sea
As land levels lifted following the ice age, the rock ridge on which the old town of Stockholm stands dammed the bay and created rapids. The body of water above the rapids became Lake Malaren. By 1200 boats arriving at the entrance found the water so shallow they had to unload goods to haul the boats up. 

Point65's Richard Ohman approaches the lock in Stockholm

 Now Stockholm guards the entrance to Lake Malaren and its locks allow boats to drop smoothly from the lake on average 0.7 meters to sea level. The land is still rising, though less slowly now, at a rate of about 1 cm per year.

Evening, the lake side of the lock

 More about Birka