Bulverket (Gotland)

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location
Post recovery 1927

Bulverket refers to the remains of a large timber plant in Lake Tingstädeträsk on Gotland . These remains are now spread out in large piles on the lake bed.

According to the 1989 research, the fortress was built in the 1130s. As excavated bottom sediments show, it was not used for long, maybe only half a century. The name Bulverket comes from the Swedish word “bul”, which is related to the German “Bohle”, meaning “tree trunk” or “beam”, while the second part of the word “verket” indicates something built. It is also related to "Bollwerk" ( English "bulwark" ), which is a type of defensive structure, similar to the Dutch "bolwerk" . The purpose of the structure is unknown; possibly it was an "expression of resistance to royal and episcopal claims". Because the lake Tingstädeträsk has a natural sedimentation , the remains of the Bulverket have been preserved so that the finds are preserved in a very good condition.

Aerial view of the Bulverket

construction

The Bulverk consisted of four rows of houses arranged on a square platform; the side length was 170 meters. The corners of the square were oriented in the four cardinal directions. In the middle of the facility there was an open, sheltered water area with jetties on which one could probably moor boats. The bulverk was surrounded by a round wreath of stakes that were anchored in the seabed. Sometimes this ring extended almost 50 meters into the water; it consisted mostly of double rows.

The main construction consisted of wooden boxes. There were both residential houses and storage buildings that were executed in different techniques: timber frame construction , block house and bar technology (as in stave churches , Swedish "stavteknik" or Swedish "stavverk" ). In total, the system consisted of around 25,000 trunks, mostly made of pine , which corresponds to a forest area of ​​50 hectares. The number of daily work required to build the facility is estimated at around 38,000; Research suggests that construction could be completed quickly, perhaps in a single year, which would mean around 100 men were employed during that time. If you take into account the whole organization around the work and the fact that the farms could not spare their labor for a whole year to build the Bulverk, large parts of northern Gotland must have been involved in the project.

discovery

It is considered likely that the local population knew the Bulverk all along; but there is no oral tradition of its construction, purpose or fate. The first written mention is attributed to Oscar Montelius in 1868. He mentions that the naturalist and teacher Lindström discovered stakes in Tingstädeträsk in 1866. But an old local saying is Det rökte så som när Tingstädeträsk brann. (Translated: It smoked like when the Tingstädeträsk was burning. ) Perhaps that reveals something about how the buildings in the lake were destroyed.

Investigations

1921-1936

Arvid Zetterling, then a captain in the Gotland artillery regiment, discovered the Bulverket in 1907 while fishing on the Tingstädeträsk; he was amazed at the wooden beams he saw on the lake floor. In 1915 Zetterling carried out a small investigation of the bulkhead. But it wasn't until his retirement in 1918, when he was appointed major in the reserve, that he was able to invest more time in his hobby. The serious investigation began in 1921, although he was living in Hässleholm at the time . Zetterling retired completely in 1932 and was then able to devote more time to Bulverk. During 1932–1935 he rented an apartment in Furubjärs gård in Tingstäde , where he also founded a museum about the Bulverk. However, this closed again after his death.

Zetterling was an amateur archaeologist who worked with very limited resources. He carried out underwater excavations with tools he made himself; he drew large parts of the Bulverk with the help of pencil and paper, sitting on a chair like the kind that tennis umpires use. Thanks to good contacts, he was able to obtain aerial photos that had been taken over the lake. Zetterling was probably the first in Sweden to use aerial photographs for archaeological purposes. During the excavations, Zetterling mainly came across various types of timber , including the remains of two different types of boats, but also objects made of bronze, floating bodies , hazelnuts, bones of cattle , sheep , pigs and poultry. He also found remains of wood damaged by fire, from which he concluded that the Bulverk was largely destroyed by fire. He also made a 1:50 scale map. Zetterling died in 1938.

Zetterling's investigations are summarized in the report given in the reference.

1989-1994

The last investigations were carried out from 1989 to 1994 by Johan Rönnby and others. Among other things, they used side-sighting sonar to map the lake floor. Stratigraphic surveys were carried out on a large area of ​​27 x 2.5 m² with 20 drill cores taken from different locations. No cultural layer was encountered, suggesting that the Bulverk was not used as a residence for an extended period of time. No trace of a fire was found either, which indicates that a possible fire was only local and could not have destroyed the entire facility. Instead, it is concluded that the Bulverk became unstable, abandoned, and simply collapsed. Dendrochronological studies and radiocarbon dating (C14 method) indicate that the Bulverk was built in the 1130s. That gave as a date for the outermost annual ring 1121, 1124 and 1129. However, it was later determined that the reference used for the current period was incorrectly dated and must be corrected by nine years. This means that the dates given in Bråthen's and Rönnby's books have to be brought forward nine years to be correct. The trees were felled and probably built in the 1130s. The lifespan of the bulk is estimated to be around 50 years.

analogy

The Bulwarks is a promontory fort in Rhoose, Vale of Glamorgan , on the south coast of Wales on the Bristol Channel . It probably dates from the Iron Age and continued to be used in Great Britain during Roman times. However, the name is Nordic.

See also

swell

  1. ↑ 1130 Ragnvald died (Sweden)
  2. ↑ a b Johan Rönnby: Bålverket. Om the collection route and the point of departure from the tidigmedeltida Bulverket i Tingstäde träsk on Gotland. Study från UV Stockholm. Riksantikvarieämbetet, Arkeologiska Undersökningar, Skrifter nr 10, Stockholm 1995, ISBN 91-7192-974-6 , ISSN  1102-187X (Swedish).
  3. ↑ Johan Rönnby: förflutet Sjunket. Arkeologiska möjligheter under vatten. Runius & Co förlag, Stockholm 2001, ISBN 91-974166-1-4 (Swedish).
  4. ↑ Arvid Zetterling: Bulverket - en svensk pålbyggnad i Tingstäde träsk på Gotland . In: Fornvännen . tape 22 , 1927, pp. 161–178 ( fornvannen.se [PDF; accessed on January 14, 2012] in Swedish with a German summary; PDF file, 2 MB).
  5. ^ Arvid Zetterling: Bulverket i Tingstäde träsk - 1927 års undersökning . In: Fornvännen . tape 23 , 1928, pp. 27–37 ( fornvannen.se [PDF; accessed on January 14, 2012] Swedish with a German summary; PDF file, 1 MB).
  6. ^ Arvid Zetterling: Bulverket - en förhistorisk sjöfästning i Tingstäde träsk på Gotland. In: Svenska fornminnesplatser. 10, 1929 (Swedish).
  7. ^ Alf Bråthen: Dated wood from Gotland and the diocese of Skara. 1995, ISBN 87-87270-75-7 , pp. 56, 120.
  8. ↑ Thomas Bartholin: Dendrokronologiens tilforlidelighed . In: Fornvännen . 1998, p. 141 f . ( fornvannen.se [PDF; accessed on January 14, 2012]).
  9. ↑ Alf Bråthen: Commentary till Thomas Bartholin's article om dendrokronologins tillförlitlighet . In: Fornvännen . 1998, p. 258 f . ( fornvannen.se [PDF; accessed on January 14, 2012]).

Web links

Coordinates: 57 ° 43 ′ 40 "  N , 18 ° 37 ′ 43"  E