Loholmen. Marinarkeologisk förundersökning Långared 2:1 och 2:2, Långareds socken, Alingsås kommun Delia Ní Chíobháin Bohusläns museum Rapport 2010:53

Transkript

1 Loholmen Marinarkeologisk förundersökning Långared 2:1 och 2:2, Långareds socken, Alingsås kommun Delia Ní Chíobháin Bohusläns museum Rapport 2010:53

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3 Loholmen Marinarkeologisk förundersökning Långared 2:1 och 2:2, Långareds socken, Alingsås kommun Bohusläns museum Rapport 2010:53

4 ISSN Författare Delia Ní Chíobháin Grafisk form Gabriella Kalmar Layout och teknisk redigering Lisa K Larsson Omslagsbild Foto taget av Delia Ní Chíobháin. Fotot visar undersökningsområdet från sydost. Tryck IT Grafiska AB, Uddevalla 2010 Kartor ur allmänt kartmaterial, Lantmäteriverket medgivande Kartor godkända från sekretessynpunkt för spridning Lantmäteriet Dnr /2371 Bohusläns museum Museigatan 1 Box Uddevalla tel , fax

5 Innehåll Svensk sammanfattning...5 Background...5 Landscape...5 Natural landscape...5 Cultural environment...8 Fornlämningsmiljö...8 Ancient monument environment and... previous investigations...9 Method...10 Results...11 Långared 2:2 - permanent fishing trap (A1)...11 Långared 2:1 - cultural layers (A2)...11 Documented finds...12 Discussion...13 Conclusion and recommendations...13 Referenser...14 Litteratur...14 Otryckta källor...15 Tekniska och administrativa uppgifter...16 Appendices... 17

6 4 Bohusläns museum 2010:53 Figure 1. Section of GSD-Property map with the location of the investigation area marked. Figur 1. Utsnitt ur GSD-Röda kartan/fastighetskartan med platsen för undersökningen markerad.

7 Loholmen 5 Svensk sammanfattning På uppdrag av Antens Kommunikationsmuseum utförde Västarvet genom Bohusläns museum i augusti 2010 en marinarkeologisk förundersökning i anslutning till fornlämning Långared 2:1, vilken utgörs av ruinen efter Loholmens medeltida borg. Undersökningen utfördes med anledning av planerna på att uppföra en brygga på den nordöstra delen av ön Loholmen. Arbetet omfattade okulär besiktning av ett kvadratmeter stort bottenavsnitt samt grävning av ett mindre antal provgropar. Inom området framkom ett tunt kulturlager med bland annat tegel, huggspån, keramik och bearbetat trä, vilket visar att utbredningen av Långared 2:1 kan utsträckas mot nordost. I den norra delen av området påträffades en trolig fiskeanläggning. En 14 C-analys visar att denna sannolikt uppförts någon gång under eller början av 1800-talet, och den är således inte samtida med borgen. Eftersom inga fynd eller anläggningar av antikvariskt intresse framkom inom själva etableringsområdet för den planerade bryggan har museet inga synpunkter på den föreslagna exploateringen. Background In August of 2010 Västarvet through Bohusläns museum, in cooperation with Vänermuseet, carried out a preliminary underwater archaeological investigation in an area of water off the south-west of Loholmen in Loviken, Långareds socken, Alingsås kommun (figure 1 3). The preliminary investigation was undertaken by request of the client, Antens Kommunikationsmuseum, who plans to construct a jetty on the north face of Loholmen to facilitate the mooring of a tourist steamer at the site (figure 4). The jetty will be moored in place using concrete anchors. The purpose of the preliminary investigation was to determine the presence and extent of submerged archaeological remains in the area and to limit potential damage to sites by the development. Registered monuments on the island include Långared 2:1, the ruins of a medieval castle dating from the early 1300s and Långared 330:1, the foundations of a bridge which connected the island to the mainland which date to 1301 or shortly thereafter (Bergstrand 2003). Landscape Natural landscape Lake Anten is located 50 kilometers north east of Göteborg and 30 kilometers to the south of lake Vänern. The lake covers an area of 18 square kilometers and has an average water depth of 30 meters. An outlet to the south connects Anten to Ålandsjön and onto Mjörn. Loholmen island is situated in the northeast of the lake, within Loviken, circa 200

8 6 Bohusläns museum 2010:53 Figure 2. Section of GSD-Property map with the location of the investigation area marked. Scale 1: Permission for distribution approved by the Security Officer. Lantmäteriet Dnr /2371. Figur 2. Utsnitt ur GSD-Fastighetskartan med platsen för undersökningen markerad. Skala 1: Godkänd ur sekretessynpunkt för spridning. Lantmäteriet Dnr /2371.

9 Loholmen 7 Figure 3.. Section of GSD-Property map, sheets 7A 5j, 7A 5a, with the investigation area and nearby ancient remains marked. Scale 1: Permission for distribution approved by the Security Officer. Lantmäteriet Dnr /2371. Figur 3. Utsnitt ur GSD-Fastighetskartan, blad 7C 8b, med översikt över undersökningsområdet samt närliggande fornlämningar markerade. Skala 1: Godkänd ur sekretessynpunkt för spridning. Lantmäteriet Dnr /2371.

10 8 Bohusläns museum 2010:53 Figure 4. Investigation area towards the southeast. Photo Staffan von Arbin. Bohusläns museum. Figur 4. Undersökningsområdet mot sydost. Foto Staffan von Arbin. Bohusläns museum. meters from the shore. The water between the northern extent of the island and the shore measures at most four meters deep and the bottom consists of sandy sediments. Cultural environment Västergötland had the most number of castles from the medieval period until 1530, largely due to its borders with Denmark and Norway. Most early castles, from the early medieval period, were built purely for defensive reasons and were used as royal residences. During the 1100s bishops had begun to build castles and by the 1200s wealthy individuals were constructing castles for their own use (Ekre 1992). The earliest written evidence of Loholmen castle is from 1312, when Gudmar Magnusson and Margaret Ulfsdotter of the Hjorthuvud dynasty resided there during the early 1300s. Margaret was given Loholmlen by her relative Eskil, a brother of Birger Jarl. Gudmar served as a knight, as a judge in Västergötland and was also in the privy council (riksråd). In the late 1400s Loholmen came into the hands of Erik Abrahamsson of the Lejonhuvud house and Ebba Eriksdotter of the Vasa dynasty. Erik was executed at the Stockholm bloodbath of 1520, after which Ebba and her six children moved from Ekeberg to live in Loholmen castle. One of their children, Margaret, married King Gustav I (Vasa) after he came to Loholmen for courtship following the death of his first wife Katarina in 1535.

11 Loholmen 9 Figure 5. Plan of the archaeological finds and features in the water surrounding Loholmen, located by MASG in Björn Dahrén, MASG (permission granted from illustrator for publication). Figur 5. Plan över arkeologiska fynd och lämningar i vattnen kring Loholmen, lokaliserade av MASG år 2002 (Björn Dahrén, MASG). The last owner of Loholmen castle was their second eldest son, Sten Eriksson Lejonhuvud and Ebba Månsdotter from Upplo. Following Sten s death from a sword wound in Stockholm s stortorget in 1568, his wife Ebba moved to Gräfsnäs castle, located on the mainland two kilometers northwest of Loholmen. Gräfsnäs castle was constructed in late Renaissance style using building material from Loholmen castle (Dahrén & Fransson 2004:7). Ancient monument environment and previous investigations Earlier research in the area includes a limited archaeological survey of Loholmen in 1936 by the former county antiquarian Harold Olsson. Known ancient monuments in the area include Långared 2:1 which are the remains of the aforementioned medieval castle on Loholmen and Långared 330:1. The latter was located during a marine archaeological survey conducted in 2002 and 2003 by Marinarkeologiska sällskapet, Götheborgskretsen (MASG). The survey focused on the remains of what was interpreted as a bridge which connected Loholmens western extent to land, 200 meters across the strait (figure 5). The remains consisted of twelve stone caissons and a bridge head constructed using wooden frames with dove-tail joints

12 10 Bohusläns museum 2010:53 Figure 6. Timber with construction joint (Långared 330:1). Photo taken in September Photo Staffan von Arbin. Bohusläns museum. Figur 6. Timmer med ok-konstruktion (Långared 330:1). Foto taget i september Foto Staffan von Arbin, Bohusläns museum. and filled with stones (figure 6 and 7). The caissons measure approximately from 5 3 meters to 5 5 meters in size while the individual stones range in sizes from meters to meters. Other features recorded during the survey were the remains of a pier on the western face of the island; cultural layers and several stray finds consisting of construction timbers and boat components which were located to the north and west of the island. Dendrochronological analysis in 2003, in association with Bohusläns museum, was conducted on several oak and beech timbers from the stone caisson frames. The analysis yielded a date of 1301 or shortly thereafter for the bridge construction. One stray timber returned a date after 1495 and was not thought to have been part of the bridge construction (Bergstrand 2003). Method The area investigated measured square meters and the diving was carried out in water measuring at most three meters deep (appendix 1). The area was visually inspected by diving archaeologists, which revealed a number of finds (appendix 4). Based on the results of the visual investigation three test trenches were dug with the use of a water dredge, the contents of which were then sieved for archaeological finds (appendix 3). All diving was carried out with tethered surface-supplied diving and diver-surface communications in accordance with the Work Environment Authority s (Arbetsmiljöverkets) regulations of commercial diving (AFS 1993:57) and the diving standards of Bohuslän museum. All positions were recorded using DGPS. Figure 7. Stones from a stone caisson (Långared 330:1). Photo taken in September Photo Staffan von Arbin. Bohusläns museum. Figur 7. Stenar från en av stenkistorna (Långared 330:1). Foto taget i september Foto: Staffan von Arbin, Bohusläns museum. Figure 8. Fragments of tile from the shoreline. Photo Staffan von Arbin. Bohusläns museum. Figur 8. Tegelfragment från stranlinjen. Foto Staffan von Arbin. Bohusläns museum.

13 Loholmen 11 Results The visual inspection of the area and its surroundings revealed a number of finds and features as noted on the site plan (appendix 1) and as listed in appendix 3 and 4. Within the inspection area a concreted metal object (F1) and a plank of timber (F3) were located. Outside of the investigation area five timber poles (A1) were located protruding from the sediment, the possible remains of a fishing trap, and to the south of the investigation area two substantial pottery shards, from the same vessel, were discovered (F2). The pottery has been preliminarily dated to the 1400s. Furthermore, several worked oak timbers, possibly remains from the above mentioned bridge foundations, were located, and along the shore of Loholmen bricks and brick fragments were observed (figure 8). Three test trenches were dug in the vicinity of the proposed jetty. The trenches yielded evidence of cultural layers in the form of fragments of bricks, wooden chips, and charcoal fragments. Långared 2:2 - permanent fishing trap (A1) A group of at least five wooden stakes were located to the east of the investigation area (figure 9 and 10) and were interpreted as having formed part of a permanent fishing trap. The stakes, of uncertain species, measured 4 6 centimeters in diameter and were partially eroded where exposed. Three of the stakes were heavily eroded and protruded some decimetres from the sediment while two stood at a height of circa one meter. The stakes surrounded four large stones, measuring on average 50 centimeters, as there were no other features on the sediment in this area it is thought that they may have been associated with the poles. Carbon dating of a timber fragment was conducted at Ångströmlaboratoriet, Uppsala University (appendix 2). The 14 C analysis was conducted on a sample from one of the stakes and yielded a result of 190±30 BP, which calibrated (2 sigma) provides a dating range from , with a greater probability of the period (53.5%). The feature has been registered as an ancient site, Långared 2:2. Figure 9. Wooden pole interpreted as part of a permanent fishing trap (Långared 2:2). Photo Staffan von Arbin. Bohusläns museum. Figur 9. Påle tolkad som del av fast fiske (Långared 2:2). Foto Staffan von Arbin. Bohusläns museum. Långared 2:1 - cultural layers (A2) The results of the visual survey and test trenches have led to the extension of the Långared 2:1 in the form of cultural layers (A2) which are associated with the castle settlement. The test trenches revealed whole bricks, wooden chips, and coal fragments (appendix 3). The finds and objects located during the visual inspection are also within the extent of the cultural layer (appendix 1). The layer is thin and is present throughout the extent of the survey area.

14 12 Bohusläns museum 2010:53 Documented finds A concreted metal object, F1, was located in the western extent of the survey area and measured 28 centimeters in length and 8 centimeters in width (figure 11). It is thought to be part of the cultural layer associated with Loholmen castle, Långared 2:1. Two ceramic shards from a redware jug, F2, were recovered during a visual survey dive to the northwest of the survey area (figure 12). Of the larger fragment a part of the rim, the entire handle and a portion of the shoulder remained in tact, while the smaller shard formed a part of the rim. The jug has a zig-zag pattern on the shoulder with circular decorations at the corners of the pattern. Similar types of ceramic finds can assert a preliminary date of to the jug (cf Wahlöö 1976). An eroded oak timber, F3, was located near the centre of the search area (figure 13). It is thought to have been a construction timber, possi bly from the bridge construction Långared 330:1. The timber measured two meters long, eighteen centimeters at its widest part, and circa nine centimetres thick. Figure 10. Wooden pole interpreted as part of a permanent fishing trap (Långared 2:2). Photo Staffan von Arbin. Bohusläns museum. Figur 10. Påle tolkad som del av fast fiske (Långared 2:2). Foto: Staffan von Arbin. Bohusläns museum. Figure 11. Concreted metal object. Photo Staffan von Arbin. Bohusläns museum. Figur 11. Korroderat metallföremål. Foto Staffan von Arbin. Bohusläns museum. Figure 12. Fragments of a redware jug (F2). Photo Delia Ní Chíobháin. Bohusläns museum. Figur 12. Fragment av kanna i äldre rödgods (F2). Foto Delia Ní Chíobháin. Bohusläns museum.

15 Loholmen 13 Discussion The cultural layers discovered within the investigation area contain artefacts which are contemporaneous with Loholmen castle, in particular the brick finds, worked timbers and the ceramic shards which can be dated to the period that Loholmen castle was in use. Since the history of the castle is not very well known, the layers can contribute to the present knowledge of the site. While permanent fishing traps have been used over a long period of time throughout history, few sites have been investigated archaeologically. However, Bohusläns museum has conducted research on permanent fishing traps in several locations around Sweden including Åsunden lake, Ulricehamns kommun (von Arbin 2006), in the sound outside Arvika (von Arbin & Wallbom 2004) and in the estuary of the Tidan river in Mariestads kommun (von Arbin & Lindström 2005), which have all been dated to the medieval period. Archaeological excavations conducted in Motala river in Östergötland have revealed fishing traps from the early medieval period and modern times (von Arbin, forthcoming). The varying nature of fishing trap construction is dependant on the environment in which they are placed but all share the same characteristics of a barrier construction with a pointed entrance, leading the fish into some form of trapping chamber (Eriksson 1993). The condition of most remains however are too eroded to identify their precise design but fishing traps from the historical period could potentially be compared to contemporary written sources (Gainsford 2009). While the 14 C-date from one of the stakes of is not contemporary with the use of Loholmen castle, the remains consist of an ancient monument and contribute to the growing knowledge of this type of maritime feature. Figure 13. Eroded oak timber (F3). Photo Staffan von Arbin. Bohusläns museum. Figur 13. Eroderat ektimmer (F3). Foto Staffan von Arbin. Bohusläns museum. Conclusion and recommendations The archaeological survey revealed further evidence of cultural remains in the vicinity of Loholmen and have resulted in the extension of the Långared 2 site. The discovery of the redware ceramic finds positively date the cultural layer to the s, the earlier occupation period of the castle. The later date range provided for the permanent fishing trap ( ) indicates continued use of the area up to the modern era. As the visual survey and test trenches revealed remains of low archaeological importance in the immediate area of the proposed jetty site, Bohusläns museum have no archaeological comments to make on the proposals.

16 14 Bohusläns museum 2010:53 Referenser Litteratur von Arbin, S På Åsundens botten. Arkeologisk utredning inför planerade vattenverksamheter Ulricehamns stad och kommun. Bohusläns museum Rapport 2006:43. Uddevalla. von Arbin, S. & Wallbom, B Arkeologisk utredning: Del av sundet. Arvika socken och kommun, Värmlands län. Bohusläns museum Rapport 2004:44. Uddevalla. von Arbin, S & Lindström, J I Tidans mynning medeltida fiskeanläggningar och en 1800-talspråm. Bohusläns museum Rapport 2005:60. Uddevalla. von Arbin, S. (i tryck). Motala kungsfiske fiskeplats med kontinuitet. Bottnisk kontakt XIII. Båtdokgruppen. Skärhamn. Bergstrand, T Loholmens borgruin Raä 2, Långareds socken, Alingsås kommun. Dendrokronologiska dateringar. Bohusläns museum Rapport 2003: 31. Uddevalla. Dahrén, B. & Fransson, S Sägenomspunna Loholmen. Marinarkeologisk tidskrift 1/2004, (7 9). Dykeriarbete. AFS 1993:57. Arbetarskyddsstyrelsen. Stockholm. Ekre, R Västergötlands medeltidsborgar. Borgar från forntid och medeltid i Västsverige. Arkeologi i Västsverige 5 ( ). Göteborgs arkeologiska museum. Gainsford, M Spillvattenledning i Alingsås, Gärdska ström, Gärdsken, Forsån och Lilla Färgen. Frivillig arkeologisk utredning, Alingsås socken och kommun. Bohusläns museum Rapport 2009:34. Uddevalla. Wahlöö, C Keramik I svenska fynd. Arcaeologica Lundensia. Investigationes de antiqvitatibus urbis Lundae VI. Lund.

17 Loholmen 15 Otryckta källor Eriksson, M Fasta fisken. B-uppsats i arkeologi. Arkeologiska institutionen. Stockholms universitet.

18 16 Bohusläns museum 2010:53 Tekniska och administrativa uppgifter Lst dnr: Västarvet dnr: NOK Västarvet pnr: Fornlämningsnr: Långared 2:1, 2:2 Län: Kommun: Socken: Fastighet: Västra Götalands län Alingsås Långared Vattenområde nordväst om Loholmen Ek. karta: 7C 8b Läge: X: , Y: Vattendjup: 0-3 meter Koordinatsystem: RT90, 2,5 gon V Uppdragsgivare: Ansvarig institution: Projektledare: Fältpersonal: Konsulter: Antens Kommunikationsmuseum Bohusläns museum Staffan von Arbin Staffan von Arbin (Bohusläns museum) Delia Ní Chióbháin (Bohusläns museum) Roland Peterson (Vänermuseet) Ångströmlaboratoriet, Uppsala Studio Västsvensk Konservering, Göteborg Fältarbetstid: 11 augusti 2010 Arkeologtimmar: 24 Undersökt yta: 1500 m 2 Arkiv: Fynd: Bohusläns museums arkiv Keramikkannan (F2) kommer efter konservering att överlämnas till Lödöse museum

19 Loholmen 17 Appendices Appendix 1. Plan över undersökningsområdet med provgropar, anläggningar och fynd markerade. Utsnitt ur GSD-Fastighetskartan, blad 7C 8b. Skala 1:1500. Godkänd ur sekretessynpunkt för spridning. Lantmäteriet Dnr /2371 Appendix 2a. Resultat av 14 C -analys av trä från Alingsås kommun, Västra Götalands län. Ångströmlaboratoriet. Uppsala universitet. Labnummer Ua Göran Possnert och Ingela Sundström Appendix 2b. Resultat av 14 C -analys av trä från Alingsås kommun, Västra Götalands län. Ångströmlaboratoriet. Uppsala universitet. Labnummer Ua Göran Possnert och Ingela Sundström Appendix 3. Provgropar och fynd Appendix 4. Inmätta fynd

20 Appendix 1. Plan över undersökningsområdet med provgropar, anläggningar och fynd markerade. Utsnitt ur GSD- Fastighetskartan, blad 7C 8b. Skala 1:1500. Godkänd ur sekretessynpunkt för spridning. Lantmäteriet Dnr /2371

21 Appendix 2a. Resultat av 14 C -analys av trä från Alingsås kommun, Västra Götalands län. Ångströmlaboratoriet. Uppsala universitet. Labnummer Ua Göran Possnert och Ingela Sundström

22 Appendix 2b. Resultat av 14 C -analys av trä från Alingsås kommun, Västra Götalands län. Ångströmlaboratoriet. Uppsala universitet. Labnummer Ua Göran Possnert och Ingela Sundström

23 Appendix 3. Provgropar och fynd Provgrop ID Vattendjup/meter Beskrivning Fynd PG x 50 cm stor, 50 cm djup Träflis, tegelsten, träkolsfragment PG x 50 cm stor, 50 cm djup Inga fynd PG x 50 cm stor, 50 cm djup Tegelfragment, träkolsfragment, små träfragment

24 Appendix 4. Inmätta fynd ID Vattendjup/meter Beskrivning Koordinator (x/y) RT 90 2,5 gon V F1 2 Metallföremål / F2 2 Keramik / F3 2 Konstruktionstimmer /

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