Non-invasive dendrochronology success and limitations Aoife Daly

Transkript

1 Non-invasive dendrochronology success and limitations Aoife Daly

2 Larvik Boats, Norway Sampling for dendrochronological analysis

3 Stegeborg Denmark Sampling for dendrochronological analysis

4 Rembrandt s Entombment (Hunterian Glasgow) Photographing the end-grain for dendrochronological analysis

5 Oak anatomy

6 Gokstad project Previous analysis The building of the grave chamber in the Gokstad burial mound was estimated to be AD The felling date for the trees used for the Gokstad Ship was estimated to 890s. No sapwood on the analysed samples. The wood for chamber and ship had grown in the Oslo fjord region (Bonde 1995).

7 DendroCT Gokstad funded by Nordic Culture Fund and Anders Jahre s Humanitarian Foundation. Jan Bill, Oslo University Aoife Daly, Dendro.dk Øistein Johnson, Norwegian Geotechnical Institute Knut Dalen, Norwegian University of Life Sciences

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9 Oseberg samples 6 narrow ring series

10 Oseberg sample 6, images The cut surface Medical CT

11 Oseberg sample 6, first attempt AD653 AD807 Oseberg\Z037003A.D Oseberg\Z037003X.D

12 Oseberg sample 6, 2nd scanning Micro CT The cut surface

13 Oseberg, comparing tree-ring curves AD653 AD807 Oseberg sample 6 from micro-ct Z037003a Oseberg sample 6 conventional measurements Z037003d

14 Oseberg, comparing tree-ring curves AD653 AD807 Oseberg sample 6 from micro-ct Z037003a Oseberg sample 6 conventional measurements Z037003d

15 Direct versus scan DIRECT MEASUREMENT Gokstad z038001a.d MEASUREMENT FROM SCAN Gokstad z038001w.d

16 Direct versus scan DIRECT MEASUREMENT Gokstad z038001a.d MEASUREMENT FROM SCAN Gokstad z038001w.d

17 Method (see Bill et al 2012) Spades from the Tune burial mound

18 0.34mm method

19 Spades from Oseberg, Gokstad and Tune (Bill & Daly 2012) (Photo Bill et al 2012)

20 Sapwood on the scanned images Gokstad ship, plank fragment

21 Gokstad Ship, dating (Daly, in press) Gokstad ship bord q102 Z038027a after AD 744 q033 Z038014a after AD 796 prøve 13 z038005a after AD Z038015a after AD Z038031a after AD Z038012a after AD 875 v Z038029a after AD 877 tværbjælke C10384.l Z038023a after AD 884 bord tree1 q027 Z038009a after AD 884 prøve 23 z038006a after AD 884 bord tree2 q097 Z038016a after AD 845 prøve 21 z038002a after AD 845 prøve 22 z038003a after AD 845 q096 z038008a after AD 845 bord tree6 q071 Z038026a after AD 864 prøve 18 z038004a&b after AD Z038901a after AD 864 prøve 12 z038007a after AD 864 bord tree8 029 Z038033a AD b Z038010a AD a Z038011a AD Gokstad Ship Bed etc. winter 895-6

22 Photos from Gokstad boat G3 provenance? (Daly, in press) Gokstad båd G3 G3 bord G3 7a Z038109a after AD 677 G3-174 Z after AD 752 G3 199b Z038107a after AD 811 G3 1kort Z038115a after AD 827 G3 18 Z038112a after AD 852 G3 17 Z038111b after AD 864 G3 bord tree11 G3-34 z038104a AD G 3-15 z038101a AD G3 bord tree12 G3 97a Z after AD 780 G3-8 z after AD 780 G3 bord tree13 G3 1lang Z038114a after AD 741 G3-1kort Z038108a after AD 741 G3 reparation? G 3-83 z038102a AD Gokstad Ship Bed etc. winter 895-6

23 Gokstad, boat G3 Building Repair phase Filenames - - z0381m03 z038102a - start Dates AD 504 AD dates End AD 886 AD 888 Z037M001 AD 549 AD ,55 - Oseberg ship (Daly unpubl.) Z0382M01 AD 548 AD 895 4,70 11,51 Gokstad inventory big group (Daly 2011b) Indbrudslag gr3 AD 550 AD 925-7,56 Break-in group 3 (Daly 2011a) Z0371M01 AD 536 AD 833-5,99 Oseberg grave chamber (Daly upubl.) N054M001 AD 666 AD 967 3,73 5,76 Klåstad (Eriksen 1993) Z038ship AD 578 AD 876 3,64 5,72 Gokstad Ship (Daly 2011b) Z055M001 AD 716 AD 889-5,27 Tune ship (Daly upubl.) KAUPANG AD 518 AD 862 4,89 4,73 Kaupang (Bonde 2007) The timbers used to build boat G3 from the Gokstad burial are dating with tree-ring curves from the Oseberg Ship. The Oseberg ship is made from oaks that grew in West Norway (Bonde & Stylegar 2009) so we can conclude that the small Boat G3 also comes from West Norway. A single plank from G3 however dates with tree-ring data from the region around Oslo Fjord (Daly, in press).

24 Identifying bark edge on the scanned images Gokstat inventory, bedpost fragment Gokstad ship, bedpost fragment

25 Bedpost bark edge Bed etc. winter 895-6

26 Bed post from Gokstad. Many of the wooden objects from Gokstad can only be dated dendrochronologically thanks to the development of a non-destructive sampling method.

27 The plundering (Bill & Daly 2012) The Break-in, all mounds Gokstad spade C10421.e Z038836a træ 3 AD C10421b Z038834a after AD 824 C10421d Z038833a after AD 868 C10421.f Z038837a after AD 912 C10421.h Z038835a after AD 939 Oseberg stretcher C Z037216A after AD a c Oseberg spade * * AD 600 AD 750 AD 900 Z037207A after AD 938 Z037208A after AD 944 z after AD 951 Z037209A after AD Z AD Z037212A after AD Z037214A after AD Z037210A after AD z after AD z037205a after AD Z after AD Z after AD 933 Tune spade C23838 o Z055201A AD C23838 o Z055202x AD Oseberg grave chamber summer 834 * * Gokstad Ship Gokstad bed etc. winter Tune c. 910 Fig 1. De norske vikingeskibsgrave, dendrokronologisk datering af spaderne og båredele fra Oseberg, Gokstad og Tune gravhøje.

28 The plunderings, correlation (Daly 2011a) Filenames - - all Long Group 3 Shorter Group 2 - start Dates AD 550 AD 550 AD dates End AD 945 AD 925 AD 945 Z0382M01 AD 548 AD ,98 13,93 9,61 Gokstad inventar big group (Daly 2011b) oslo fjord AD 536 AD ,67 15,00 9,17 oslo fjord (Gokstad skib, Oseberg gravkammer, Tune skib, Klåstad skib) (Daly upubl.) Z0371M01 AD 536 AD ,42 12,13 6,02 oseberg gravkammer (Daly upubl.) Z055M001 AD 716 AD ,13 7,60 9,94 Tune ship (Daly upubl.) 00695M01 AD 674 AD Roskilde vrag 6 (Bonde 1997) KAUPANG AD 518 AD 862 8,88 7,66 6,38 Kaupang (Bonde 2007, 282) Z036M001 AD 666 AD 967 8,29 7,35 6,77 Klåstad (Daly upubl.) N054M001 AD 666 AD 967 8,13 6,92 6,75 Klåstad (Eriksen 1993) Z038ship AD 578 AD 876 7,39 7,59 9,26 Gokstad ship (Daly 2011b) Z0382M02 AD 713 AD 876 5,59 4,96 4,04 Gokstad inventar small grp. (Daly 2011b) 9M BC AD ,68 5,02 3,53 Jylland/Fyn (Nationalmuseet) Z037M001 AD 549 AD 815 3,60-3,42 Oseberg ship (Daly upubl.) Tabel 2. De norske vikingeskibsgrave, synkroniseringen mellem middelkurverne for spaderne og båredele fra Oseberg, Gokstad og Tune gravhøje og diverse kurver fra Nordeuropa. Kilden til kurverne er givet.

29 The plundering, t-values (Bill & Daly 2012) * *

30 Gokstad spade Z038837a Oseberg stretcher plank Z037216A

31 Modern oaks around Oslo Fjord (tree-ring data Kjeld Christensen, pers comm)

32 The plundering (Bill & Daly 2012) The Break-in, all mounds Gokstad spade C10421.e Z038836a træ 3 AD C10421b Z038834a after AD 824 C10421d Z038833a after AD 868 C10421.f Z038837a after AD 912 C10421.h Z038835a after AD 939 Oseberg stretcher C Z037216A after AD a c Oseberg spade * * AD 600 AD 750 AD 900 Z037207A after AD 938 Z037208A after AD 944 z after AD 951 Z037209A after AD Z AD Z037212A after AD Z037214A after AD Z037210A after AD z after AD z037205a after AD Z after AD Z after AD 933 Tune spade C23838 o Z055201A AD C23838 o Z055202x AD Oseberg grave chamber summer 834 * * Gokstad Ship Gokstad bed etc. winter Tune c. 910 Fig 1. De norske vikingeskibsgrave, dendrokronologisk datering af spaderne og båredele fra Oseberg, Gokstad og Tune gravhøje.

33 Power politics? Storhaug Grønhaug Oseberg Gokstad Aggersborg Fyrkat Ravning Enge bridge Jelling Nonnebakken Trelleborg Borgeby Trelleborg the plundering after 953 Storhaug ship 771 Grønhaug ship 780 Oseberg ship 820 burial 834 Gokstad ship bed Jelling 960s Ring fortress & bridge 980s 0 burial 779 Boat G burial

34 The Jelling Stone Harald King had these stones made after Gorm his father and after Thyra his mother that Harald who won all Denmark and Norway and made the Danes Christian Dating c. 960s

35 literature Bill, J. & Daly, A., The plundering of the ship graves from Oseberg and Gokstad an example of power politics? Antiquity, 86, Bill, J., Dalen, K.S., Daly, A. og Johnsen, Ø., Dendro CT dendrochronology without damage. Dendrochronologia 30 (2012) Bonde, N Dendrochronological dating of the Viking age ship burials at Oseberg, Gokstad and Tune, Norway. In: A. Sinclair, E. Slater & J. Gowlett (Eds) Archaeological Sciences Oxford, Bonde, N., Præliminær dendrokronologisk undersøgelse af seks skibsvrag fra Roskildes gamle havneområde. Nationalmuseets Naturvidenskabelige Undersøgelser rapport , Copenhagen. Bonde, N., Dendrochronological dates from Kaupang. In: Dagfinn Skre (ed.), Kaupang in Skiringssal, Kaupang excavation project publication series volume 1. Aarhus University Press, Bonde, N. and Stylegar, F.-A. (2009). Fra Avaldsnes til Oseberg. Dendrokronologiske undersøkelser av skipsgravene fra Storhaug og Grønhaug på Karmøy. Viking, LXXII, Daly, A., Dendrokronologisk undersøgelse af skibsvrag fra Vejdyb udfor Hals, Aalborg Amt. Nationalmuseets Naturvidenskabelige Undersøgelser rapport 12, 1997, København. Daly, A., Timber, Trade and Tree-rings. A dendrochronological analysis of structural oak timber in Northern Europe, c. AD 1000 to c. AD Ph.D. thesis submitted February 2007, University of Southern Denmark. Daly, A. 2011a. De norske vikingeskibsgrave, indbrudslag. Dendro.dk report 6:2011, Brønshøj. Report prepared for the Museum of Cultural History, Oslo. Daly, A. 2011b. De norske vikingeskibsgrave, Gokstad. Dendro.dk report 9:2011, Brønshøj. Report prepared for the Museum of Cultural History, Oslo. Daly, A., in press. Exploring the Norwegian Viking ship burials through non-destructive dendrochronology. In Jan Bill ed. Returning to Gokstad: The art and the science of revisiting monumental burials in Scandinavia, Aarhus University Press. Eriksen, O.H., Dendrokronologisk undersøgelse af skibsvrag fra Klåstad, Norge. Nationalmuseets Naturvidenskabelige Undersøgelser rapport , Copenhagen.

36 Conclusion and credits Methods Non-invasive dendrochronology and provenance determination high tech to low tech. But I m not quite ready to sell my chain-saw yet! :o) Credits DendroCT Jan Bill & Nordic Culture Fund and Anders Jahre s Humanitarian Foundation.