TY - CHAP

T1 - DendroCT - Dendrochronology without damage

AU - Bill, Jan

AU - Daly, Aoife

AU - Johnsen, Øistein

AU - Dalen, Knut S.

PY - 2012

Y1 - 2012

N2 - The paper describes an evaluation of the applicability of computer tomography in archaeological dendrochronology. Two different computer tomographs were tested, a . Siemens Somatom Emotion single slice scanner developed for medical use, and a . Nikon Metrology model . XT H 225 LC, which is an industrial type scanner. Both scanners were tested against air-dried, archaeological oak wood, and more limited experiments were made with waterlogged archaeological oak wood and archaeological oak wood which had been treated with high-molecular polyethyleneglycol as a conservation treatment. After scanning the resulting imagery were measured and analysed for dendrochronology using off-the-shelf software for handling and measuring on the images and the specialist programme DENDRO for the dendrochronological analyses.The results showed that only the industrial scanner produced sufficiently clear imagery to allow for dendrochronological analyses. In the scans it was possible to separate tree-rings down to 0.2. mm width, and it was possible to identify the sapwood-heartwood border when sufficient sapwood rings were present. It was found, however, that a visual inspection of the object was required to distinguish between sapwood and decayed wood. Comparisons between direct measurements of tree-rings and measurements based on CT-imagery revealed no significant differences. The scanning and subsequent dating of more than 90 objects showed that dendrochronological dating based on CT-scanning has a success rate equal to conventional dating, albeit more time consuming.The attempts to scan waterlogged and PEG-impregnated archaeological oak wood were unsuccessful, due to a low degree of contrast between the water/PEG and the preserved wood. The experiments were too limited to exclude, however, that a successful protocol can be developed also for these types of materials. ?? 2012 Istituto Italiano di Dendrocronologia.

AB - The paper describes an evaluation of the applicability of computer tomography in archaeological dendrochronology. Two different computer tomographs were tested, a . Siemens Somatom Emotion single slice scanner developed for medical use, and a . Nikon Metrology model . XT H 225 LC, which is an industrial type scanner. Both scanners were tested against air-dried, archaeological oak wood, and more limited experiments were made with waterlogged archaeological oak wood and archaeological oak wood which had been treated with high-molecular polyethyleneglycol as a conservation treatment. After scanning the resulting imagery were measured and analysed for dendrochronology using off-the-shelf software for handling and measuring on the images and the specialist programme DENDRO for the dendrochronological analyses.The results showed that only the industrial scanner produced sufficiently clear imagery to allow for dendrochronological analyses. In the scans it was possible to separate tree-rings down to 0.2. mm width, and it was possible to identify the sapwood-heartwood border when sufficient sapwood rings were present. It was found, however, that a visual inspection of the object was required to distinguish between sapwood and decayed wood. Comparisons between direct measurements of tree-rings and measurements based on CT-imagery revealed no significant differences. The scanning and subsequent dating of more than 90 objects showed that dendrochronological dating based on CT-scanning has a success rate equal to conventional dating, albeit more time consuming.The attempts to scan waterlogged and PEG-impregnated archaeological oak wood were unsuccessful, due to a low degree of contrast between the water/PEG and the preserved wood. The experiments were too limited to exclude, however, that a successful protocol can be developed also for these types of materials. ?? 2012 Istituto Italiano di Dendrocronologia.

KW - Archaeology

KW - Computer tomography

KW - Non-destructive dendrochronology

KW - Oak

U2 - 10.1016/j.dendro.2011.11.002

DO - 10.1016/j.dendro.2011.11.002

M3 - Book chapter

SN - 11257865

SP - 223

EP - 230

BT - Dendrochronologia

ER -