The future preservation of a permanently frozen kitchen midden in Western Greenland

TY - JOUR

T1 - The future preservation of a permanently frozen kitchen midden in Western Greenland

AU - Hollesen , Jørgen

AU - Jensen, Jan Bruun

AU - Matthiesen, Henning

AU - Elberling, Bo

AU - Lange, Hans

AU - Meldgaard, Morten

N1 - CENPERM[2012]

PY - 2012

Y1 - 2012

N2 - Archaeological materials may be extraordinarily well preserved in Arctic areas, where permanently frozen conditions in the ground slow down the decay of materials such as wood, bone, flesh, hair, and DNA. However, the mean annual air temperature in the Arctic is expected to increase by between 2.5 to 7.5° C by the end of the twenty-first century. This may have a significant warming effect on the soil and could lead to permafrost thaw and degradation of currently frozen archaeological remains. Here we present a four-year monitoring and research project taking place at Qajaa in the Disko Bay area in West Greenland. Qajaa is a large kitchen midden, containing frozen remains from 4000 years of inhabitation, from when the first Palaeo-Eskimos entered Greenland, until the site was abandoned in the eighteenth century. The purpose of the project is to investigate current preservation conditions through field and laboratory measurements and to evaluate possible threats to the future preservation. Preliminary results show that the archaeological material at Qajaa is still very well preserved, but some microbial decay is observed in the exposed wooden artefacts that thaw every summer. Maximum temperatures are above 0° C in the upper 40-50 cm of the midden and between 0 and ?2° C down to 3 m depth. Thereby the permafrost may be vulnerable to quite small increases in air temperatures. Laboratory measurements show that the decay of the archaeological wood in the midden is temperature-dependent, with rates increasing 11-12% every time the soil temperature increases 1° C. Moreover, the soil organic material produces heat when decomposed, which could have an additional warming effect on the midden. At the moment the water or ice content within the midden is high, limiting the subsurface oxygen availability. Threats to the future preservation are related to further thawing followed by drainage, increased oxygen availability, microbial decay of the organic material, and heat production.

AB - Archaeological materials may be extraordinarily well preserved in Arctic areas, where permanently frozen conditions in the ground slow down the decay of materials such as wood, bone, flesh, hair, and DNA. However, the mean annual air temperature in the Arctic is expected to increase by between 2.5 to 7.5° C by the end of the twenty-first century. This may have a significant warming effect on the soil and could lead to permafrost thaw and degradation of currently frozen archaeological remains. Here we present a four-year monitoring and research project taking place at Qajaa in the Disko Bay area in West Greenland. Qajaa is a large kitchen midden, containing frozen remains from 4000 years of inhabitation, from when the first Palaeo-Eskimos entered Greenland, until the site was abandoned in the eighteenth century. The purpose of the project is to investigate current preservation conditions through field and laboratory measurements and to evaluate possible threats to the future preservation. Preliminary results show that the archaeological material at Qajaa is still very well preserved, but some microbial decay is observed in the exposed wooden artefacts that thaw every summer. Maximum temperatures are above 0° C in the upper 40-50 cm of the midden and between 0 and ?2° C down to 3 m depth. Thereby the permafrost may be vulnerable to quite small increases in air temperatures. Laboratory measurements show that the decay of the archaeological wood in the midden is temperature-dependent, with rates increasing 11-12% every time the soil temperature increases 1° C. Moreover, the soil organic material produces heat when decomposed, which could have an additional warming effect on the midden. At the moment the water or ice content within the midden is high, limiting the subsurface oxygen availability. Threats to the future preservation are related to further thawing followed by drainage, increased oxygen availability, microbial decay of the organic material, and heat production.

U2 - 10.1179/1350503312Z.00000000013

DO - 10.1179/1350503312Z.00000000013

M3 - Journal article

SN - 1350-5033

VL - 14

SP - 159

EP - 168

JO - Conservation and Management of Archaeological Sites

JF - Conservation and Management of Archaeological Sites

IS - 1-4

ER -