Michelle A. Chaput & Konrad Gajewski · 0 15 30 0 2 4 6 8 10 0 15 30 0 2 4 6 8 Arctic 0 35 70 0 2 4...
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0 15 30 0 2 4 6 8 10 0 15 30 0 2 4 6 8 Arctic 0 35 70 0 2 4 6 8 10 12 0 45 90 0 1 2 3 4 5 6 0 35 70 0 2 4 6 8 10 12 Michelle A. Chaput & Konrad Gajewski Laboratory for Paleoclimatology and Climatology, University of Ottawa ([email protected]) INTRODUCTION The Canadian Archaeological Radiocarbon Database 1 (CARD) contains 36,000 14 C dates from Canada and the U.S. derived from archaeological and paleoecological material dating between 0 and 48,000 calibrated years BP. Here, we assess at a regional scale the quality of the CARD and identify problematic data by analyzing 663 14 C dates from Québec. We relate the results to a climate reconstruction for boreal Canada 2 to see whether archaeological and paleoecological data together provide an indication of human-climate dynamics. Lichen- Woodland Boreal Temperate- Continental Temperate- Montane Figure 1 (above). Histograms of the frequency of 14 C dates in 5 ecoregions in Québec. Figure 2 (right). 14 C sites based on ecoregion. An anomalous date (8,428 cal BP) is circled in orange. ARCHAEOLOGICAL DATES CARD sites are located mainly around lakes and coastal regions. All ecoregions contain the most dates between 1,000 - 3,000 cal BP, gradually decreasing towards the past. Taphonomic loss has not been accounted for and is likely emphasizing the lack of earlier dates. One anomalous date was identified in the Arctic (8,428 cal BP) where glacial ice remained until 7,000 cal BP, although 79 dates have been labelled in the CARD as “anomalous”. Anomaly HOLOCENE CLIMATE RECONSTRUCTION Time (yrs BP) Figure 3. July and January temperature and precipitation anomalies for Boreal Québec based on 25 pollen records 2 . At a regional scale, using 14 C dates as proxy for population density allows for a few generalizations to be made. Between 9 - 7 ka cal BP, when temperature and precipitation are high, the frequency of boreal dates increases. Population is likely increasing as new land becomes available. Temperature, precipitation and 14 C dates gradually increase towards the present. Paleoindians migrated into northern Québec following the retreat of the ice sheet but maintained a constant presence in the south throughout the Holocene. REFERENCES 1 Gajewski, K., Munoz, S., Peros, M., Viau, A., Morlan, R., and Betts, M. 2011. The Canadian Archaeological Radiocarbon Database (CARD): archaeological radiocarbon dates in North America and their paleoenvironmental context. Radiocarbon, 53: 371-394. 2 Viau, A., and Gajewski, K. 2009. Reconstructing millennial-scale, regional paleoclimates of boreal Canada during the Holocene. Journal of Climate, 22: 316-330. Frequency of Dates Age (cal yrs BP)
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Michelle A. Chaput & Konrad Gajewski Laboratory for Paleoclimatology and Climatology, University of Ottawa ([email protected])
INTRODUCTION The Canadian Archaeological Radiocarbon Database1 (CARD) contains 36,000 14C dates from Canada and the U.S. derived from archaeological and paleoecological material dating between 0 and 48,000 calibrated years BP. Here, we assess at a regional scale the quality of the CARD and identify problematic data by analyzing 663 14C dates from Québec. We relate the results to a climate reconstruction for boreal Canada2 to see whether archaeological and paleoecological data together provide an indication of human-climate dynamics.
Lichen- Woodland
Boreal Temperate- Continental
Temperate- Montane Figure 1 (above). Histograms
of the frequency of 14C dates in 5 ecoregions in Québec.
Figure 2 (right). 14C sites based on ecoregion. An anomalous date (8,428 cal BP) is circled in orange.
ARCHAEOLOGICAL DATES CARD sites are located mainly around lakes and coastal regions. All ecoregions contain the most dates between 1,000 - 3,000 cal BP, gradually decreasing towards the past. Taphonomic loss has not been accounted for and is likely emphasizing the lack of earlier dates. One anomalous date was identified in the Arctic (8,428 cal BP) where glacial ice remained until 7,000 cal BP, although 79 dates have been labelled in the CARD as “anomalous”.
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HOLOCENE CLIMATE RECONSTRUCTION
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Figure 3. July and January temperature and precipitation anomalies for Boreal Québec based on 25 pollen records2.
At a regional scale, using 14C dates as proxy for population density allows for a few generalizations to be made. Between 9 - 7 ka cal BP, when temperature and precipitation are high, the frequency of boreal dates increases. Population is likely increasing as new land becomes available. Temperature, precipitation and 14C dates gradually increase towards the present. Paleoindians migrated into northern Québec following the retreat of the ice sheet but maintained a constant presence in the south throughout the Holocene.
REFERENCES 1Gajewski, K., Munoz, S., Peros, M., Viau, A., Morlan, R., and Betts, M. 2011. The Canadian Archaeological Radiocarbon Database (CARD): archaeological radiocarbon dates in North America and their paleoenvironmental context. Radiocarbon, 53: 371-394. 2Viau, A., and Gajewski, K. 2009. Reconstructing millennial-scale, regional paleoclimates of boreal Canada during the Holocene. Journal of Climate, 22: 316-330.
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