Canadian Ice Caps as Sources of Environmental Data
Seven surface-to-bedrock ice cores, varying from 129 to 337 m in length, have been recovered from Canadian high Arctic ice caps since 1964 (Table 1 and Figure 1). While one (Meighen Island) consists entirely of Holocene ice, the others (Devon and Agassiz ice caps) cover time spans of 100,000 years,...
| Main Authors: | , , , |
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| Format: | Text |
| Language: | English |
| Published: |
1992
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| Online Access: | http://www.dtic.mil/docs/citations/ADP007342 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADP007342 |
| Summary: | Seven surface-to-bedrock ice cores, varying from 129 to 337 m in length, have been recovered from Canadian high Arctic ice caps since 1964 (Table 1 and Figure 1). While one (Meighen Island) consists entirely of Holocene ice, the others (Devon and Agassiz ice caps) cover time spans of 100,000 years, similar to those from Greenland. Our relatively thin ice caps provide simple drilling conditions but give records of various parameters from several holes down a flow line. Comparison of these records continues to provide information on signal-to-noise ratios and ice cap rheology. The major disadvantage of thin ice caps is poor resolution in ice more than 5000 to 10,000 years old. This is offset, however, by the relative ease of retrieval of significant numbers of pollen grains from all levels in the ice. Thus we have been able to use pollen as a paleoenvironmental tool leading, for example, to identification of basal ice layers as Sangamonian in age. Similarly, although annual melting of snow at the surface precludes the possibility of using ice cores for gas analysis, the persistence of variable melt layer concentrations through the Holocene ice has given a continuous melt layer record showing gradual deterioration of summer climate from a warm peak 8000 to 9000 years ago, to a cold minimum 200 years ago. |
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