Elevated tritium concentrations in ice veins and wedges recently exposed near Mayo, Yukon Territory, indicate that these features have formed or recracked from time to time during the past thirty years. The mean annual air temperature at Mayo is −4.0°C. Therefore, these features are active in an environment that conventionally would be regarded as too warm for thermal contraction cracking and ice‐wedge development. Periodic cracking is probably related to below‐normal winter air temperatures. Such conditions are not readily apparent in long‐term climatic statistics. It follows that many ice‐wedges whose casts are preserved in the geologic record may not have formed under conditions as cold as previously suggested. Copyright

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Permafrost and Periglacial Processes
Department of Geography and Environmental Studies

Burn, C. (1990). Implications for palaeoenvironmental reconstruction of recent ice‐wedge development at Mayo, Yukon territory. Permafrost and Periglacial Processes, 1(1), 3–14. doi:10.1002/ppp.3430010103