Zarys treści. W komentarzu przedstawiono krytyczne uwagi odnośnie do tekstu S. Kędzi. Główne zarzuty polegają na tym, że autor nie rozróżnia badań sezonowego przemarzania od badań permafrostu, utożsamia ujemną średnią roczną temperaturę gruntu z wieloletnią zmarzliną, a także sugeruje, że można dowieść jej obecności metodami innymi niż pomiar temperatury gruntu w ciągu co najmniej dwóch następujących po sobie lat oraz że permafrost może odpowiadać za ruch reliktowego lodowca gruzowego.Słowa kluczowe: wieloletnia zmarzlina, sezonowe przemarzanie gruntu, Tatry.

No abstract

This paper accompanies a map that shows the extent of permafrost in the Northern Hemisphere between 25 and 17 thousand years ago. The map is based upon existing archival data, common throughout the Northern Hemisphere, that include ice-wedge pseudomorphs, sand wedges and large cryoturbations. Where possible, a distinction is made between areas with continuous permafrost and areas where permafrost is either spatially discontinuous or sporadic. The associated mean annual palaeo-temperatures that are inferred on the basis of present-day analogues increase understanding of the possible changes in permafrost extent that might accompany current global warming trends. Areas with relict permafrost and areas that were formerly exposed due to lower sea level (submarine permafrost) are also mapped. Mapping is mostly limited to lowland regions (areas approximately <1000 m a.s.l.). Striking features that appear from the map are (i) the narrow permafrost zone in North America, which contrasts with the broader LPM permafrost zone in Eurasia (that may be related to different snow thickness or vegetation cover), (ii) the zonal extent of former LPM permafrost (that may reflect sea-ice distribution), which contrasts with the present-day pattern of permafrost extent (especially in Eurasia) and (iii) the relatively narrow zones of LPM discontinuous permafrost (that may indicate strong temperature gradients).

The shape and distribution of ice and sediment within frozen ground constitute its cryostructure. Observations on perennially frozen sediments in the Tuktoyaktuk coastlands enable six cryostructures to be identified: (1) structureless, (2) lenticular, (3) layered, (4) reticulate, (5) crustal, and (6) suspended. These cryostructures can be transitional or composite. Five cryofacies types can also be identified according to volumetric ice content and grain size. They can be grouped into cryofacies assemblages. The utility of the descriptive classification of ice-rich sediments is illustrated from a palaeothaw layer at Crumbling Point.La forme et la distribution de glace et sCdiment dans un sol gel6 reprCsentent sa cryostructure. Les observations sur les sMiments perpktuellement gelts dans les terres cbtikres de Tuktoyaktuk permettent de distinguer six types de cryostructure :(1) sans structure, (2) lenticulaire, (3) stratifite, (4) rtticulCe, (5) crustale et (6) suspendue. Les transitions d'un type a l'autre sont possibles, ou les types peuvent Ctre de nature composite. Cinq cryofaci2s peuvent aussi &re identifies selon son volume de glace prCsent et sa granulometrie. Ils peuvent Ctre groupts en assemblages de cryofaciks. L'utilitC d'une classification descriptive de sCdiments incorporant une important quantitk de glace est illustrte par une couche anciennement dCgelCe t i Crumbling Point.[Traduit par la rMaction]Can.