Hugh M. French

Permafrost on the Tibet Plateau, China

Abstract The Tibet Plateau represents a unique permafrost environment, being a result of high elevation caused by land uplift in the order of 3000 m over the last 2 million years. Under present climatic conditions, the lower altitudinal limit of permafrost in the north is at ≈4200 m a.s.l., which means that if the Plateau were 1000 m lower than present, there would be hardly any permafrost. The permafrost is ice-poor, because during the Quaternary, the area was unglaciated and little water was available for the formation of massive ground ice. Furthermore, todays climate is arid and little moisture is available for segregated and pore ice formation. As a result, mid-portion desiccation of the active layer does not occur to the same extent as in high latitudes. Permafrost temperature on the Plateau depends mainly upon altitude and varies irregularly with latitude. Permafrost is warm and thin compared with high latitude (polar) permafrost in both North America and Russia, and thus more sensitive to changes in climate and surface conditions. A recent warming trend in ground temperature has been monitored, and, if maintained, permafrost will become relict within the next ca. 150 years. Permafrost features are few due to the arid environment. Many of the pingos on the Plateau are genetically associated with faults, and therefore of the open-system type. Faults are the most powerful factor disturbing the thermal regime of the plateau permafrost.

Frozen Ground Phenomena in the Vicinity of Terra Nova Bay, Northern Victoria land, Antarctica: A Preliminary Report

Frozen ground phenomena in the Northern Foothills, Northern Victoria Land, Antarctica, include large–scale polygons, 15–20 m in diameter, and small frost mounds, 1–5 m high. The polygons are most widespread on terrain formed upon Younger Drift and are usually surrounded by interpolygon furrows or troughs, 10–30 cm deep and 10–100 cm wide. The troughs contain shallow wedges of sandy gravel (sand wedges) near the surface but excavations into underlying permafrost indicate that small ice wedges or ice veins are locally present. Field and anecdotal evidence suggest that thermal contraction cracking is active under todays climate. Frost mounds occur in association with a number of perennially frozen lakes in the region. In most cases they appear related to frost and icing blister activity caused by the episodic injection of free water from below. The debris–covered nature of the centre of Enigma Lake is best explained in terms of basal ice accretion beneath the lake–ice cover.

Canada's cold environments

Low temperatures, wind-chill, snow, sea ice, and permafrost have been primary characteristics of Canadas northern and alpine environments during the past two million years. The evolution of Canadas cultural landscapes, the processes of settlement of rural areas, and the present interaction of Canadian industrial society with its biophysical environment are all deeply influenced, directly or indirectly, by the frigidity of the greater part of the country. The phenomenon of global warming, if it occurs, will lessen this coldness, but its impact on temperature extremes, sea ice regimes, vegetation, snow distribution, permafrost, glaciers, lakes, rivers, and mountain hazards are all the subject of intensive research -- the highlights of which are reviewed in Canadas Cold Environments.

Permafrost in the Gruve-7 mine, Adventdalen, Svalbard

Bedrock temperatures were measured over a 12-month period (June 2003–July 2004) at six sites within the Gruve-7 coal mine in the Adventdalen valley, near Longyearbyen (78°N), Svalbard. One site lies 290 m beneath the Foxfonna ice cap, where stable near 0°C conditions were recorded throughout the year. This site is close to the inferred base of permafrost. Other sites at bedrock depths between 35 m and 235 m beneath both glacier-covered and ice-free terrain have mean annual values between −1.2°C and −4.9°C, and annual amplitudes between 0.5°C and 4.5°C. The lowest mean annual ground temperatures (MAGT) of −5.8°C is measured at a depth of c.6 m from the ground surface, and this site is thought to be close to the base of the bedrock active layer. The 3-dimensional nature of the permafrost body is indicated by the fact that the higher permafrost temperatures occur at deeper locations within the massif below the Foxfonna ice cap and glacier, while the lowest temperatures occur where the mine extends beneath ice-free terrain.

Periglacial geomorphology in North America: current research and future trends

Periglacial geomorphology in North America is a rigorous branch of process geo morphology with important applied applications. Since frost action and permafrost are central themes, periglacial geomorphology must be regarded as part of the sci ence of geocryology. Current research problems include the cryogenic weathering of bedrock, frost heave and ice segregation, the nature and origins of ground ice, and active layer processes.

LAKE‐ICE BLISTERS, TERRA NOVA BAY AREA, NORTHERN VICTORIA LAND, ANTARCTICA

Abstract. Ice blisters, typically 0.2–0.8 m high and 5–20 m long, develop annually on perennially frozen lakes in Northern Victoria Land. They are believed to be caused by hydrostatic pressures generated through progressive freezing of solute‐rich water beneath the lake‐ice cover during winter. Lake‐ice blisters in the study area differfrom icing blisters described from the northern hemisphere. The latter are caused by hydraulic pressures and are found at locations such as river beds or spring sites on sloping terrain. The Antarctic lake‐ice blisters reflect the occurrence of dry‐based perennially frozen lakes with high salt contents in an extremely cold and arid environment.

Ground ice in the Northern Foothills, northern Victoria Land, Antarctica

Abstract This progress report classifies the different types of ground-ice bodies that occur in the Northern Foothills, northern Victoria Land, Antarctica. Oxygen isotope variations are presented, but interpretation is kept to a minimum pending further investigations. Surface ice, as distinct from moving glacier ice, occurs in the form of widespread buried (‘dead’) glacier ice lying beneath ablation (sublimation) till, together with perennial lake ice, snow banks and icing-blister ice.’Dry’ permafrost is uncommon, and interstitial ice is usually present at the base of the active layer and in the near-surface permafrost. This probably reflects the supply of moisture from the Ross Sea and limited sublimation under today’s climate. Intrusive ice occurs as layers within perennial lake-ice covers and gives rise to small icing blisters. Small ice wedges found beneath the furrows of high-centered polygons appear to agree with the model of sublimation-till development proposed by Marchant and others (2002).

Periglacial geomorphology and permafrost

The move into a new decade provides an excuse here for speculation as to future trends and developments in periglacial geomorphology. To do this, it is necessary to characterize progress during the past decade and place the developments of the 1970s in their historical perspective. The last decade saw the final disappearance of the mystique surrounding the ’uniqueness’ of the periglacial environments. Instead, it

Albert Pissart and his role in the study of periglacial environments (Albert Pissart et son rôle dans l'étude des millieux périglaciaires)

On the occasion of his retirement from the University of Liege, a group of colleagues summarize the main achievements and activities in periglacial research of Albert Pissart. He is one of the few periglacial geomorphologists who has (1) successfully studied both Pleistocene phenomena and present day processes, (2) undertaken palaeogeographic reconstructions, and (3) carried out numerous experimental and laboratory studies into the effects of cold climates upon rocks and landforms.

NORTH AMERICAN PERIGLACIAL GEOMORPHOLOGY AS A BRANCH OF GEOCRYOLOGY: A BRIEF HISTORY

Permafrost studies first developed as part of the science of geocryology in Russia in the early part of the 20th century. Periglacial geomorphology emerged in the 1950s as a branch of a European-dominated climatic geomorphology. Since then, periglacial geomorphology in North America has become increasingly concerned with permafrost-related process studies and is now viewed by some as a branch of geocryology. The recent development of North American cryostratigraphy allows inferences to be made regarding paleoenvironmental conditions while traditional Pleistocene-oriented periglacial geomorphology has been largely replaced by Quaternary science. The danger exists that North American periglacial geomorphology will cease to be a recognizable sub-branch of geomorphology.