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The results of a combined geophysical and geomorphological investigation of thermal‐contraction‐crack polygons near Gondwana station (Germany) in northern Victoria Land (Antarctica) are reported. An area of about 20,000 m2 characterized by random orthogonal polygons was investigated using integrated ground penetrating radar, electrical resistivity tomography, geomorphological surveys, and two trench excavations. The polygons are well developed only at elevations higher than 6–7 m above current sea level on Holocene‐age raised beaches. It is concluded that the polygons are composite in nature because the shallow linear depressions that outline the polygons are underlain by fissures that can contain both sandy gravel and foliated ice (i.e., ice wedges) even in the same polygon network and at distances of just a few meters. Unexpectedly, most of the polygons follow the border of the raised beaches and develop in correspondence with stratigraphic layers dipping toward the sea, imaged by ground penetrating radar (GPR) profiles and interpreted as prograding layers toward the present‐day shoreline. [ABSTRACT FROM AUTHOR]

Stephen Taber's early work on ice segregation and frost heaving was far ahead of its time. His laboratory experiments regarding ice segregation led to our current understanding of frost heave by civil and geotechnical engineers building roads and other structures in cold regions. It also laid the foundation for later process‐oriented field studies of cold‐climate geomorphic processes. Taber's 1943 regional monograph on the origin and history of perennially frozen ground in Alaska, published by the Geological Society of America, was the earliest example of regional cryostratigraphy, and pioneered the regional permafrost and Quaternary studies undertaken later by Katasonov, Popov, Mackay, Péwé, Hopkins, and others. An important dimension of Taber's Alaska work was his application of knowledge gained through laboratory experimentation to the interpretation of ground‐ice exposures in the field. While S. W. Muller is widely regarded as the "father" of permafrost studies in North America, Taber is properly viewed as the "progenitor" of cryostratigraphic studies, although he is not yet widely regarded as such. This study uses archival resources to provide historical context regarding the development of Taber's monograph, to investigate details about the review and publication process it underwent, and to explore the question of why it remains undervalued. [ABSTRACT FROM AUTHOR]

During the last 50 ka, cryogenic wedges on the Ordos Plateau formed during three major periods: (i) early local Last Glaciation, ca. 50 ka BP; (iii) local Last Permafrost Maximum(local LPM), 25–19 ka BP; and (v) post‐local LPM, 16–9 ka BP. Cryoturbations mainly formed in the following periods: (ii) pre‐local LPM, 45–30 ka BP and (iv) ~ 20 ka BP. The coldest periods with well‐developed permafrost (i and iii) were most conducive for forming cryogenic wedges. The following periods of warming climate and degrading permafrost favored the formation of cryoturbations. During the local LPM, sand wedges and polygons were well developed and widely distributed on the Ordos Plateau when mean annual air temperatures (MAATs) were approximately 12°C lower than that at present. At ~30 ka BP, MAAT was 6–7°C lower than that at present. Paleoclimate conditions on the Ordos Plateau were reconstructed since 50 ka BP as follows: cold (ca. 50 ka BP) → cool (45–30 ka BP) → very cold (25–19 ka BP) → cool (19–9 ka BP) → intermittent warming until the present day. The amount of precipitation fluctuated, but with a general trend of drying since 50 ka BP. Under the next generally warming climate (after 9 ka BP), permafrost gradually degraded and eventually disappeared from the Ordos Plateau. [ABSTRACT FROM AUTHOR]

This paper presents new field observations that assist in further defining the extent of Last Permafrost Maximum (LPM) permafrost and frozen ground in north China. In that respect, this region is specific by its arid environment and continental position. Bedrock exposures and sand and gravel pits were examined along a south-north transect from southern Ordos as far as the vicinity of Dongsheng District, Ordos City on the Ordos Plateau (North China). Attention focussed upon the recognition of sand-wedge remains and possible cryoturbations. Two types of wedge structures were recognized: type A wedges extend to depths in excess of 3.0 m and are thought to have formed under conditions of continuous permafrost. Type B wedges are restricted to the upper 1.5 m and are thought to reflect discontinuous permafrost and/or deep seasonal frost. OSL dating of wedge infills indicates that type A wedges formed between 23–19 ka and younger type B wedges formed until the early Holocene. It is now possible to delineate a more exact position of the boundary between continuous permafrost and discontinuous permafrost and/or deep seasonal frost on the Ordos Plateau during the LPM. This boundaries occur between Dongsheng and Jinbian at 37°-39°N. • Precise location of southern limit of continuous permafrost during the Last Permafrost Maximum (c.19-23 ka) in north China. • Narrow zone of discontinuous/sporadic permafrost during the Last Permafrost Maximum (c.19-23 ka) in north China. • Permafrost extent in N China at LPM was specific by its aridity, continentality and proximity to the Siberian High Pressure. [ABSTRACT FROM AUTHOR]

Much of the northern interior Yukon was never-glaciated during the Quaternary. It has experienced cold and arid conditions for several millions of years. It represents one of the closest approximations that exist today of a periglacial landscape and provides an opportunity to assess conceptual models of periglacial landscape evolution. The terrain of two upland areas, Eagle Plain and the Barn Mountains foothills, casts doubt upon the widely-assumed rapidity of periglacial landscape modification and suggests that the complete footprint of periglaciation is rarely achieved in upland terrain. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

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). [ABSTRACT FROM AUTHOR]

This paper presents three maps that summarize current knowledge as to the extent of Past permafrost and Relict permafrost in North America at approximately the time of the Last Glacial Maximum ( LGM; c. 25-17 ka BP) and during subsequent deglaciation until c. 10 ka BP. Analysis of the post-1983 literature suggests that the extent of Past permafrost south of the LGM limit was broader in eastern North America and slightly narrower in the Interior Great Plains than previously mapped. The recognition and dating of Relict permafrost in the nonglaciated terrain of the northwestern Arctic suggests that permafrost may be of great antiquity and can persist under changing climatic conditions. The formation of permafrost features during deglaciation suggests that ice-proximal climatic conditions remained cold at least long enough for short-lived permafrost aggradation; a latitudinal gradient is evident in the timing of its development as the Laurentide Ice Sheet retreated. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The permafrost history of the high northern latitudes over the last two million years indicates that perennially frozen ground formed and thawed repeatedly, probably in close synchronicity with the climate changes that led to the expansion and subsequent shrinkage of continental ice sheets. The early stages of the Pleistocene are the least known and the changes that occurred in the Late Pleistocene and early Holocene are the best known. Evidence that permafrost is degrading in response to the current global warming trend is difficult to ascertain. The clearest signals are probably provided by changes in permafrost distribution in the sub-Arctic regions. at the extreme southern fringes of the discontinuous permafrost zone. [ABSTRACT FROM AUTHOR]