Auswahl der wissenschaftlichen Literatur zum Thema „Periglacial phenomena“

In the medium-high mountains of Serbia (1,000-2,000 m.a.s.l), sporadic periglacial relief forms occur, which is also the case with Mount Vardenik (1,876 m.high), a mountain in the southeast of Serbia. During reconnaissance, certain relict and sub-recent periglacial phenomena and landforms in the highest part of the mountain have been identified: block slides, rock flows, thermogenic landslides in springs, nivation-induced relief and in one location cryoplanation terraces. Sparsely clustered and individual occurrences of frost splitting and solifluction of the land surface and small areas with grass turf indicate contemporary signs of sporadically present seasonal frost and freeze-thaw cycles. Periglacial morphology and its processes have been recorded and investigated using a qualitative geomorphological procedure. The main problem is the origin of periglacial phenomena (occurrences and landforms) of the relief, considering that the analysis of the contemporary climate, geoecological properties and anthropogenic activities indicate that there are no condi-tions for the existence and development of a contemporary periglacial environment on the mountain. The problem was analyzed considering the climate change in general and, in particular, geoecological conditions created under the influence of human activities. Due to the observed sporadic relict and sub-recent periglacial relief on Mount Vardenik, in contemporary conditions the periglacial environment of this area can be consid-ered as relict or as a phenomenon bordering the limits of differentiation. The relict property also results from the fact that on the mountain, due to the contemporary climate and changed geoecological conditions, the transition zone of the periglacial environment cannot be distinguished.

The writer proposes a simple and practical set of symbols for use in the preparation of periglacial maps. These maps can he constructed rapidly and at modest cost. In a preliminary section dealing with cartographie principles, the writer proposes that jour aspects of periglacial studies he mapped ; phenomena, « conditions », regions, and aspects of applied periglacial studies. Attention will also he given to chronology. Symbolisation conforms to the following scheme : drawings or designs for phenomena, lines and curves for conditions, line patterns for regions, and letters to indicate aspects of applied periglacial studies. Colours can he used where more than one cold period has occurred. The writer proposes in Table I (in pocket) the use of more than one hundred symbols for the representation, on a 1:50,000 base map, of periglacial phenomena. The problems of classification of periglacial phenomena are also discussed, with the writer suggesting a classification based upon group of process. Among the categories included are : gelisolation, gelifraction, gelifluction, nivalisation, action of floating ice, gelifluviation, wind action and polygonation. The text ends with a glossary of periglacial terms.

This paper presents the morphological and genetical characteristics of small forms of modern periglacial environment of the Balkan Peninsula mountains, called solifluctional scars. Except several previous observations, these forms have not been distinguished and considered as a type of a modern periglacial relief so far. Solifluctional scars are small phenomena of the horseshoe indentations in the pedological-vegetational base of the decimetermeter dimensions. They are formed by cleavage of the base by the use of a solifluctional sliding process with secondary processes of frost and linear water denudation during their subsequent evolution. As such, they can be seen as rudimentary phenomena of beginnings of linear flows of snowmelt, as well as a small mud solifluctionaltorrential flows, but also in general, as a segment of cryoplanation. These qualities classify them into a frame of rudimentary phenomena at the lower limit of the periglacial climazonal belt in the Balkan Peninsula mountains.

The author describes surface and undersurface landforms in the Čecher Hill (the Outer Western (Flysch) Carpathians) and outlines their origin and development. The main part of the article focuses on periglacial and pseudokarst (above all a pseudokarst cave in the Čecher Hill) landforms in this area. It also describes periglacial processes in the Pleistocene and the processes of humid character in the Holocene, which formed these landforms. The author takes notice of the relationship between landforms and geological conditions in the area.

Periglacial conditions which occur in Canada have been studied recently. Most of the research has been so jar limited in scope (mostly patterned ground and permafrost), undertaken for practical purposes (v.g. airport strips and the new Aklavik's site) and often carried by governmental agencies. Though a hundred titles or so of various articles and notes could be cited in a bibliographical survey of the topic, it must be underlined that the inventory of periglacial phenomena itself is still jar from being completed. This paper, prepared for the Canadian Committee of the International Commission of Periglacial Geomorphology, is based on a broad conception of the topic. The author suggests a useful series of new analytical concepts and outlines new fields for future research. The paper deals with three major aspects of periglacial studies : processes, datation and regions. Some of the processes and conditions are : terrain, wind, vegetation, the climatic « facies » (frozen ground, snow, air temperature and floating ice System). The author feels that all periglacial phenomena in Canada can be classified within a chronological sequence which he makes an attempt to establish as follows : a) Lower and Middle Wisconsin ; b) Pleniwisconsin ; c) Finiwiscon-sin ; d) Late Glacial ; and, e) Recent. Canada, in the opinion of Dr. Hamelin, can be divided into eleven periglacial « provinces ». The first jour provinces : Elizabeth, Victoria, Keewatin and Innuit are closely associated with continuous permafrost. Three provinces, Hudson, Labrador and Mackenzie, are situated in the periarctic zone. Two, Alberta and Saint-Laurent, have a southern situation along the parallel 50°N. Finally, two provinces : Yukon and Columbia, lie within the limits of Western Cordillera. These eleven provinces are proposed to serve for the designation of periglacial types or regimes throughout the cold regions of the world. The paper concludes with a glossary of new terms suggested for adoption.

The internal structure of periglacial landforms contains valuable information on past and present environmental conditions. To benefit from this archive, however, an enhanced understanding of subsurface variations is crucial. This enables to assess the influence of the internal structure on prevailing process regimes and to evaluate the sensitivity of different landform units to environmental changes. This thesis investigates structural variations in the subsurface of (i) rock glaciers,(ii) solifluction lobes, (iii) palsas/ lithalsas and (iv) patterned ground, which occur between the different landform types, but also between landform units of the same type. Investigated variables comprise (i) the spatial distribution of permafrost, (ii) ground ice content, (iii) the origin of ground ice, (iv) thickness of the active layer and (v) frost table topography. Multi-dimensional investigations by the geophysical methods Electrical Resistivity Imaging (ERI) and Ground-Penetrating Radar (GPR) were performed in six study areas (a–f): four of them are located in high-alpine environments in Switzerland and two of them are located in the subarctic highlands of Iceland. Additionally, surface and subsurface temperature values were continuously recorded at selected study sites. At one study site, pF-values, representing the matric potential (or water potential), were recorded. From a methodological view, this thesis focuses on the application of quasi-3-D ERI, an approach in which many two-dimensional data sets are combined to create one three-dimensional data set. This permits e.g., a three-dimensional delimitation of subsurface structures and a spatial investigation of the distribution of ground ice. Besides the analysis of field data, this thesis incudes a comparison between inversion models produced with different software products, based on two synthetic data sets. The detection of resistivity structures and reflection patterns provides valuable insights into the internal structure of the investigated landform units: At the high-alpine study site at (a) Piz Nair, a highly variable ice content indicates a complex development of the investigated rock glacier assembly. The local formation of ground ice is attributed to an embedding of surface patches of snow or ice into the subsurface by rockfall. Results of geoelectric monitoring surveys on selected rock glaciers show the influence of seasonal alterations in the internal structure on subsurface meltwater flow. At the study site at (b) Piz Üertsch, results indicate the occurrences of isolated ground ice patches in a significantly larger rock glacier. Detected characteristics of the internal structure enable to reconstruct the development of the rock glacier, in which a temporary override of an adjacent glacier tongue on the rock glacier is considered crucial for the current distribution of ground ice. However, results of this thesis clearly show the absence of buried glacier ice in the subsurface of the rock glacier. Results from a rock glacier near the (c) Las Trais Fluors mountain ridge affirm the existence of a water-permeable frozen layer, which was assumed in previous studies. Furthermore, results show that the rock glacier contains large amounts of rockfall deposits. A joint interpretation of ERI and GPR results from the investigated scree slope at the mountain (d) Blauberg (Furka Pass) reveals characteristic structures in the subsurface, which enable a differentiation between solifluction lobes and pebbly rock glaciers. At the subarctic study site (e) Orravatnsrústir, results show that the internal structure of palsas can be used to deduce their current development stage and to assess past and future developments. Presented results affirm a long history of palsa development at the study site, as assumed in previous studies, but indicate recently changing environmental conditions. The investigated occurrences of patterned ground in the proglacial area of the glacier (f) Hofsjökull are currently not influenced by the detected occurrence of permafrost, according to the presented results. Therefore, a temporary formation of pattered ground is assumed, which is linked to the retreat of the glacier. This thesis shows discrepancies between the internal structure of some of the investigated landform units and the recent environmental conditions. This indicates a delayed adaption and a low sensitivity of the landform units to environmental changes. Findings indicate that the future development of permafrost will be strongly affected by variations in snowfall. Furthermore, the detection of isolated occurrences of ground ice at several study sites contradicts the widely assumed effectivity of balancing heat fluxes to create homogenous subsurface conditions in relatively fine-grained subsurface materials
Der strukturelle Aufbau periglazialer Landformen beinhaltet wertvolle Informationen über vergangene und heutige Umweltbedingungen. Um diese Informationen nutzen zu können, muss jedoch ein vertieftes Verständnis für den Zustand der inneren Struktur und möglicher Variationen entwickelt werden. Dieses Wissen ermöglicht beispielsweise eine Abschätzung des Einflusses der inneren Struktur auf das momentan dominierende Prozess-Regime und eine Beurteilung der Sensitivität gegenüber sich verändernden Umweltbedingungen. Die vorliegende Arbeit untersucht Unterschiede im Aufbau von (i) Blockgletschern, (ii) Solifluktionsloben, (iii) Palsas/ Lithalsas und (iv) Frostmusterböden, die zwischen den Landformtypen, aber auch zwischen einzelnen Einheiten desselben Typs bestehen. Betrachtet werden dabei (i) die räumliche Verbreitung von Permafrost,(ii) der Eisgehalt im Untergrund, (iii) die Entstehung von Untergrundeis, (iv) die Mächtigkeit der Auftauschicht sowie (v) die Formung der Frosttafel. In sechs Untersuchungsgebieten (a–f), davon vier in Hochgebirgsregionen der Schweiz und zwei im subarktischen Hochland Islands, wurden Untersuchungen mittels mehr-dimensionaler geophysikalischer Verfahren, Widerstandsgeoelektrik (ERI) und Bodenradar (GPR), durchgeführt. Zudem wurden an ausgewählten Standorten kontinuierlich Temperaturwerte der Oberfläche und des Untergrunds aufgezeichnet. An einem Standort wurden ergänzend pF-Werte, die die Saugspannung des Porenwassers angeben, aufgezeichnet. Methodischer Schwerpunkt der vorliegenden Arbeit ist die Anwendung von quasi-3-D ERI, einem Ansatz bei dem Datenpunkte mehrerer zweidimensionaler Datensätze zu einem dreidimensionalen Datensatz vereinigt werden. Dies erlaubt beispielsweise eine dreidimensionale Abgrenzung von Untergrundstrukturen und damit eine räumliche Untersuchung der Verbreitung von Untergrundeis. Ergänzend zur Arbeit mit Felddaten enthält die vorliegende Arbeit einen Vergleich zwischen Inversionsmodellen, die auf Basis von zwei identischen, synthetischen Datensätzen mit unterschiedlichen Softwareprodukten generiert wurden. Durch die Detektion von Widerstandsstrukturen und Reflektionsmustern lassen sich wertvolle Erkenntnisse über den strukturellen Aufbau der untersuchten Einheiten gewinnen: Im hochalpinen Untersuchungsgebiet am (a) Piz Nair weisen stark schwankende Eisgehalte auf eine komplexe Entwicklungsgeschichte der untersuchten Blockgletschergruppe hin. Die lokale Entstehung von Untergrundeis wird auf Verschüttungen oberflächlicher Schnee- oder Eisfelder durch Steinschlag zurückgeführt. An einem Blockgletscher der Gruppe wird mittels geoelektrischer Wiederholungsmessungen der saisonale Einfluss der inneren Struktur auf den Schmelzwasserabfluss im Untergrund durch Veränderungen der Permafrosttafel gezeigt. An einem deutlich größeren Blockgletscher im Untersuchungsgebiet am (b) Piz Üertsch zeigen die Ergebnisse dieser Arbeit isolierte Vorkommen von Untergrundeis. Hier kann anhand der inneren Struktur die Entwicklung des Blockgletschers nachvollzogen werden, wobei insbesondere eine zeitweilige Überdeckung des Blockgletschers durch eine benachbarte Gletscherzunge als ausschlaggebend für die lokale Verteilung von Untergrundeis angesehen wird. Die Ergebnisse zeigen, dass kein Gletschereis in den Block gletscher eingebettet wurde. Die vorgestellten Ergebnisse der Untersuchungen an einem Blockgletscher nahe des Bergkamms (c) Las Trais Fluors bestätigen die dort in vorherigen Studien angenommene Wasserdurchlässigkeit der Frosttafel. Zudem zeigt der Aufbau des Blockgletschers das Auftreten großer Mengen von Steinschlagablagerungen. Am untersuchten Schutthang am (d) Blauberg (Furkapass) können durch eine gemeinsame Auswertung der Ergebnisse von ERI und GPR charakteristische Strukturen detektiert werden, durch die sich die dort auftretenden Lobenstrukturen in Solifluktionsloben und Feinmaterial-Blockgletscher (Pebbly Rock Glaciers) unterscheiden lassen. Im subarktischen Untersuchungsgebiet (e) Orravatnsrústir zeigen die Ergebnisse, dass vom strukturellen Aufbau von Palsas auf deren gegenwärtiges Entwicklungsstadium geschlossen werden kann und dass Rückschlüsse auf vergangene und zukünftige Entwicklungen möglich sind. Die vorgestellten Ergebnisse bestätigen die in vorherigen Studien getroffene Annahme einer lange zurückreichenden Entwicklungsgeschichte der Palsas, weisen aber auch auf sich seit kurzem verändernde Umweltbedingungen hin. Die untersuchten Frostmusterböden im Gletschervorfeld des (f) Hofsjökull zeigen gegenwärtig keine Beeinflussung durch Permafrost, obwohl ein rezentes Vorkommen von Permafrost angenommen wird. Daher wird eine temporäre Bildung der untersuchten Oberflächenstrukturen angenommen, die an den Rückzug des Gletschers gebunden ist. Die vorliegende Arbeit zeigt, dass die innere Struktur einiger der untersuchten Landform-Einheiten Diskrepanzen zu den momentanen Umweltbedingungen aufweist. Dies deutet auf eine geringe Sensitivität, beziehungsweise eine verzögerte Anpassung der Landschaftsformung auf sich verändernde Umweltbedingungen hin. Des Weiteren zeigt die vorliegende Arbeit, dass besonders Veränderungen im Schneedeckenauf- und abbau wesentlich zur zukünftigen Entwicklung von Permafrost in den untersuchten Gebieten beitragen werden. Die Beobachtung isolierter Vorkommen von Untergrundeis in mehreren Untersuchungsgebieten steht in Kontrast zur verbreiteten Annahme, dass die ausgleichende Wirkung von Wärmeströmen im Untergrund in feinkörnigem Material besonders stark ist
Periglacial environments are facing dramatic changes. Warming air temperatures and strong snow cover variations fundamentally affect landforming processes in this hotspot region of Climate Change. But before we can assess the response of landform development to a changing climate, we need to enhance our understanding of the internal structure of those landforms. Within this study, a broad scope of landform types from alpine and subarctic regions is investigated: rock glaciers, solifluction lobes, palsas and patterned ground. By using the geophysical methods 2-D and 3-D ERI, as well as GPR surveying, structural differences and similarities between landform units of different or the same landform types are highlighted. This enables a reconstruction of their past and a projection of their future development

This chapter is about what glaciers—and particularly what glacial and periglacial melt—mean to people and communities around the world. We often don’t realize that people interact daily with glaciers. Some go to visit and hike on glaciers or to photograph them for their magnificent beauty. Some ski on glaciers. Others extract water from glaciers for personal and industrial use. Others fear glaciers for their potent fury and destruction. People and communities are adapting to climate change and its impacts on glaciers, sometimes without even knowing it. Others are very aware of glacier vulnerability and are taking measures to address the changing cryosphere. They are mitigating circumstances and are adapting to impacts. In this chapter, we share stories and facts about glaciers and periglacial environments, which most people are probably unfamiliar with, and we explain how lives in these environments are changing due to climate change. Few people have heard of glacier tsunamis, but they exist, they’re real, they’re ferocious, and they can kill. Scientists call them glacier lake outburst floods (GLOFs). And as climate change deepens, more and more GLOF phenomena can be expected. Imagine you live at the foot of a mountain range like the Rocky Mountains, the Himalayas, or the Central Andes. On a nice sunny day, you can see the snow-capped mountains in the distance, maybe 20 or 30 km (12–18 mi) out, maybe even more. You are sitting at home when all of a sudden you feel shaking and hear a rumble. People start screaming. You look out the window and see people running frantically and erratically about. Then a woman yells, “The mountain! It’s coming! Run!” Imagine a large glacier the size of a dozen or so city blocks, perched atop a mountain. It’s 180 meters thick (600 ft), which is as tall as a sixty-story building. Below it, time and climate have formed a lake, a glacier lake occupying the same spot where the glacier once rested, pushing rock and earth out and forward as the glacier flowed downhill when it was solidly frozen and healthy.

There are two major recurrent themes in geomorphological research into granite landscapes. On the one hand, there is a recognition of the extraordinary diversity of landforms supported by granitic rocks, on a variety of scales, from microrelief on exposed rock surfaces to regional landscape types. On the other hand, there are striking geomorphic similarities between basement regions across the world, noted again at the scale of individual, almost omnipresent landforms, as well as in larger landform assemblages. To account for both diversity and similarity, various attempts have been made to produce a typology of granite landscapes. One of the early systematic approaches was that presented by Wilhelmy (1958) in his Klimamorphologie der Massengesteine. In line with the dominant paradigm in German geomorphology, he was an advocate of strong climatic control on the development of landforms and, accordingly, used climatic zonation of the globe as a basis for his classification system. Seven major morphoclimatic zones with allegedly distinctive phenomena of granite weathering and denudation have been distinguished. In addition, Wilhelmy emphasized climate-controlled change in landform inventories with altitude, citing examples from Corsica, the Sinai Peninsula, and Korea. Following Lautensach (1950), he specifically mentions mountain ranges in the Korean Peninsula, where a dissected landscape typified by deep ferruginous weathering gradually gives way to assemblages typical of harsh periglacial environments as altitude increases. The problem with the climatic approach is the likely co-existence of landforms and weathering patterns of different ages, hence formed in different environmental conditions, especially in middle and high latitudes. In fairness, it has to be said that inherited components have been recognized by Wilhelmy, but the evidence for inheritance is not always conclusive. Selected controversial examples have been presented in the previous chapters. These difficulties also raise a wider methodological issue, if climatic zonation of the globe is to be an appropriate framework to analyse granite landforms. Stoddart (1969) and more recently Twidale and Lageat (1994) offered insightful reviews in this respect, concluding that the uncertainties and limitations of climatic geomorphology are far too many to make it a preferred paradigm. Thomas (1974) adopted a different approach, a morphological one, attempting to identify characteristic granite landform systems.