Alfred Jahn

Articles

Slow soil movement as a global phenomenon

Alfred Jahn

Geographia Polonica (1992) vol. 60, pp. 5-24 | Full text

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Abstract:

Slow mass movement of the soil is a form of transporting of slope material. It can be classified according to: the dynamics of the process, the structure of the movement (particles, layers) and the relation to the morphological surface (shallow or deep movement). In this way it is possible to distinguish soil creep as the important process within this group of mass wasting factors. Seasonal creep is first of all a function of climate whereas continuous or rheological creep is a function of geological structure.The slow movement of the soil depends on local factors (slope angle, moisture of the soil, vegetation cover) and on latitudinal and altitudinal climatic zonal factors (temperature, precipitation). The rate of soil movement in the polar (periglacial) zone is the highest on the globe. It is, as mass movement of the soil, three times higher than in the alpine zone. The soil creep processes in temperate climates are relatively small but greater than in the tropic zone. The smallest soil movement is in the arid and semi-arid zone.

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Alfred Jahn, Geographical Institute, University of Wrocław, Wrocław Poland

Periglacial structures in Svalbard as indicators of a Central European climate in the last glaciation

Alfred Jahn

Geographia Polonica (1992) vol. 60, pp. 79-101 | Full text

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Abstract:

Contrary to widely held opinions, the archipelago of the Svalbard Islands does not belong to the oceanic part of the periglacial zone but has its own diversified climate being humid-maritime on the coast and dry-continental in the interior. These differences in the periglacial enviroments manifest themselves in contrasting structures of the active layer. The periglacial zone of the last glaciation in Europe was characterized by a climatic gradient more oceanic in the west and more continental in the east of Europe. The transitional section of this zone lay in its narrowest part, between the Scandinavian ice border and the northern timber line, delimited approximately by the arch of the Alps and Carpathian Mountains. In this part periglacial structures are abundant and, what is more variable in vertical profile.This evidence reflects great variations in the glaciation period, of changes of the oceanic and continental phases. There are at least 4 frost wedge horizons, often of "sand wedge" type, that are indicators of a continental climate. The Svalbard archipelago where oceanic as well as continental facies of periglacial structures can be found at present provides a good representation of the spatial diversity of periglacial phenomena which occurred at different times in Central Europe.

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Alfred Jahn, Geographical Institute, University of Wrocław, Wrocław Poland

Main features of the Tertiary relief of the Sudetes Mountains

Alfred Jahn

Geographia Polonica (1980) vol. 43, pp. 5-24 | Full text

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Alfred Jahn, Geographical Institute, University of Wrocław, Wrocław Poland

Niveo-eolian processes in the Sudetes Mountains

Alfred Jahn

Geographia Polonica (1972) vol. 23, pp. 93-110 | Full text

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Alfred Jahn, Geographical Institute, University of Wrocław, Wrocław Poland

Morphological slope evolution by linear and surface degradation

Alfred Jahn

Geographia Polonica (1968) vol. 14, pp. 9-22 | Full text

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Alfred Jahn, Geographical Institute, University of Wrocław, Wrocław Poland

Denudational balance of slopes

Alfred Jahn

Geographia Polonica (1968) vol. 13, pp. 9-30 | Full text

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Abstract:

Twelve years ago in the Polish geographical journal "CzasopismoGteograficzne" (Vol. XXV, 1954) was published a paper by A. Jahn underthie same title as the present one. Although published in Polish, the paperstimulated great interest among geomorphologists from different countries,who learned its content from the short French summary. The sumnuarygave no comprehensive idea of the author's thesis, and not allreeaders adequately understood from it the problem of the "denudationalbailance of slopes" — as we know from the author. Therefore it wassuiggested that the paper be reprinted in English, and this is being donewiith the approval of the author.

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Alfred Jahn, Geographical Institute, University of Wrocław, Wrocław Poland