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The article includes description of nebkas - the smallest accumulation forms of aeolian origin. They originate from accumulation of wind-blown material accumulated on a lee side of a vegetation obstacle. The research was undertaken in the eastern part of the Chott Jerid, within its Holocene floor. Such forms are thought to indicate erosion of arid regions. Their appearance is usually linked to lowering of ground water table and related change in vegetation density. The researched was focused on two selected fields of nekbas. Morphometry and sedimentological features of building material were analysed. It was found that the shape of nebkas depends on a type of vegetation which constitutes the transport obstacles and forces accumulation. Lower forms (up to 0,5 m high) are created on a lee side of arfej species and are characterised by a high to length ratio 1:7 and so they have a typical shape of nebkas. Higher forms (up to 1 m) are created on a lee side of tamarix species and their high to length ratio is 1:4. Such a shape is due to a width of the plant and intensive erosion of a distal part of the form because wind frequently changes direction in this field. Sedimentological features of the forms show that material building the higher forms is better sorted comparing with lower forms and therefore it was probably transported for a longer distance. Mineral-lithological composition of the forms show a high share of quartz as well as relatively high share of gypsum (not resistant for abrasion). High content of gypsum in nebkas, seasonal capillarity with intensive evaporation lead to crusting of especially lower forms. Such a crusting strengthens the forms, protects from erosion of their distal parts and therefore explains differences in shapes of nebkas.
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Ewolucja i dynamika rzeźby okolic Pińczowa

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The major relief features of the Pińczów region (Ponidzie Pińczowskie) are the following: 1. Polygenetic nature of landforms, which are records of subsequent stages of the region’s geological development (both the youngest and the oldest landforms owe their contemporary shape not to one, but to many links in the evolution of the analysed relief). 2. Great importance of pre-Quaternary forms excavated from under younger deposits. ln this respect, Tertiary relief is the most significant. 3. Manifest dependence of morphology on tectonics and lithological differentiation of deposits (tectonics-based direction of relief, dependence of slope shapes from the substratum structure, occurrence of structural escarpments). 4. Presence and common occurrence of unique gypsum karst forms and their great diversity. 5. lnsignificance of glacial forms, whose remains can be found only locally, on hilltops of older elevations. 6. Considerable range of fluvoglacial cover. 7. Major significance of Holocene processes for the contemporary relief. 8. Important contemporary role of man in relief-forming processes, multitude and diversity of antropogenic forms. The graphic representation of relief (Fig. 2) manifests yet another important feature of the relief in the Pińczów region; it distinctly shows its division into horizons, relating to pre-Quaternary forms. Starting from the areas situated the highest, we can distinguish: • hilltop surface of the Pińczów Hummock at a level of approximately 260 metres a.s.l., with denudation mountains, partly covered with fluvioglacial sands, occasionally forming sand dunes. Culminations reach 270-290 metres above sea level. • Another level (230-250 metres a.s.l.) cuts through gypsum, limestone and marl of the Solec and Połaniec Basins. It is largely covered with denudated glacial forms and fluvioglacial sands. Above this level, gypsum and glacial relic mountains protrude. • In the western part of the Nida valley, the loess-covered spreads of the Wodzisław Hummock hilltop, occurring at the altitude of 280-330 metres, and lowering to approximately 250 metres on the slopes, correspond to the two surfaces described above. • At an altitude of approximately 230 metres starts the level of large, usually water-logged depressions, contemporarily used by rivers or intersected by a network of canals. Most probably, they are preQuaternary forms, possibly tectonic, transformed by glacial (and in some places karst) processes. • The remaining levels are distinctly related to the Nida valley and constitute its terraces -two Pleistocene and two Holocene, at altitudes ranging from 200 to 180 metres. The first three Ievels are autonomous in nature, with clearly marked slopes. The remaining levels are local erosion base levels and receive matter originating from the erosion of higher-situated areas.
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