Nebki - formy wymuszonej akumulacji eolicznej wschodniego obrzeżenia szottu Dżerid

• Autorzy: Dluzewski M. , Woronko B.

Warianty tytułu

EN

Nebkas - forms of forced aeolian accumulation of the eastern margin of the Chott Jerid

• Języki publikacji: PL

Abstrakty

EN

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.

• Wydawca: -
• Czasopismo: Prace i Studia Geograficzne
• Rocznik: 2006
• Tom: 37
• Opis fizyczny: s.69-79,rys.,tab.,wykr.,fot.,bibliogr.

Twórcy

autor

Dluzewski M.

• Zakład Geomorfologii, Wydział Geografii i Studiów Regionalnych, Uniwersytet Warszawski w Warszawie, Warszawa

autor

Woronko B.

• Zakład Geografii Stosowanej i Kartografii, Wydział Geografii, Uniwersystet im.Iwana Franka we Lwowie, Lwów

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