The Authors describe a sequence some 4 metres thick composed of slope and loess deposits which lies at an altitude of 360 metres, 20 metres above the Torrente Agna. The series belongs to a polyciclic soil composed of 4 lithostratigraphic units which, from the bottom to the top, are as follows: - slightly weathered loess (IV CI); - red clayey soil sediments (Ill B2) resulting from the erosion of a more ancient paleosol of «Terra Rossa» type, developed during the Middle Pleistocene at the top of the Carvanno Tarvertine; - undisturbed loess and loess displaced by gelifluction (II B21till B231); - recent colluvial deposits (A I + B1). The sequence was deposited between the Upper Pleistocene and the Holocene. During the Upper Pleistocene the loess deposition, alternated with colluvial and gelifluction phases, was caused by cold-humid climatic conditions. During the postglacial, the loess was affected by weathering which lead to the development of an alfisol. The micromorphological analysis evidenced several stages in the postglacial soil forming process. First, in unstable geomorphological conditions, complex cutans (scheletans-matransiltans) covered the walls of the soil pores. In a later period, as a result of landscape stability, laminated and birefringent [erri-argillans were mainly deposited. The deposition of the upper colluvial cover (AI + BI) and the coarse fills of the underlying horizons were produced by a degradational phase due to the deforestation of the area in historical times. The undisturbed argillans of the AI + BI horizons indicate that the clay illuviation is still active in the area.

Depositi eolici e di versante al margine dei travertini di Carvanno (Val Degagna, Brescia): sedimentazione e pedogenesi tra il Pleistocene superiore e l’Olocene. Loess and slope deposits at the edge of the Carvanno Travertine (Val Degagna - Brescia). Sedimentary processes and soil development between the Upper Pleistocene and the Holocene.

BARONI, CARLO;
1987

Abstract

The Authors describe a sequence some 4 metres thick composed of slope and loess deposits which lies at an altitude of 360 metres, 20 metres above the Torrente Agna. The series belongs to a polyciclic soil composed of 4 lithostratigraphic units which, from the bottom to the top, are as follows: - slightly weathered loess (IV CI); - red clayey soil sediments (Ill B2) resulting from the erosion of a more ancient paleosol of «Terra Rossa» type, developed during the Middle Pleistocene at the top of the Carvanno Tarvertine; - undisturbed loess and loess displaced by gelifluction (II B21till B231); - recent colluvial deposits (A I + B1). The sequence was deposited between the Upper Pleistocene and the Holocene. During the Upper Pleistocene the loess deposition, alternated with colluvial and gelifluction phases, was caused by cold-humid climatic conditions. During the postglacial, the loess was affected by weathering which lead to the development of an alfisol. The micromorphological analysis evidenced several stages in the postglacial soil forming process. First, in unstable geomorphological conditions, complex cutans (scheletans-matransiltans) covered the walls of the soil pores. In a later period, as a result of landscape stability, laminated and birefringent [erri-argillans were mainly deposited. The deposition of the upper colluvial cover (AI + BI) and the coarse fills of the underlying horizons were produced by a degradational phase due to the deforestation of the area in historical times. The undisturbed argillans of the AI + BI horizons indicate that the clay illuviation is still active in the area.
Baroni, Carlo; Cremaschi, M.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11568/8042
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