Evolucion de la costa atlántica onubense (so España) desde el máximo flandriense a la actualidad

The maximum Holocene Transgression, dated as around 6,900 years BP, gave rise initially, in this area of the Iberian south Atlantic coast, to an irregular coastline with wide inlets (estuaries) and prominent continental capes. These estuarine areas would become the lower stretches of the main fluvial systems (Guadiana, Piedras, Tinto-Odiel and Guadalquivir). The relative stability of the sea level (which continues today) has aided the straightening out of the coastline, with retreat of the continental promontories and the formation of cliffs. Littoral accumulative landforms have developed in the estuarine areas, prograding in the direction of the prevailing drift current (eastwards). Since the Guadalquivir mouth shows the most extensive and best conserved sedimentary formations, we can establish there with the greatest chronological accuracy the different Holocene cycles of progradation and retrogradation, with geomorphological corroboration from the other estuaries. Thanks basically to geomorphological mapping, 14C dating, and archaeological evidences, a series of prograding phases can be established for this coastal area. The first of these must have taken place 6,900-4,500 years BP, although there are not yet reliable data. The second phase was between 4,200 and 2,600 years BP, the third between 2,300 and 1,100 years BP, and the fourth - and last - between 1,000 and the present. There were separations of successive erosional phases between 4,500-4,200 years BP, 2,600-2,300 years BP, and 1,100-1,000 years BP. A progradation rate of 2-4 m/yr for the last 1,800 years has been established for the littoral spit of Donan̄a. In the prograding phases, sea level was stable or decreased slightly, with domination of the fluvial medium and greater filling with sediments, so restricting estuarine geometry. During the retrograding phases, sea level increased slightly, implying marine domination in the estuary, and greater erosive activity on the cliffs.

Bibliographic Details

Main Authors:	Rodríguez Ramírez, Antonio, Rodríguez Vidal, Joaquín, Cáceres Puro, L., Clemente Salas, Luis, Cantano Martín, M., Belluomini, G., Manfra, L., Impronta, S.
Format:	artículo biblioteca
Language:	Spanish / Castilian
Published:	CSIC - Instituto Geológico y Minero de España (IGME) 1997
Online Access:	http://hdl.handle.net/10261/58434
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