| Abstract: | The Gaudix Basin developed as an endorheic depression during the Upper Miocene-Upper Pleistocene. Its principal palaeogeographical lcharacteristics are a large lake in the eastern sector, an axial fluvial system and two fluvial systems transverse to it in the western sector. The uplift of a central sector of the Betic Cordillera during the Upper Pleistocene affected the study area, causing northward tilting from the Internal Zone of the cordillera (Sierra Nevada and Sierra de Baza), step-faulting of the Plio-Pleistocene infill of the ancient basin (leaving more northern sectors in a lower topographical position), alteration of fluvial current profiles and displacement of the ancient Axial System to a position very close to the divide between the ancient endorheic Gaudix Basin and the Guadalquivir Basin. This facilitated capture of the endorheic basin by the headward erosion of a tributary of the Guadalquivir River. The region then began to be rapidly eroded, as the new base level was now some 500 m lower than that of the ancient basin. The present drainage network is similar to that of the ancient endorheic basin as regards the location of the main streams and the distribution of drainage patterns and fluvial styles, although flow reversal is found in some stretches and a barbed drainage pattern appears locally. As a result of the inheritance of drainage from the ancient basin, fluvial superimposition is found in some stretches of the main streams. © 1997 by John Wiley & Sons, Ltd. |
