The Betic Cordillera is a topographic manifestation of Miocene to recent collision between the African and the European plates. Mountain ranges in the Internal Zone of the Betic Cordillera are exhumed massifs of metamorphic and sedimentary rocks, and are surrounded by low-lying sedimentary basins. The Neogene history of mountain range uplift and basin formation in the Betics is well studied, but Quaternary topographic development and its relation to convergent plate boundary tectonics is less understood. Deformation, rates of stream incision and factors controlling landscape evolution on the flanks of the highest mountains in the Betic Cordillera are studied to gain insight on the relationship of Quaternary tectonics to topographic development. Specifically, geomorphic processes that led to formation of topographic relief within the Internal Zone of the Betic Cordillera are assessed. This paper is based on a field study conducted in the eastern Alpujarran Corridor (EAC), which is the eastern half of a 4–6-km wide and 80-km long inverted sedimentary basin. The Mid to Late Quaternary history of basin denudation is deduced on the basis of morphostratigraphic, geochronologic and structural–geologic analyses of oxygen isotope Stage 8-time fluvial deposits in the EAC. Results of these analyses indicate that climate and faulting played only a minor role in landscape evolution in the EAC. Instead, the EAC topographic trough was excavated by a drainage network whose axial stream (Río Andarax) was incising at a rate between 0.3 and 0.7 m/ka since oxygen isotope Stage 8. This paper demonstrates that these incision rates are the same as regional rock uplift rates in the EAC. During the Mid and Late Quaternary, topographic relief between the EAC and adjacent mountain ranges developed largely as a result of fluvial denudation driven by regional uplift. The implications of the results of this investigation are used to propose a model of Quaternary topographic relief development in the Internal Zone of Betic Cordillera. Topographic relief between Internal Zone bedrock massifs and adjacent basins formed largely as a result of fluvial denudation driven by regional uplift. Faulting also played a significant role in areas that are within a few kilometers of crustal-scale fault zones.

This paper benefited greatly from review and comments by F.J. Pazzaglia, M. Stokes, A.G. Sylvester and an anonymous reviewer. The first author would like to thank the following people for generous support and/or assistance while conducting field work: the Valdivia López family, Dr. Alice Alldredge and James M. King, Enrique Pérez Ibarra (a friend of the first author), Petra, Dr. A. Azor, Dr. R. El Hamdouni, Dr. C. Irigaray Fernández, Dr. K. Kleverlaan and, especially, Drs. A.E. Mather and M. Stokes. Enrique Pérez Ibarra located travertine sample T-12 and directed the first author to critical travertine sampling sites. This research was funded by the following organizations and grants: Vicerrectorado de investigación y relaciones internacionales, Facultad de Ciencias, University of Granada, Spain; Geological Society of America Research Grant; Sigma Xi Grant-in-aid of Research; University of California, Santa Barbara (UCSB) Academic Senate; UCSB Department of Geological Sciences “Block Grants.”

20 pages, 14 figures, 3 tables.

Peer reviewed