Abstract
The High Basin of the Nalón River show fluvial valleys with a graded longitudinal profile under 750-650 m and deposits resulting from three terrace levels (T1, 30 m; T2, 10 m; T3, 3-4 m) and the present aluvial plain. The fluvial network, with a 6th order, fits to the theoretical Horton principles; there is not a correspondance between the relief parameters and the hypsometric integral value (39%), due to methodological restrictions; the geometrical parameters suggest a quick rainfall response; the low value of the drainage density (2.62 km/km2) is according to the physical basin features. The fluvial morphology is conditioned by the lithological variety of the Palaeozoic bedrock; by the Hercynian and Alpine Tectonics influence and by the Quaternary evolution of the area, which still shows a lackness of regional data.
