Development of dissected flattening surfaces on coast range in the Maule Region, Central Chile

The fundaments of a geomorphological denomination for the coast range of Central Chile and the improvement of the corresponding theory are researched here. Three basic aspects were observed: presence of surfaces, deep weathering and tectonics. The modern theory of Rumpffäche was the central principle of analysis. It is deduced that the planation of the highest surface was favoured by

deep weathering, which is thought to have operated at least during the Miocene, supplying grus as principal material. The deep differential etching regulated valley incision. Starting from the principal valley, excavation of gigantic amphitheatres produced staircase surfaces, controlled by the weathering front. The presence of isolated homoclinal elevated surfaces and its incision by antecedent rivers, reveals post planation tectonic deformation. In order to denominate the coastal block,

it is proposed the use of the terms coast range, for the morphostructure and Rumpffäche or etchplain, for the morhosculpture.