GEOMORPHOLOGY OF SANTA ROSA DE OSOS (ASRO) HIGHLANDS.

Abstract

The highland of Santa Rosa de Osos (ASRO) is a tectonically uplifted erosion surface (etchplain) also known as altiplano. It occupies the axis of the northern part of the cordillera Central of the colombian Andes and defines with other adjacent similar units a stepped structure of altiplanos in this sector of the mountain range. This bigger structure gives to the northern sector of the cordillera a truncated pyramid form, this form contrasts with those that the cordillera presents in the contiguous tracts located in the departmento de Caldas.

The ASRO is a homoclinal tectonic structure dipping toward the south, this is evident in the systematic distribution of altitudes; homoclinal structure is relatively old (pre-quaternary) and it could be associated, hypothetically, with the collision with islands arch of “Panama-Baudó”. Into the altiplano is persistent the presence of a stepped structure of natural and extensional very diverse geomorphic units; this structure is repeated in geomorphic units inscribed in the scale of 103 km2 until those inscribed in the scale of 10-1 km2 and it is expression of the importance of the past and recent tectonic risings. These movements impose structural conditions for the unfolding of the trajectories of relief evolution. The geomorphic diversity at ASRO expresses the existence of geomorphologic evidence that includes the entire Quaternary and a considerable part of the Tertiary. The truncated morphology of the axis of the mountain range is possibly an evidence of the early phases of its rising.

Keywords: Etchplains; stepped etchplains; denudativa planar surface; inselberg range; geomorphometry; Santa Rosa de Osos; Cordillera Central; colombian Andes.