Some observations on the geomorphology in the municipality of Urrao, Antioquia - Colombia
DOI:
https://doi.org/10.32685/0120-1425/bolgeol25.2.1982.355Keywords:
Alluvial plain, deposits, gravels, Penderisco river, embedded terraces, Frontino
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Copyright (c) 1982 Servicio Geológico Colombiano
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Abstract
Part of the municipality of Urrao is located on a wide alluvial plain with modern gravel deposits dissected by the Penderisco River and some of its tributaries, giving rise to terraces that occupy low topographic levels. At higher topographic levels, stepped plains extend from the Penderisco river valley to the foot of the Frontino Paramo Stock, whose general profile can be divided into four parts: escarpment, slope, concave slope, and straight slope, possibly originated by combined tectonic and climatic effects. These plains are formed by a heterogeneous mixture of blocks of igneous, sedimentary, and rare volcanic rocks, all of them coming from the Páramo. Some blocks are found occupying isolated hills, far from their source of origin. This may be related to the original erosion surface and the new hydraulic regime evidenced by the current course of the Penderisco River. Both the slopes of the hills above the Penderisco valley and those on plains at higher topographic levels are low angle, which does not necessarily reflect an age for the geoforms. In some cases, fluvial erosion seems to significantly affect the deeping of the valleys’ profile. Therefore, only near the Páramo are the slopes steep, and the valleys have a closed V-shape.
The rocks that outcrop in the area are sedimentary rocks of the Penderisco Formation, of late Cretaceous - early Tertiary age, which was intruded by the Páramo de Frontino Stock of late Tertiary age. In general, the geomorphological development of the area is related not only to weathering and erosion processes but also to the physicochemical characteristics of these rocks.
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