Génesis del modelado tipo mallo

In the Pyrenean External Sierras, a "pinnacle modelate" -Known as mallo in Aragón- very tipical of this transitional area is developed on conglomera te rocks. In the present work the factors that favour its development and evolution are analysed. The werstern portion of the prepyrenean Sierras is taken as a model for its study. Masive, well-cemented and very thick conglomerate rocks are needed for its genesis, which is favoured by the almost complete absence of stratification joints and the presence of regularly spaced perpendicular joints. Weathering and erosion -that model and individualize conglomerate blocks-, evacuation of material acumulated in the bottom, and in some cases gravitational movements of individualized blocks have to be considered in its development.