Pereira D. e Azevêdo T.

Monografias 2, La Rana en Espana y Portugal, 1993, Centro de Ciencias Medioambientales. Madrid.

Resumo
Red essentially conglomeratic deposits are disposed over a substract with various lithological characteristics - ultramafic and mafic rocks of the Bragança Complex (Precambric) and schist and quartzitic paleozoic facies that, along with some limited granitic outcrops, constitute the deposits' sources. The reactivation of hercynic faults during the Cenozoic and Quaternary are in the origin of the landscape's contrast between the Montezinho and Nogueira mountains and the elongated NNE-SSW basin, that extends itself from the spanish frontier to the south of Bragança and where these sediments were deposited. With a propicious climate the necessary geomorphological conditions were created for the deposits' formation. The mapping, cross sections and sedimentological analysis constitute a basis of strong support for the definition of the environmental evolution. The sedimentary bodies' shape and the analytical data obtained from the study of the pebble, gravel, sand and clay minerals allow to define the sources and genesis conditions of these deposits with alluvial fan characteristics. Globally these materials present all the aspects that allow to identify them as Iberian Ranas although, as has been referred by spanish authors (SERRANO-GARCIA,1988), these also aren't flat-lying bodies at the top of tablelands.