Planation surf aces at the Republic of Guinea-Bissau territory

Abstract

Planation surf aces are well pronounced in the topography of the Republic of Guinea-Bissau. They came into being during the Late Alpine macrocycle of the relief formation. Two planated surfaces belong to the African stage (Late Cretaceous - Oligocene) 'and are designated as Early and Late African respectively. Since Miocene a post-African pediplain formation begins which marks the epoch of global pediplanation. The process proceeded along with erosion and alluviation in river valleys. Early African surface remnants persist only in the South-East of the country. The Late African surface is widespread in eastern regions. Post-African pediplain can be found practically all over the country. Eriosional-alluvial surface distribution is mostly controlled by long-existed faultlines of NE and NW directions. Each surface is fixed by a special type of hypergenous autochthonous or allothigenic formations; the latter's structure and composition having been determined by the climate at the time of their formation.