The possible relation ship between the Tejoneras and the Ciudad Rodrigo stratigraphic units of the terciary secuence filling the western part of the Ciudad Rodrigo basin is analyced in this paper. A tectonic model is also established. According to it, the southern border of the basin is limited by a single fault, striking NNE, which has been broken and reajusted by later faults followins NNW to NW direction. During the Oligocene and Early Miocene the Arcosas de la Alamedilla Formation was deposited on the southern egde of the Ciudad Rodrigo trough. This unit is the result of a dismanteling of a granitoid source areas present day situated to the S, SW and N by large ephemeral low sinuosity fluvial systems.
Pollen analysis suggests the existencc of a temperate climate with a seasonal nature.
On considering the evolution of the floristic associatgions through the stratigraphic section stratigraphic a gradual replacement of the tree taxa by those of herbaceous species may be observed. Joint palynological, stratigraphic and sedimentological studies show that during the sedimentation of the Arcosas de La Alamedilla Formation the landscape was opened, covered by braided fluvial systems of proximal sands and governed by a seasonal temperature climate. Ciudad Rodrigo Sanstone Formation. This Unit consist of clastic sediments derived from the weathered metamorphic and plutonic rocks placed in NW, SW and S of the basin. Paleocurrent measurement reveal a convergent pattern which coupled with the existent paleo-reliefs towards the NE, suggest and endorheic basin that was progresvely filled up by alluvials fans sediments.