During paleogene times the deformation area associated to the Vallés fault system developed a series of compressive structures. In itially there was theem placement of a succession of thrusts and folds affecting mainly the mesozoic cover, whose erosion led to the deposition of mesozoic cover derived monogenic breccias and conglomerates. Subsequently the emergence of an out of sequence thrust, involving mainly paleozoic basement rocks was recorded in the basin by a paleozoic derived monogenic breccia level. Later on, basement and cover derived poligenic conglomerates and breccias were deposited as a response to the erosion of a more heterogeneous source area. The movement of a second thrust plate involving basement and cover rocks folded and thrusted the mesozoic cover and the tertiary deposits of the Ebro basin margin