The core of granite and Cordillera is, to a large extent, flanked by sedimentary layers from the Cretaceous, folded in an anticline structure. Between these orographic systems there are plains covered with tertiary and quaternary layers of gravels, sands and clayey marls. The depression in which are lagoons and lakes, among which is that of Maracaibo, presents, on the surface, alluvial deposits from the Quaternary, on layers of the Cretaceous and Tertiary particularly important, because of them oil infiltrations emerge.