Results of micropaleontological studies of numerous sections from many localities and different ages in Egypt suggest that tectonics control the appearance and areal distribution of species. The movements that affected the stable shelf are epeirogenic, originating wide-scale transgressions and regressions that cause rock facies and associated biological assemblages to shift gradually in the direction of the new shore. Epeirogenic domes of this belt are big structures that produce diastems or at most unconformities without visible angular discordances. The distribution of rock facies as well as faunas around these structures is uniform and rock lines are almost time-parallel. Several basins of this belt are recorded but the best known of these is that of the Gulf of Suez g aben which shows a pattern of distribution of foraminiferal species that seems to be directly connected with the degree of tectonic activity exhibited by different parts within this basin.

The mobile belt was most probably overlapped by seas throughout most of its geologic history. The distribution of rock facies and their biological assemblages is not, therefore, connected with transgressions or regressions but rather with the relative position of the locality to the numerous highs that traversed this belt throughout its history. Structures are small, of compressional origin, and with varying degrees of activity on their sides. They have their inception at different ages. This produces complex patterns of areal and vertical distribution of foraminifera.