Morfo-litostratigrafia dell'area romana in sinistra Tevere

Abstract

This paper deals with the basic concepts of a procedure which relies on the very close integration of morphologic and strati-graphic features, with the goal of emphasising the potential of this procedure in reconstructing the Quaternary geologic evolution of a region. Two morpho-lithostratigraphic sequences have been identified and studied in detail, one in the Pomezia area (on the coast south of Rome) and the other in the Monterotondo area (NE of Rome). Each sequence spans the entire Quaternary. Although the sequences are distant from one another and developed in different interconnected environments (marine, littoral, fluvial and volcanic), the deposits can be reasonably well correlated (due to the presence of various markers) and remnant surfaces are in good accordance. From the point of view of neotectonics, the identified step morphology clearly confirms that the area around Rome has undergone more or less continues uplift since the Early Pleistocene. Moreover, the grade of the inferred top surfaces of the lower terraces is essentially parallel to the grade of the present valley bottom, suggesting that significant vertical displacement has not occurred between the two zones since the Middle Pleistocene. From the point of view of stratigraphy, a synopsis of previous studies has highlighted some uncertainties in the literature. By comparing this review with the results of this study one can observe further inconsistencies. An important consequence is the deduction that the presently accepted succession of erosional periods may have been based on the misinterpretation of limited erosional features as being due to general marine retreats. The procedure discussed is thus proposed to re-evaluate this succession on the basis of a large-scale reconstruction of the geologic evolution.