Landscapes and landforms connected with anthropogenic processes over three millennia. The Servian Walls at the Esquiline Hill (Rome, Italy)

Urban centers are characterized by scarcity of outcrops. At the urban-planning level, the examination of results from previous geological surveys and studies may provide sufficient data for an accurate subsurficial geologic modeling. In addition, in historical centers a GIS-based multitemporal analysis of historical and archaeological maps, and the examination of archive documents and reports, may be effective especially for the detection of geomorphic changes. The application of such a methodology at the Esquiline Hill allowed to detect the three-millennia-long landscape-modification main phases connected with the construction of the oldest city walls. They include a unique sequence of anthropogenic aggradational and erosional phases that shaped many anthropogenic landforms, presently visible and invisible, or vanished. Among them, the anthropogenic hill Monte della Giustizia, vanished since the end of the 19th century CE when it was erased, and the military moat, excavated in the 6th century BCE and enlarged in the 4th century BCE, finally backfilled in the 4th century CE, since then invisible. These geomorphic changes lastly output a flat leveled landscape similar to the previous volcanic plateau. Results suggest that the “geomorphological convergence,” that is, the resemblance between natural landforms created by different morphogenetic processes, also exists between natural and artificial landforms. Moreover, the study evidenced relationships between landforms and the damage status of historical masonry buildings, specifically connected with their foundation over thick layers of geotechnically-weak anthropogenic deposits. This advises that the multidisciplinary approach may also provide risk managers additional geological features to be evaluated as potential sources of natural hazard.