GEOMORPHOLOGY

   The more recent changes in Etruria are relatively under-studied. However, there have been investigations of the delta region of the Arno near Pisa, of the lagoons near Populonia, and of some of rivers in the Faliscan area in relationship to archaeological evidence. The constraints of the geology have led to pronounced alternation of aggradation and erosion, leading to a cut-andfill stratigraphy that has both a general pattern (perhaps a result of climatic change) and local variations (perhaps a result of human land use). Studies of erosion and sedimentation in South Etruria have shown dramatic changes to the local environment. Initially these were interpreted as a product of climatic change. More recent studies have demonstrated quite clearly at least a contribution of human impact. More specifically, Roman activity contributed greatly to these human-induced changes but some of these changes may have started locally in Etruscan times. Roman rivers and floodplains were very different from those of today. They were distinguished by a regime of shallow, actively migrating channels that were depositing bars of gravel. These conditions may in turn have necessitated some of the Etruscan and Roman engineering schemes to control and traverse the changing environment.

   Within the peninsula, alluvial plains are more numerous on the Tyrrhenian coast, but are usually hemmed in by hills and mountains. The most prominent example is the Maremma. Most plains are simple strips, bordered by a beach of about 20 to 25 meters above sea level. The Tyrrhenian coast is generally characterized by alternating headlands, smaller or larger embayments, and prominent lagoonal formations. To the north and the south, the coastline is more rocky, with less obvious geomorphological action.