We examine the tectonic geomorphology of La Sila, Calabria, southern
Italy, a high-standing (1500 m) plateau surrounded by crustal extension, with map,
DEM, and field data. These data are used to constrain a simple geodynamic model that
describes short-wavelength deformation of the plateau rim. Topographic metrics
including drainage patterns, river longitudinal profiles, and swath profiles are consistent
with field stratigraphic relationships collectively suggesting that local tectonic
deformation is embedded within a broader, regional uplift that has increased the mean
elevation of the Sila Plateau during the Quaternary. The concavity, steepness, and
length-gradient index of modeled river longitudinal profiles proved to be the most
useful metrics for recording the effects of locally active faults. A previously unrecognized
horst on the northeastern portion of the plateau was identified with these data.
Nevertheless, the core of the Sila Plateau remains relatively undeformed with respect
to its flanks which are characterized by steep, fault-bounded escarpments. Active
extension has dropped base level for and unloaded the plateau rim, causing deep
fluvial incision and associated flexural uplift of the footwall. This footwall uplift helps
maintain a separate external, and nearly radial drainage away from the plateau along its
flanks, and a nearly closed drainage for the plateau interior. A drainage divide roughly
correlates with the plateau rim, inhibiting the process of drainage integration through
the Sila interior and subsequent landscape dissection. As a result, geomorphic processes
driving erosion of the Sila upland are lagging behind the tectonic processes that
have driven rock uplift leading to an overall increase in mean surface elevation. These
results underscore the importance of the lag times a landscape may endure in
transforming from one tectonic and base level condition to another. We conclude that
the Calabrian forearc has a similar geomorphic evolution as the more northern
Apennines consistent with the emerging view that growth of Apennine topography has
been recent (Quaternary), rapid, and possibly decoupled from rock deformation in
the orogenic wedge