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.

Rock uplift rates can be diffi cult to measure over 103–105 yr time scales. If, however, a landscape approaches steady state, where hillslope\ud erosion and rock uplift rates are steady and locally similar, then it should be possible to quantify rock uplift rates from hillslope erosion rates.\ud Here, we test this prediction by comparing channel steepness index values and 10Be catchment-averaged erosion rates to well-constrained\ud rock uplift rates in two landscapes in Italy. The fi rst fi eld area is the Romagna Apennines, northern Italy, where rock uplift rates are relatively\ud uniform, between 0.2 and 0.5 mm/yr (regional mean 0.40 ± 0.15 [SE] mm/yr), and have been steady since 0.9 Ma. The second area is the\ud region around northeastern Sicily and the southernmost Italian peninsula, where rock uplift rates are higher and exhibit a strong spatial\ud gradient, from ~0.7 to ~1.6 mm/yr (regional mean 1.09 ± 0.13 [SE] mm/yr). In both regions, channel steepness indices and 10Be erosion rates\ud vary directly with rock uplift rates. Although there is considerable variability in erosion rates, regionally averaged rates in both the northern\ud (0.46 ± 0.04 [SE] mm/yr) and southern (1.21 ± 0.24 [SE] mm/yr) areas accurately measure rock uplift rates. Although channel steepness indices\ud do not quantify rock uplift rates, they are useful for (1) identifying regional patterns of rock uplift, (2) identifying areas where uplift rates\ud might be expected to be uniform, and (3) informing 10Be sampling strategies. This study demonstrates that, together, channel steepness and\ud hillslope erosion rates can provide a powerful tool for determining rock uplift rates