| Popis: |
In the coastal tract between Capo Mongerbino (Bagheria) and Piano Sperone (Altavilla Milicia), some forms (caves, terraces, erosional surfaces) of marine origin and of remarkable morpho-tectonic importance have been located. The caves lie at different altitudes ranging from about 200 m a. s. l. (Grotta Mazzamuto) to 7 m a. s. l. (Cala dell’Osta); the terraced areas, comprised between 0 and 200 m a. s. l., are arranged in five orders. In Sicily, the coexistence of both glacial-eustatic cycles and a slow uplift, caused by the Pleistocenic tectonics, resulted into the sea showing itself under different forms at different altitudes, presumably dating back to Middle Pleistocene. The age of each single event has not been always determinable owing to the general scarcity of faunal deposits and the impossibility to obtain radiometric data. Nevertheless, the complete definition of these events in a well-circumscribed time interval led us to make a first attempt at a space-time classification of the sea-origin forms and formulating the following hypotheses on the Pleistocenic morpho-tectonic evolution in this side of the Sicilian coast. 1. The Middle-Upper Pleistocene time interval includes all the events giving rise to both the marine terraces’ staircase and the caves; accordingly, tectonic events with a medium uplift rate of about 0,30 mm/a have been inferred. 2. A different morpho-tectonic evolution between the northern and southern areas of the Valloni de Spucches and Cefalà, cut along probable NE-SW fault lines and differential tectonic uplift, has been highlighted. 3. An intense post-Sicilian distension tectonic phase is here confirmed. |
