The Pleistocene sedimentary succession around the north Hyblean Mountain margin is dominated by three carbonate units, which are the subjects of this study. These "temperate" bioclastic carbonates developed around the shelf margin of a graben-generated embayment (Lentini Graben) and volcanic sea-mount topography facing the Catania Plain. Although showing considerable thickness variations within the study area all units are part of a widespread regional development. The lowest unit (principally Santernian) is primarily developed between Scordia and the Catania Plain. The middle unit (Emilian) is most widespread and extends at least from the Caltagirone area in the west to the Agnone area in the east. Finally, the youngest lithified carbonate unit (Middle Pleistocene in age) is developed throughout the NE region from Scordia to Villasmundo. In deeper marginal areas the carbonates pass into detrital, deep water pelagic marls which appear to have been deposited continuously throughout the early Pleistocene. The region was selected for study because of the high rate of post-depositional uplift which have raised the sediments into upland areas, now readily accessible along deep valleys. Cases are presented to demonstrate that: a) the carbonate units have significant regional distributions; b) each unit is tightly constrained in time; c) the overriding sedimentological controls on carbonate production were climatic, with primary carbonate production being confined to warmer, highstand parts of glacially controlled eustatic cycles. Bioclastic carbonates of similar ages have widespread developments throughout, other regions of the Mediterranean. This is the first attempt to accurately document their sedimentological characteristics and tie down their distributions in space and time within a well exposed region. The climatically driven eustatic component controls the timing of carbonate production and makes these successions critical to the correlation of marine and terrestrial Quaternary faunas throughout the Mediterranean. For these reasons each unit is precisely characterized to enable clear comparison with strata beyond the region.