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This study focuses on a section of the Apulia Ionian-Sea coastline, between Torre Colimena and the town of Porto Cesareo, where pocket beaches of different size and shape are found. The larger pocket beaches comprise individual coastal systems which include coastal-plain, dune, beach and shoreface facies. Absence of sediment-delivering rivers, local production of bioclastic debris from a carbonate factory, and low volume and thickness littoral prisms are the main characteristics of these pocket systems. The coastal sediments are predominantly bioclastics ranging from coarse to fine, medium-fine, and very coarse sands on the foreshore, upper shoreface, and lower shoreface, respectively. The foreshore and upper shoreface sediments as well as the size of the backshore deposits vary according to the degree of coastal exposure to the seas, coming between west and southeast directions. Coastline urbanization and tourist activities have developed extensively during the last 40 years, and most of the erosional signatures have clear connections with nearby human disturbance. Dune degradation related to human activities together with aeolian processes, wave action and a low sediment production from carbonate-factory source are the factors responsible for beach and dune erosion during last years. Our topographic survey and sedimentological data indicate that most of the beaches have natural attributes conducive to flooding during marine storms. The substrate topography controls the size and shape of the study pocket beaches, the spatial arrangement of the coastal deposits and the hydraulic and sedimentary processes. Nearshore rip circulation occurs in most of these beaches.

Incised valleys and their fill represent important features of fluvial systems and can provide valuable information on external controls on sedimentation. Furthermore, the mode of stacking of multiple incised valleys may result in diverse connectivity of high permeability geobodies, which makes their origin and architecture important to understand for natural resources development. Based on dense borehole data and key outcrops along a 10 km-long transect, this study attempts at delineating the depositional architecture of a stacked multi-valley complex recording the Middle Pleistocene to Holocene evolution of the Tiber River system (Rome, Italy). Such a multi-valley complex is composed of four low rank/high frequency depositional sequences intercalated with pyroclastics, which fill in valley incisions entrenched into a substrate of Pliocene-Early Pleistocene marine clays. Owing to radiometric dating of pyroclastics, a robust correlation exists of valley incision and fill phases to odd and even Marine Isotopes Stages (MIS 14-1), which allows linking incised valley development to sea level changes. Located c. 20 km upstream from coeval shorelines, the investigated valleys have widths in the range of 0.5-2 Km and depth/thickness of up to 60 m and a recurrent tripartite pattern of their fills including: i) an up to 10 m thick and laterally extensive basal unit of dominantly gravelly-sandy deposits; ii) a middle unit (thickness in the range of 20-30 m) composed of vertically stacked sandy channel bodies (width in the range of 200-400 m) sided by floodplain muds; iii) a top unit composed of laterally stacked channel sands and, subordinately, floodplain muds, which result in extensive tabular sand bodies. Correlation to MIS suggests the fill of the studied incised valleys might reflect early deposition under low accommodation conditions within braided channel belts (lowstand and early transgressive phases) followed by deposition in sinuous channel belts (late transgressive and high-stand phases). In turn, successive incised valleys are stacked in an entrenching and westward shifting fashion, which is interpreted to reflect superimposition of regional uplift, topographic confinement from south-easterly sourced pyroclastics of the Albani Hills Volcanic District and glacio-eustasy. The resultant stratigraphic architecture of the Tiber multi-valley complex is such that high-permeability gravelly and sandy deposits are locally connected across successive valley fills. However, the studied example highlights how degree of connectivity of multiple incised valleys fills is ultimately controlled by external forcing factors (e.g. regional uplift and topographic confinement) superimposing to higher frequency changes of base level. It can be speculated that, by forcing lateral shifting of a fluvial stream, superimposition of differential uplift/subsidence to relative sea level changes more likely develops into less connected incised valley fills.

A review and correlation of borehole data, mostly from a recent survey of drilling in Rome (Palatino Hill and Fori Romani), and outcrops studies have allowed to reconstruct the stratigraphic architecture of the subsoil. Fluvial lithofacies of the ancient Tiber River system are recognized, which fill three high relief incised valleys of Middle Pleistocene age within of which well dated pyroclastites occur. These valleys constitute portions of the low rank/high frequency depositional sequences (PG4, PG5 and PG6) forming the Middle Pleistocene to Holocene composite/high rank Ponte Galeria Depositional Sequence (Milli et al., 2016). The latter represents the most recent stratigraphic unit of the Roman Basin. From a lithostratigraphic point of view the low rank sequences have a good correspondence with the Villa Glori, Fosso del Torrino and Quartaccio Synthems (Funiciello & Giordano, 2008) and are correlated to MIS 14-13, 12-11, 10-9 respectively. Valleys are elongated in N-S direction, and each of them has dimensions comparable to the tributaries valleys developing within the low rank Late Pleistocene-Holocene Tiber Depositional Sequence (Milli et al. in press): 1-2 km in width and up to 50 m in thickness. They are well entrenched into the substratum that is composed of Pliocene-Lower Pleistocene marine clay and Lower-Middle Pleistocene fluvial sediments and pyroclastites. The investigated valley segments are located some 20 km upstream from the coeval shorelines, nevertheless they show an internal stacking pattern of facies recording base level changes, in turn related to the Quaternary climatic and high frequency/amplitude sea level fluctuations. Each valley infill shows at the base a 10 m thick and laterally continuous body of amalgamated pebbles and sands forming a braided channel belt, deposited under low accommodation conditions and correlated with late lowstand and early transgressive phases. It follows a 20-30 m thick intermediate portion showing sandy-silty deposits attributed to sinuous channel belt, and laterally confined by muddy floodplain deposits, often rich in organic matter (transgressive phase). On the top, the channel sandy facies tend to widen and grade laterally to pedogenized floodplain mud. The three recognized incised valleys are organized into a compound-composite stack that records their progressive entrenchment and westward migration, in response to regional moderate uplift, to lateral supply from pyroclastic flows sourced by Colli Albani from SE, and to differential erodibility of the substratum.

An integrated approach to the study of the Central Apennines thrust system has been conducted, combining together new field, geophysical, organic matter maturity and mineralogical datasets. The area comprises one of the most studied basins of the Central Apennines: the Laga basin. It developed during the Messinian time and represents the link between the internal, uplifted, Lower Miocene fold-and-thrust belt to the west, and the external, more recent part of the chain, buried below a thick pile of synorogenic, Plio-Pleistocene clastic deposits of the Periadriatic basin to the east. The Laga basin is filled by several turbiditic sedimentary sequences, largely studied in the past and mostly included into the Laga Formation, classically considered the fill of a deep marine foredeep basin connected to the flexure of the subducted Adriatic lithosphere under the Apennines. Our results clearly suggest that during Messinian, the main factor controlling depositional system architectures was thrusts activity, which governed the localization of the main depocenter in the basin and its eastward space-time migration. The occurrence of thrust activity during deposition of most of the Laga basin sedimentary succession suggests that it can be described as an internally deformed but not migrating sedimentary wedge, having features recording the transition from foredeep to wedge top depozone.

It is widely accepted that deposition in lower reaches of river systems are primarily controlled by changes in relative sea level. Responses of fluvial systems to fluctuating s.l. are complex in terms of stratigraphic and depositional architectures, with resultant peculiar stacking patterns of facies and geometries of component elements, such as channel bodies and complexes, bars, and floodplain deposits. Changes in fluvial styles and facies are mainly studied in the frame of hydrocarbon exploration and aquifer characterization. Less studied are the relations between fluvial architecture and geotechnical setting of the subsoil for geohazards assessment. It is here presented a case study aimed at identifying and modelling highly compressible floodplain-related deposits, i.e. organic mud and peat layers, in the subsoil of Rome along the Tiber River alluvial plain. A large dataset of more than 2000 boreholes allows this fluvial system to be reconstructed in 3D, and to be directly correlated with laterally contiguous deltaic deposits, where lowstand, transgressive, and highstand systems tracts and related flooding surfaces are recognised. The lower reach of the Tiber system corresponds to a strongly laterally confined, upper Pleistocene-Holocene valley infill, up to 40 km long, 2 km wide, and 70 m deep, the base of which was carved in the substratum after the last glacio-eustatic sea level fall and lowstand (between 116 and 18 ka). The valley infill was developed in response to the postglacial sea level's rise and highstand (from 18 ka to Present). The fill is composed of three distinct lithofacies assemblages: 1) basal gravels and sands, up to 15 m thick, resting on the basal unconformity and interpreted as braided river sediments deposited in the early stage of TST; 2) silty sands and sands, that are arranged in vertically stacked channel-levee complexes (up to 200 m wide and up to 10 m thick), which increasingly widen in the intermediate-upper portion of the infill; 3) encasing floodplain muddy deposits, up to 40 m thick, and commonly rich in organic matter and peat. The assemblage 1 and 2, in particular, are referred to a meandering fluvial system and are correlated to TST and HST. Compressible organic mud and peat layers represents ancient palustrine environments and are concentrated in peculiar settings within the floodplain: 1) at the transition between fluvial and deltaic systems, in the TST; 2) close to the confluence of small tributaries with the main trunk, at the concave bank of the meanders, both in the TST and HST. In the first case the marshy deposits border the inner edge of a transgressive lagoon. In the second case organic rich deposits are interpreted to develop because of damming of tributaries from rapidly aggrading levees of the main river. In the city of Rome high levels of geohazard related to subsidence and differential settlements are located right at the confluences between tributaries and Tiber River, and are therefore referable to compaction of compressible deposits. These areas are highly urbanized and tributary streams are often channelled in sewer pipes and no longer observable. Unfortunately, the presence of the buried valleys is still testified by the differential settlements that affect buildings. An attempt to define a settlement susceptibility index was carried out based on the detailed stratigraphic-sedimentological reconstructions and on the large geotechnical dataset available for the alluvial deposits. Preliminary results are encouraging since they are in good agreement with field observations and deformation velocity maps from SAR interferometry

The possibility of inferring paleoflow conditions of the Messinian turbidites from the Laga Formation (Central Apennines, Italy) is here analyzed by solving an inverse problem. This inverse problem is solved for elucidating the condition for flow ignition for current velocity, height, and sediment concentration by comparing field data with an analytical solution for the change in bed elevation, related to net-depositional turbidity currents. The obtained layer-averaged values are 2-5 m/s for current velocities, 40-100 m for current thicknesses, and 0.1-2% for sediment volume concentrations. Moreover, the duration time of these flows has been also estimated. Results show values from 1 to 15 hours, depending on the energy of the turbidity currents. This variability in the hydrodynamic conditions also provides some insight into the high-order cyclicity observed into the Laga turbidite deposits. A brief discussion on the vertical structure of a net depositional turbidity current is finally presented. The hydrodynamic conditions of a three-layer turbidity current are inferred from classical tank experiments. The behavior of each layer during the net-depositional phase of a realistic turbidity current is consequently described by using layer-averaged results of the inverse problem, as a function of the Richardson number and the Reynolds number. Results confirm subcritical turbulent behavior of the thin basal layer, a middle layer with a reduced turbulence, and an upper layer with a turbulent cloud where the mean kinetic energy is smaller than the turbulent kinetic energy.

In the centrai Apennines, interacting siliciclastic and carbonate marine clastic wedges filled the foreland basin system during the late Miocene. Conjunction of collisional thrust tectonics and prethrusting norma) faults generated a complex foredeep with intrabasinal structural highs that represented additional source areas to the basin. Detrital modes of the late Miocene centrai Apennines orogenic system range in composition from intrabasinal carbonate to quartzofeldspatholithic and calclithite arenites. The external zone of the foredeep is characterized by hemipelagic deposits, called the Orbulina Mari. Their arenite beds are composed by intrabasinal carbonate, with dominant bioclasts and minor intraclasts, and glauconite derived from an active shallow-marine carbonate source. These hemipelagic deposits are partly coeval with an d partly overlain by siliciclastic turbidites of the Frosinone an d the ArgillosoArenacea Formations, and they represent deposition within local foredeep depocenters. Siliciclastic turbidite sandstones are quartzofeldspatholithic, which documents provenances from metamorphic, plutonic, ophiolitic, and sedimentary rocks. Carbonate intrabasinal structural highs were the main source for carbonate breccias, intrabasinal arenites, and calclithites ofthe Brecce della Renga Formation, the deposits of which are locally interbedded with the coeval siliciclastic turbidite sandstones. Evolution of late Miocene sandstone detrital modes reflected the changing nature of the centrai Apennines thrust belt through time an d the complex architecture of the foreland basin system; it records the history of accretion, deformation of the foredeep, and progressive areai reduction of carbonate-producing areas along with the sedimentary an d structural evolution of local intrabasinal highs.

This work investigates the physical stratigraphy and the sedimentological characters of the Messinian turbidites of the Laga Formation, central Apennines. In particular, the study concerns the lower Messinian portion of the Laga siliciclastic turbidites cropping out between the Mts. Sibillini and the Montagna dei Fiori-Montagnone anticline. The turbidite succession of the Laga basin was subdivided into three main allounits, Laga 1, Laga 2, and Laga 3, bounded by three unconformities and their correlative conformity surfaces, named I1, I2, and I3. Each of the three units show a fining and thinning-upward trend and they are stacked to form a succession with a clear forestepping pattern, reflecting the eastward migration of the basin depocentre induced by the Apennine thrust propagation. The sequence-stratigraphic interpretation of these deposits has allowed the three units to be framed in terms of 3rd- and 4th-order depositional sequences. Two 3rd-order sequences, namely Laga Depositional Sequence (LDS; uppermost upper Tortonian-lowerMessinian) and Cellino Depositional Sequence (CDS; upper Messinian- lower Pliocene), were recognized. The evolution of both the sequences was controlled by tectonic activity and climatic changes, and records an increased thrust activity followed by a slowdown of thrust motion and by a subsequent re-acceleration of the process. This work describes, in particular, the depositional and stratigraphic features of the LDS, which constitutes a thick turbidite complex where the main architectural elements of a fan can be recognized: from slope to basin floor passing through a channelized sector. Two main processes were considered as responsible for the generation of the turbidite flows: fluvial floods and submarine failures of variable volume. Both these processes were closely related to development of shelf margin deltas migrating basinward and landward, in connection to relative sea-level fluctuations forced by a variable combination of tectonics and climate changes.