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Notes: Detailed three-dimensional (3-D) observations of sandy point-bar deposits from the River South Esk in Scotland were made using very closely spaced (metres) vibracores and ground-penetrating radar (GPR) profiles. In order to explain the origin of the observed patterns of deposition, use was made of previous studies of channel geometry, flow and sediment transport. In addition, the mode and nature of channel migration and point-bar accretion were determined using published maps, aerial photographs and detailed topographic surveys. Point-bar deposits accumulated in response to channel-bend expansion and downstream migration, resulting in preservation of sequences that fine upwards and downstream. Lower-bar deposits are mainly very-coarse to coarse sands with medium-scale trough cross-strata overlying basal gravels: associated radar facies are generally low-amplitude, relatively discontinuous inclined reflectors. Upper-bar deposits are mainly fine to medium sands with medium- and small-scale cross-strata and vegetation-rich layers: associated radar facies are generally moderate- to high-amplitude, laterally continuous, inclined reflectors. Large-scale inclined stratasets seen in GPR profiles resulted from episodic point-bar accretion. Abrupt lateral changes in inclination of these stratasets, and preservation of distinct unit bars (bar heads, scroll bars), lower-bar platforms and inner-bank swale fills, record discrete episodes of erosion and deposition associated with floods with recurrence intervals of decades to centuries. Such detailed 3-D description and interpretation of these large-scale features of point-bar deposits was only possible through the use of GPR profiles tied closely to cores, and through the availability of much previously collected information on channel geometry, water flow, sediment transport, erosion and deposition.

Notes: A range of large-scale dunes of oolitic calcarenite composition are exposed in the Corinth Basin of central Greece. These transverse dunes and a very large linear dune (〉 15 m high) lie within an Upper Pleistocene, transgressive marine sequence. Tidal flow, accelerated by constriction through a narrow, fault-bounded seaway, is interpreted to have generated the current velocities necessary to produce the dunes.Marine facies in the Upper Pleistocene sequence include beach to offshore conglomerates and sandstones with wave-modified sedimentary structures and herringbone cross-stratification. An offshore facies association comprises variably bioturbated siltstones and sandstones with a varied marine fauna that includes thermophile species such as scleractinian corals and Strombus bubonius. Oolitic sandstone facies also occur.Oolitic sands were apparently produced in shoal environments subject to tidal (and wave) action, and transported by dominant southerly currents over the southern part of the basin. Oolites accumulated in a linear dune 2.7 km long and 15–20 m high and in three-dimensional transverse dunes up to 10 m high having a variety of compound and simple internal geometries. The isolated, WSW-ENE-trending linear form exhibits angle of repose sedimentary dips (up to 35°) of avalanche sets on its SE flank and sets typically with dips of 15–20° to the NW. Internal high-angle discontinuities are developed in the SE-dipping lee face. It is proposed that a dominant north-to-south flow crossed over the crest obliquely, resulting in both net erosional and depositional processes on the lee flank. A subordinate (?tidal) current may have locally and or periodically crossed the dune crest in a westwards direction. A string of transverse dunes, which were located adjacent to a fault/marine terrace scarp, is interpreted to have originally coalesced to form the linear dune.The distribution of transverse and linear dunes together with the palaeogeographical reconstruction suggest that a marine connection periodically existed across the Corinth Isthmus during the Late Pleistocene due to a combination of active faulting and glacio-eustatic highstands of sea level.