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Data from over 80 boreholes have been used together with the surface geology to interpret the subsurface structure and stratigraphy of the Corallian to Gault (Upper Jurassic to Lower Cretaceous) sediments in the Vale of the White Horse, between Faringdon and Wantage in West Oxfordshire. The gentle regional dip to the SSE of the sediments in this area is interrupted by two major features. The first is the Faringdon Fault, first defined at outcrop just east of Faringdon. This has been traced SE from the outcrop extent for at least 8 km in the subsurface towards Wantage. It has an estimated maximum downthrow to the SW of ca 40 m. Contrary to previous interpretations, this fault was probably active during Kimmeridge Clay deposition. The second feature is the Faringdon Trough, an erosional palaeovalley filled with at least 50 m of marine Lower Greensand sediments. The Trough trends SSE from Faringdon and cuts deeply through the Kimmeridge Clay to reach the underlying Corallian. A subtle structural feature, here named the Baulking Fault, has a throw of < 10 m and its movement was probably pre-Cretaceous, but it seems to have influenced the path and geometry of the Faringdon Trough, dividing it into two segments. Contrary to previous interpretations, subsurface mapping suggests that the main Trough has a broad U-shape in cross-section with a planar base where it rests on resistive Corallian limestone. Along its margins depositional dips of up to 9° have been widely recorded in the Lower Greensand sediments. [ABSTRACT FROM AUTHOR]

Abstract This work is the first geomorphological analysis of La Narse de la Sauvetat , a hydromorphic basin located in the southern Limagne plain (French Massif Central) which had never been studied despite its great palaeoenvironmental interest. We explore the potential of its sedimentary archives to provide valuable data on Holocene geomorphic dynamics and their sensitivity to local and regional hydro-climatic changes. In order to characterize the nature and the morphostratigraphic and pedosedimentary evolution of the basin, we used an integrative approach involving geomorphological mapping, hand auger stratigraphic cross-sections, topographic analysis based on LiDAR data and stereophotogrammetric reconstruction, geophysical prospection and radiocarbon dating. Results revealed a palaeotopography fossilized under 6 m of sedimentary infilling, with a clear shift from fluvial to hydromorphic conditions circa 2800 cal BCE, separated by a level with colluvial and lacustrine features. A detailed analysis of the eastern border of the basin also suggests the existence of a former open valley in place of the current closed depression, now locked in by a topographic threshold forming a dam. The sedimentary aggradation of the basin started with an alluvial phase during the Upper Pleistocene and probably continued into the Middle and Late Holocene, consistently with regional alluvial dynamics. In the early Subboreal, a massive landslide occurred on the western slopes of the Puy-de-Corent volcanic plateau, thereby damming the valley and forming a closed depression. This episode coincided with the mid-Holocene climatic shift and an associated phase of slope instability and increased landslides in Western Europe due to changing climatic conditions. This depression evolved into a hydromorphic basin with several high energy hydro-sedimentary episodes after 2800 cal BCE; however hydro-sedimentary conditions gradually became more stable towards the Late Holocene. Around 500 cal CE, the drainage deteriorated towards palustrine conditions and caused the formation of a marsh and its consequent evolution into a shallow lake throughout the Middle Ages. This lake was drained in the late XVIIIth Century. The long-term sedimentary record of La Narse de la Sauvetat , sensitive to climatic instability periods of the Middle Holocene, makes this landslide-dammed basin a valuable site with an important potential to further development of palaeoenvironmental and geoarchaeological studies. Graphical abstract Unlabelled Image Highlights • A palaeovalley was found under Pleistocene and Holocene alluvio-colluvial sediments. • A landslide dammed the valley in the early Subboreal, forming a short-lived lake. • The depression became hydromorphic between 2800 cal BCE and late Antiquity. • The basin was a marsh then a shallow lake during the Middle Ages. • La Narse de la Sauvetat has high potential for further palaeoenvironmental research. [ABSTRACT FROM AUTHOR]

Abstract: The Sydney Harbour crossing is a key element of Sydney Metro City & Southwest, which includes 15.5 km of twin tube running tunnels extending from Chatswood at the north through to Sydenham, south of the Central Buisness District (CBD). One of the key features is the 1 % length of the alignment that passes under Sydney Harbour. The rest of the alignment is through rock, but the harbour crossing is designed to pass through harbour sediments and mixed face conditions undersea. An in depth study and analysis was required to confirm the feasibility of the safe construction of this short length of the tunnel in sub‐aqueous, soft ground conditions. It was necessary to carry out detailed, targeted investigation of the ground to enable the selection of an appropriate tunnelling technique for constructing the tunnels. [ABSTRACT FROM AUTHOR]

Un-fragmented stratigraphic records of late Quaternary multiple incised valley systems are rarely preserved in the subsurface of alluvial-delta plains due to older valley reoccupation. The identification of a well-preserved incised valley fill succession beneath the southern interfluve of the Last Glacial Maximum Arno palaeovalley (northern Italy) represents an exceptional opportunity to examine in detail evolutionary trends of a Mediterranean system over multiple glacial-interglacial cycles. Through sedimentological and quantitative meiofauna (benthic foraminifera and ostracods) analyses of two reference cores (80 m and 100 m long) and stratigraphic correlations, a mid-Pleistocene palaeovalley, 5 km wide and 50 m deep, was reconstructed. Whereas valley filling is chronologically constrained to the penultimate interglacial (Marine Isotope Stage 7) by four electron spin resonance ages on bivalve shells ( Cerastoderma glaucum), its incision is tentatively correlated with the Marine Isotope Stage 8 sea-level fall. Above basal fluvial-channel gravels, the incised valley fill is formed by a mud-prone succession, up to 44 m thick, formed by a lower floodplain unit and an upper unit with brackish meiofauna that reflects the development of a wave-dominated estuary. Subtle meiofauna changes towards less confined conditions record two marine flooding episodes, chronologically linked to the internal Marine Isotope Stage 7 climate-eustatic variability. After the maximum transgressive phase, recorded by coastal sands, the interfluves were flooded around 200 ka (latest Marine Isotope Stage 7). The subsequent shift in river incision patterns, possibly driven by neotectonic activity, prevented valley reoccupation guiding the northward formation of the Last Glacial Maximum palaeovalley. The applied multivariate approach allowed the sedimentological characterization of the Marine Isotope Stage 7 and Marine Isotope Stage 1 palaeovalley fills, including shape, size and facies architecture, which revealed a consistent river-coastal system response over two non-consecutive glacial-interglacial cycles (Marine Isotope Stages 8 to 7 and Marine Isotope Stages 2 to 1). The recurring stacking pattern of facies documents a predominant control exerted on stratigraphy by Milankovitch and sub-Milankovitch glacio-eustatic oscillations across the late Quaternary period. [ABSTRACT FROM AUTHOR]

The Aptian Pre-Salt sedimentary succession cropping out in Cangulo palaeovalley onshore Namibe Basin (Angola) was studied by a combination of field and analytical techniques to constrain the sedimentary and diagenetic evolution of the uppermost sag sequence of the South Atlantic passive margin. Field observations allows definition of four transgressive-regressive cycles characterised by fluvial to tidal-influenced mixed clastic-carbonate and carbonate-dominated deposits, that locally show evidence of evaporite dissolution; highlighting that evaporite deposition started earlier than deposition of the regional South Atlantic Loeme-Bambata evaporite formations. Two separate pre-salt carbonate units have been differentiated within the Cangulo Fm; i) a lower transitional to marginal marine, and ii) a younger upper non-marine freshwater travertine system, that is documented for the first time in the west African margin. Transgressive-regressive cycles control the early diagenesis of the tidal carbonates that include dolomitization due to mixing fluids during transgressions, and karstification due to evaporite dissolution by meteoric water circulation during regressive events. Clastic supply appears to have been completely shut down during carbonate deposition, suggesting major climatic change associated with carbonate deposition. During the lowstand between the two carbonate units, fluid flow through Cangulo palaeovalley was re-established resulting in extensive karstification and formation of a large-scale erosional unconformity that is interpreted to be time equivalent to an intra Chela-Cuvo Fm. event. The top of the studied succession corresponds to the transgressive deposits of the Bambata evaporites that are not preserved in the Cangulo palaeovalley due to its erosion but are regionally developed. The results of this study can be directly linked to along strike age equivalent Pre-Salt successions cropping out in the Namibe, Benguela and Kwanza basins, and directly offshore Angola and Brazil using well and seismic data. These new data shed important new light and constraints on the depositional and diagenetic evolution of the complex Pre-Salt reservoir systems of the South Atlantic, and the depositional and bathymetric setting at the time of onset of the main south Atlantic evaporite deposition. [Display omitted] • This manuscript describes the sedimentology and diagenesis of pre-salt (upper sag) deposits onshore Namibe Basin (Angola). • It includes a detailed study of the pre-salt carbonates including non-marine freshwater travertine systems. • This work presents new paleogeographic reconstructions of the Pre‐Salt succession of the onshore Namibe Basin. • It provides new constraints on the overall setting from the sag to main evaporite deposition period in the South Atlantic. [ABSTRACT FROM AUTHOR]

The Ombrone palaeovalley was incised during the last glacial sea-level fall and was infilled during the subsequent Late-glacial to Holocene transgression. A detailed sedimentological and stratigraphic study of two cores along the palaeovalley axis led to reconstruction of the post-Last Glacial Maximum valley-fill history. Stratigraphic correlations show remarkable similarity in the Late-glacial to early-Holocene succession, but discrepancy in the Holocene portion of the valley fill. Above the palaeovalley floor, about 60 m below sea-level, Late-glacial sedimentation is recorded by an unusually thick alluvial succession dated back to ca 18 cal kyr bp. The Holocene onset was followed by the retrogradational shift from alluvial to coastal facies. In seaward core OM1, the transition from inner to outer estuarine environments marks the maximum deepening of the system. By comparison, in landward core OM2, the emplacement of estuarine conditions was interrupted by renewed continental sedimentation. Swamp to lacustrine facies, stratigraphically equivalent to the fully estuarine facies of core OM1, represent the proximal expression of the maximum flooding zone. This succession reflects location in a confined segment of the valley, just landward of the confluence with a tributary valley. It is likely that sudden sediment input from the tributary produced a topographic threshold, damming the main valley course and isolating its landward segment from the sea. The seaward portion of the Ombrone palaeovalley presents the typical estuarine backfilling succession of allogenically controlled incised valleys. In contrast, in the landward portion of the system, local dynamics completely overwhelmed the sea-level signal, following marine ingression. This study highlights the complexity of palaeovalley systems, where local morphologies, changes in catchment areas, drainage systems and tributary valleys may produce facies patterns significantly different from the general stratigraphic organization depicted by traditional sequence-stratigraphic models. [ABSTRACT FROM AUTHOR]

The southeastern North Sea was a sub-aerially exposed periglacial environment during the late Weichselian. At that time, the approximately 210 km long and 40 km wide SE–NW trending Elbe Palaeovalley (EPV) was the main conduit for meltwater from the southern margin of the Scandinavian ice sheet and rivers draining the North European plain. Only few studies investigated the environmental organization of the Northwest European shelves during deglacial sea level rise resulting in vague reconstructions of the drainage systems. Here, a detailed analysis of sediment echo-sounder data and core samples are presented to study the EPV morphology and stratigraphic infill. The valley base is about 65 m below the present sea-level. This SE-NW palaeo-drainage with its braided system developed during the MIS 2 sea level fall and lowstand in a periglacial environment. During deglacial sea-level rise, the EPV evolved into an estuary with tributaries, intertidal and subtidal flats. After the early Holocene (∼10 cal ka BP), ongoing sea-level rise drowned the EPV system which became the major sedimentary trap in the southern North Sea. Successive sea level rise and associated changes in the hydrodynamic regime led to three stages of shelf organization that were recorded in the valley infill successions: (1) shallow basin with restricted connections to Atlantic water; (2) the southwestern connection with the Dover Strait; (3) the open marine environment at 5.8 cal ka BP after the drowning of Dogger Bank. • Seismic coverage of a 210 km long and ∼40 km wide Elbe Palaeovalley (ice-marginal valley during MIS 2) reveals valley infill succession by unprecedented data set. • Northwestward drainage pathways utilized by rivers and meltwater from southern Scandinavian Ice Sheet was mapped. • Early valley infill successions reflect the evolution of hydrodynamic regime in the southern North Sea since late Pleistocene. • After the sea-level high stand around ∼5.8 cal ka BP, bottom currents dynamics increased and sandy drift sediments capped the valley infill. [ABSTRACT FROM AUTHOR]

The Gildirli Formation is the oldest Neogene rock unit in the Adana Basin and was formed prior to the regionally extensive Early Miocene marine transgression. These coarse clastic red-beds provide important evidence about the causes and early phases of filling in this large trough, because the Gildirli Formation sediments fill an irregular palaeotopography carved out of Palaeozoic and Mesozoic basement rocks. Detailed study of the Gildirli Formation reveals the existence of at least two alluvial fans supplied from different source areas. A northeastern fan, exposed around Gildirli Village, was fed by streams draining an area of ophiolitic mélange, Mesozoic and older limestones, and fills an irregular palaeomorphology around and northeast of Gildirli. The southwestern fan, in the Nergizlik area, is dominated by debris flow and sheet flow rudites derived from an area of entirely carbonate bedrock. The lower part of the southwestern fan is characterised by well-bedded carbonate breccias and conglomerates that occupy deep, steep-sided palaeovalleys with approximate E-W trends (parallelling the main basin-margin), whereas higher parts of this fan are muddier and show channelised fluvial and floodplain attributes. The two fans display different provenance characteristics and evidently were fed into an intervening pre-existing depression, probably tectonically controlled. The Lower to Middle Miocene sediments that succeed the Gildirli Formation fan clastics on this basin margin form a mosaic of facies associations, partly contemporaneous and partly diachronous. These include a mixed clastic-carbonate unit (Kaplankaya Formation) of mainly shallow marine character, a reefal to platform carbonate unit (Karaisalı Formation), and a coarse clastic submarine fan system (Cingöz Formation) together with its coeval deep-marine shales (Güvenç Formation). The limestone bodies of the Karaisah Formation in this area display clinoformal geometries that accord with a backstepping pattern and also attest to pre-existing fault control of the steep basin margin. The western part of the partly contemporaneous Cingöz Formation submarine fan system has been supplied through a feeder-channel that now occupies the palaeovalley depression inherited from pre-Gildirli Formation times, The palaeovalley system shows a margin-parallel trend and might have been developed before the deposition of the Gildirli Formation by extensional tectonics. Thus the location, geometry and orientation of this sector of the mid-Miocene submarine fan appears to have been determined by the tectonically mediated pre-Miocene/Early Miocene palaeomorphology. [ABSTRACT FROM AUTHOR]

Subaerial exposure beside the Wandandian Creek channel during the last glacial maximum led to the development of red and orange mottling and, in some areas, produced a palaeosol over the Pleistocene land surface. Incision of the palaeo-Wandandian Creek, during the Late Pleistocene, formed a relatively deep steep-sided channel partially infilled with medium-grained fluvial sand. This palaeovalley became drowned as the post-glacial marine transgression impounded the western portion of St Georges Basin and the basal prodelta/lagoonal mud facies was deposited from ca 7 ka. The Wandandian Creek delta prograded down the palaeovalley and reached the study area &nvsim;3500 – 4000 years ago with the deposition of delta-front sandy silt and the overlying prograded sand facies. The subaerial portion of the delta is characterised by well-developed floodplains, levees, mouth bars and backswamps. Dredging in Wandandian Creek and land clearing for rural and urban development have had little long-term effect on the growth and morphology of Wandandian Creek delta. [ABSTRACT FROM AUTHOR]

The Eocene succession filling palaeovalleys in the northeastern Eucla Basin, South Australia, is interpreted using facies and sequence-stratigraphic models based on relative sea-level changes. The dominantly fluvial sediments were deposited in incised valleys which graded basinwards to an estuarine coastal plain under warm and humid palaeoclimatic conditions. Sedimentological examination suggests a tidal influence in this fluvial succession. Fluvial–estuarine-shoreline facies associations can be recognised in these (Eocene) sequences, each of which comprises a diverse assemblage of lithofacies that can be grouped into lowstand and/or transgressive and highstand system tracts. Since the palaeorivers had hydrological connection with the sea, deposition was dominantly controlled by sea-level changes. Results of the study indicate that two third-order Eocene eustatic cycles have largely controlled sedimentation. The resulting key surfaces (unconformity, and transgressive, tidal/wave ravinement, and maximum flooding surfaces) bound depositional sequences which extend over significant areas and may be used in basin-wide correlations of stratal packages. [Copyright &y& Elsevier]

In the Gargaf area, the stratigraphic architecture of the Late-Ordovician glacial drift results from successive glacial erosion events, with the location of the main glacial valleys partly controlled by inherited Panafrican structural trends, and by the existence of glacio-isostatically induced fault-related depocentres. Four laterally discontinuous, depositional units correspond to the filling of palaeovalleys. Each of the corresponding basal bounding surfaces was incised during a major ice front advance, reaching at least the northern Gargaf (>28°S). The bulk of the glacial record is made up of fluvial to shallow-marine sediments deposited in relatively distal glacial environments. Each unit, which recorded a glacial-interglacial climatic cycle, can be used for correlation throughout the Murzuq Basin and even at the scale of the North Gondwana platform. To cite this article: J.-F. Ghienne et al., C. R. Geoscience 335 (2003). [Copyright &y& Elsevier]

The Sis conglomerate body represents the Middle Eocene to Oligocene transfer-zone trunk palaeovalley fill of the Sis fluvial system, a drainage system established within the Pyrenees during Late Palaeocene times. The spatial stability of the fluvial transfer zone (active for at least 38 My), and hence the longevity of its aggradational palaeovalley component (>19·5 My), was controlled by its location between long-lived pre-existing structures. Coarse-grained fluvial facies dominate the palaeovalley fill, with alluvial fan facies shed from its defining marginal structures. The detailed sedimentology of very proximal fluvial facies deposited within the dominantly erosional realm of an active mountain belt has rarely been documented before because of their poor preservation potential. The Sis conglomerate body contains a robust internal stratigraphy with stratigraphic units defined by distinct bounding surfaces, across which there are pronounced changes in facies and provenance. These mark the reorganization of the headward portions of the Sis fluvial system during the evolution of the Pyrenean Axial Zone antiformal stack. Major changes in discharge resulted, demonstrating the highly variable nature of even mountain belt-scale fluvial systems when viewed on timescales of several to tens of millions of years. Provenance details indicate that initial unroofing of Hercynian granitoids, situated within the Pyrenean Axial Zone, occurred around 54·5 Ma (early Ypresian) immediately before the first significant exhumation event within the drainage basin of the Sis fluvial system. This is earlier than previously constrained by apatite fission track studies. Rock uplift accelerated in the Lutetian and Bartonian with the initial aggradation of the palaeovalley fill (the Cajigar and Cornudella Formations and Sis One and Two Members). This became marked in the Priabonian (Sis Three and Four Members), with significant activity on local structures including the Morreres... [ABSTRACT FROM AUTHOR]

The influence of palaeodrainage characteristics, palaeogeography and tectonic setting are rarely considered as controls on stratigraphic organization in palaeovalley or incised valley systems. This study is an examination of the influence of source region vs. downstream base level controls on the sedimentary architecture of a set of bedrock-confined palaeovalleys developed along the distal margin of the Alpine foreland basin in south-eastern France. Three distinct facies associations are observed within the palaeovalley fills. Fluvial facies association A is mainly dominated by poorly sorted, highly disorganized, clast-to-matrix-supported cobble-to-boulder conglomerates that are interpreted as streamflood deposits. Facies association B comprises mainly yellow siltstones and is interpreted as recording deposition in an estuarine basin environment. Estuarine marine facies association C comprises interstratified estuarine siltstones and clean, well-sorted washover sandstones. The sedimentary characteristics of the valley fill successions are related to the proximity of depositional sites to sediment source areas. Palaeovalleys located proximal to structurally controlled basement palaeohighs are entirely dominated by coarse fluvial streamflood deposits. In contrast, distal palaeovalley segments, which are located several kilometres downstream, contain successions showing upward transition from coarse fluvial facies into estuarine central basin fines, and finally into estuarine-marginal marine facies. Facies distributions suggest that the fluvial deposits form wedge-shaped, downstream-thinning sediment bodies, whereas the estuarine deposits form an upstream-thinning wedge. The vertical stacking of fluvial to estuarine to marginal marine depositional environments records the fluvial aggradation and subsequent transgression of relatively small bedrock-confined river valleys, which drained a rugged, upland terrain. Facies geometries suggest that a fluvial sediment wedge... [ABSTRACT FROM AUTHOR]

The northern margin of the Carpathian basins and their closest foreland are not preserved nowadays being partly destroyed by the subduction processes, and partly hidden under several kilometres thick cover of overthrusted Carpathian nappes and autochthonous Miocene deposits. Seismic data show along the whole arch of the Carpathian orogene lowered areas that form elongated structures in the basement, approximately perpendicular to the front of the overthrust. These structures were interpreted as palaeovalleys incised in an uplifted basin margin prior to the overthrust of folded Carpathian nappes. Studies of their sedimentary sequences, for these profiles located at the depths accessible by the boreholes, have yielded ambiguous results so far. One such a palaeovalley filled with initial stage deposits was detected in the vicinity of Rzeszów, SE Poland. Organic-rich, fine-grained deposits from the middle part of this sequence yielded palynomorphs allowing their dating. We present timing of the Rzeszów palaeovalley formation based on palynological interpretations and comparison with regional geology of the Carpathian domain. • Palaeovalley origin reflects orographic differences between foreland and flysch basins. • Fine-grained fill of palaeovalley studied yielded sporomorphs allowing its timing. • Late Cretaceous palynomorphs date beginning of palaeovalley incision. • Oligocene lacustrine-marshy environment ceased palaeovalley fulfilment. • Palaeovalley timing correlates with increased chaotic deposits accumulation in Carpathian basins. [ABSTRACT FROM AUTHOR]

Stacked fluvial distributary channel deposits and palaeovalley fills can form major, multi storey sand bodies with similar thicknesses, and with lateral extents often greater than a single exposure. Consequently, they can be difficult to tell apart from one another using outcrop data. This study addresses this problem by quantitatively analysing the architecture of five stacked fluvial distributary channel deposits and two palaeovalley fills from the Pennsylvanian Pikeville and Hyden formations of the central Appalachian Basin, USA. The a priori interpretation of the sand bodies as stacked distributary channels and palaeovalley fills is possible because a robust in-place coal seam correlation framework allows for the recognition of different basin-scale architectures for each type – aspect ratios <1000 and envelopes of fluvial and deltaic strata for stacked distributary channels, and aspect ratios >1000 and a regional basinward facies shift at the bases of palaeovalley fills. Sand body thickness, storey thickness, position and length of storey contacts within the sand body are similar in both types. However, they can be distinguished by different up-system to down-system changes in their respective architectures. Stacked distributary channel sand bodies thin down system, display a decrease in storey thickness, an increase in the mean position of storey heights in the sand body and a decrease in the length of storey contacts. These trends are the result of down-system decrease in channel size, and confinement associated with radially distributive fluvial systems. Palaeovalley fill sand bodies thicken down-system, display an increase in storey thickness, a decrease in the mean position of storey heights, and a decrease in the length of storey contacts. The increase in sand body and storey thickness are the result of down-system increases in original channel size, consistent with trunk axial fluvial systems fed by tributaries that predominate during valley-formation. The down-system increase in amalgamation reflects a down-system decrease in accommodation, from the higher subsidence rate active margin of the basin, and is therefore not necessarily characteristic of palaeovalley fill architectures in all basin settings. This study emphasises the requirement for detailed correlation work and quantitative analysis of external and internal architectures before the interpretation of sand bodies as stacked distributary channels or palaeovalley fills. [ABSTRACT FROM AUTHOR]

Integrated geoscientific datasets have contributed to an understanding of the Tertiary palaeovalleys once draining the Gawler Craton. Systematic investigations of both the shape and depth of the channels are based on interpretations from field exposures, a compendium of geological and drilling data, computer modelling of ancient landscapes, topographic and evaluated digital elevation models, remote sensing imagery, magnetics, seismic, gravity, airborne and transient electromagnetics, and radiometrics. Physical property contrasts that exist between the channel sediments and the underlying bedrock, for example, can be differentiated by geophysical methods to locate the incised-valley thalweg. Evidence from sedimentology is combined with evidence from other geological and geophysical characteristics to arrive at a general reconstruction of palaeovalley architecture and history. The palaeovalleys were originally incised into the weathered pre-Tertiary landscape of mostly weathered basement, and Tertiary fluvial, lacustrine, estuarine and even marine sediments accumulated during the Eocene and Miocene. Marine influence extended at least 100 km up the palaeovalleys during at least three major transgressions in the Eocene and Miocene intervals. Major sedimentary phases occurred in the Paleocene to Early Eocene, Middle to Late Eocene, Oligocene to Early Miocene, and Middle Miocene to Early Pliocene times. [ABSTRACT FROM AUTHOR]