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  • 1
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    Floodplains : Interdisciplinary Approaches (1999)
    London : The Geological Society
    Details
    Keywords: Aue ; Hochwasser ; Überschwemmungsgebiet ; Flusssystem ; Flusssediment ; Floodplains ; Plaines inondables
    Description / Table of Contents: Jan Alexander and Susan B. Marriott: Introduction / Geological Society, London, Special Publications, 163:1-13, doi:10.1144/GSL.SP.1999.163.01.01 --- Contemporary Floodplain Process --- A. P. Nicholas and S. J. McLelland: Hydrodynamics of a floodplain recirculation zone investigated by field monitoring and numerical simulation / Geological Society, London, Special Publications, 163:15-26, doi:10.1144/GSL.SP.1999.163.01.02 --- Jan Alexander, Chris R. Fielding, and Geoff D. Pocock: Flood behaviour of the Burdekin River, tropical north Queensland, Australia / Geological Society, London, Special Publications, 163:27-40, doi:10.1144/GSL.SP.1999.163.01.03 --- D. E. Walling: Using fallout radionuclides in investigations of contemporary overbank sedimentation on the floodplains of British rivers / Geological Society, London, Special Publications, 163:41-59, doi:10.1144/GSL.SP.1999.163.01.04 --- Marcel Van Der Perk, Peter A. Burrough, Adrian S. C. Culling, Gennady V. Laptev, Boris Prister, Umberto Sansone, and Oleg V. Voiteskhovitch: Source and fate of Chernobyl-derived radiocaesium on floodplains in Ukraine / Geological Society, London, Special Publications, 163:61-67, doi:10.1144/GSL.SP.1999.163.01.05 --- Basil Gomez, Dennis N. Eden, D. Murray Hicks, Noel A. Trustrum, David H. Peacock, and Janet Wilmshurst: Contribution of floodplain sequestration to the sediment budget of the Waipaoa River, New Zealand / Geological Society, London, Special Publications, 163:69-88, doi:10.1144/GSL.SP.1999.163.01.06 --- Floodplain Management, Restoration and Ecology --- W. M. Adams and M. R. Perrow: Scientific and institutional constraints on the restoration of European floodplains / Geological Society, London, Special Publications, 163:89-97, doi:10.1144/GSL.SP.1999.163.01.07 --- Elizabeth S. Andrews: Identification of an ecologically based floodway: the case of the Cosumnes River, California / Geological Society, London, Special Publications, 163:99-110, doi:10.1144/GSL.SP.1999.163.01.08 --- Nathalie E. M. Asselman: The use of floodplain sedimentation measurements to evaluate the effects of river restoration works / Geological Society, London, Special Publications, 163:111-122, doi:10.1144/GSL.SP.1999.163.01.09 --- Margriet M. Schoor, Henk P. Wolfert, Gilbert J. Maas, Hans Middelkoop, and Jurriaan J. P. Lambeek: Potential for floodplain rehabilitation based on historical maps and present-day processes along the River Rhine, The Netherlands / Geological Society, London, Special Publications, 163:123-137, doi:10.1144/GSL.SP.1999.163.01.10 --- P. J. O’Donoghue: Somerset Levels and Moors: buying off the presumptive rights of landholders to manage the land as they see fit / Geological Society, London, Special Publications, 163:139-143, doi:10.1144/GSL.SP.1999.163.01.11 --- R. R. Boar, J. J. H. Kirby, and D. J. Leeming: Variations in the quality of the thatching reed Phragmites australis from wetlands in East Anglia, England / Geological Society, London, Special Publications, 163:145-151, doi:10.1144/GSL.SP.1999.163.01.12 --- A. Hassan, T. C. Martin, and E. Mosselman: Island topography mapping for the Brahmaputra-Jamuna River using remote sensing and GIS / Geological Society, London, Special Publications, 163:153-161, doi:10.1144/GSL.SP.1999.163.01.13 --- Recent Floodplain Evolution and Deposits --- J. A. Cotton, G. L. Heritage, A. R. G. Large, and D. G. Passmore: Biotic response to late Holocene floodplain evolution in the River Irthing catchment, Cumbira / Geological Society, London, Special Publications, 163:163-178, doi:10.1144/GSL.SP.1999.163.01.14 --- Mark Dinnin and Barbara Brayshay: The contribution of a multiproxy approach in reconstructing floodplain development / Geological Society, London, Special Publications, 163:179-195, doi:10.1144/GSL.SP.1999.163.01.15 --- Stephen Crooks: A mechanism for the formation of overconsolidated horizons within estuarine floodplain alluvium: implications for the interpretation of Holocene sea-level curves / Geological Society, London, Special Publications, 163:197-215, doi:10.1144/GSL.SP.1999.163.01.16 --- A. V. Panin, A. Yu. Sidorchuk, and A. V. Chernov: Historical background to floodplain morphology: examples from the East European Plain / Geological Society, London, Special Publications, 163:217-229, doi:10.1144/GSL.SP.1999.163.01.17 --- Yingkui Zhao, Chen Wu, and XiuQing Zhang: Palaeochannels and ground-water storage on the North China Plain / Geological Society, London, Special Publications, 163:231-239, doi:10.1144/GSL.SP.1999.163.01.18 --- L. J. Bottrill, D. E. Walling, and G. J. Leeks: Geochemical characteristics of overbank deposits and their potential for determining suspended sediment provenance; an example from the River Severn, UK / Geological Society, London, Special Publications, 163:241-257, doi:10.1144/GSL.SP.1999.163.01.19 --- Ancient Floodplain Evolution and Techniques for Analysis --- Jean-Paul Bravard and Jean-Luc Peiry: The CM pattern as a tool for the classification of alluvial suites and floodplains along the river continuum / Geological Society, London, Special Publications, 163:259-268, doi:10.1144/GSL.SP.1999.163.01.20 --- John S. Bridge: Alluvial architecture of the Mississippi valley: predictions using a 3D simulation model / Geological Society, London, Special Publications, 163:269-278, doi:10.1144/GSL.SP.1999.163.01.21 --- V. P. Wright: Assessing flood duration gradients and fine-scale environmental change on ancient floodplains / Geological Society, London, Special Publications, 163:279-287, doi:10.1144/GSL.SP.1999.163.01.22 --- Paul J. McCarthy and A. Guy Plint: Floodplain palaeosols of the Cenomanian Dunvegan Formation, Alberta and British Columbia, Canada: Micromorphology, pedogenic processes and palaeoenvironmental implications / Geological Society, London, Special Publications, 163:289-310, doi:10.1144/GSL.SP.1999.163.01.23 --- K. W. Liu: Nature and distribution of heavy minerals in the Natal Group, South Africa / Geological Society, London, Special Publications, 163:311-325, doi:10.1144/GSL.SP.1999.163.01.24
    Pages: Online-Ressource (VI, 330 Seiten) , Illustrationen, Diagramme, Karten
    ISBN: 1862390509
    URL: http://sp.lyellcollection.org/content/163/1
    Language: English
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  • 2
    Electronic Resource
    Electronic Resource
    Alphabets and citations (1997)
    [s.l.] : Nature Publishing Group
    Nature 386 (1997), S. 112-113 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Sir-There is an alternative explanation for the variation in citation depending on an author's alphabet position that Tom Tregenza refers to (Nature 385,480; 1997). Variation may not be related to position in reference lists but rather to a real variation in productivity or originality of ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/386112b0
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  • 3
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    Sediment suspension dynamics and a new criterion for the maintenance of turbulent suspensions (2005)
    Oxford, UK : Blackwell Science Ltd
    Sedimentology 52 (2005), S. 0 
    Details
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The vertical component of the turbulent flow acceleration term, 〈inlineGraphic alt="inline image" href="urn:x-wiley:00370746:SED720:SED_720_mu1" location="equation/SED_720_mu1.gif"/〉, is used to determine the net positive vertical force that may support a suspended sediment load. A dimensionless criterion, Λ, is proposed for the maintenance of suspension, defined as the ratio of the maximum vertical turbulent stress to immersed weight of the suspended load above a unit bed area. In order that a suspension be maintained: 〈displayedItem type="mathematics" xml:id="di-fml-2" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:00370746:SED720:SED_720_mu2"/〉 where v ′ is instantaneous vertical turbulent velocity, σ and ρ are solid and fluid densities, respectively and m is the suspended load dry mass. The Λ criterion is dynamic, being a ratio of stresses and is analogous in this respect to Shields dimensionless stress criterion, θ, for the initiation of bedload motion. The new criterion is successful in predicting the maintenance of steady-state suspended sediment transport in open channel shear flow and deposition from non-uniform particulate density flows of wall jet type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3091.2005.00720.x
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  • 4
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    Large-scale structure of Calamus River deposits (Nebraska, USA) revealed using ground-penetrating radar (1998)
    Oxford UK : Blackwell Science Ltd
    Sedimentology 45 (1998), S. 0 
    Details
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The large-scale (i.e. bar-scale) structure of channel deposits of the braided, low-sinuosity Calamus River, Nebraska, is described using ground-penetrating radar (GPR) profiles combined with vibracores. Basal erosion surfaces are generally overlain by medium-scale, trough-cross-stratified (sets 3–25 cm thick), very coarse to medium sands, that are associated with relatively high amplitude, discontinuous GPR reflectors. Overlying deposits are bioturbated, small-scale cross-stratified (sets 〈3 cm thick) and vegetation-rich, fine to very-fine sands, that are associated with low-amplitude discontinuous reflectors. Near-surface peat and turf have no associated GPR reflectors. In along-stream profiles through braid and point bars, most GPR reflectors dip downstream at up to 2° relative to the basal erosion surface, but some reflectors in the upstream parts of bars are parallel to the basal erosion surface or dip upstream. In cross-stream profiles through bars, GPR reflectors are either approximately parallel to bar surfaces or have low-angle inclinations (up to 6°) towards cut banks of adjacent curved channels. Basal erosion surfaces become deeper towards cut banks of curved channels. These structures can be explained by lateral and downstream growth of bars combined with vertical accretion. Convex upwards forms up to 0·5 m high, several metres across and tens of metres long represent episodic accretion of unit bars (scroll bars and bar heads). Stratal patterns in channel fills record a complicated history of erosion and deposition during filling, including migration of relatively small bars. A revised facies model for this type of sandy, braided river has been constructed based on this new information on large-scale bedding structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3091.1998.00174.x
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  • 5
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    The physical character of subaqueous sedimentary density flows and their deposits (2001)
    Oxford UK : Blackwell Science Ltd
    Sedimentology 48 (2001), S. 0 
    Details
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The complexity of flow and wide variety of depositional processes operating in subaqueous density flows, combined with post-depositional consolidation and soft-sediment deformation, often make it difficult to interpret the characteristics of the original flow from the sedimentary record. This has led to considerable confusion of nomenclature in the literature. This paper attempts to clarify this situation by presenting a simple classification of sedimentary density flows, based on physical flow properties and grain-support mechanisms, and briefly discusses the likely characteristics of the deposited sediments. Cohesive flows are commonly referred to as debris flows and mud flows and defined on the basis of sediment characteristics. The boundary between cohesive and non-cohesive density flows (frictional flows) is poorly constrained, but dimensionless numbers may be of use to define flow thresholds. Frictional flows include a continuous series from sediment slides to turbidity currents. Subdivision of these flows is made on the basis of the dominant particle-support mechanisms, which include matrix strength (in cohesive flows), buoyancy, pore pressure, grain-to-grain interaction (causing dispersive pressure), Reynolds stresses (turbulence) and bed support (particles moved on the stationary bed). The dominant particle-support mechanism depends upon flow conditions, particle concentration, grain-size distribution and particle type. In hyperconcentrated density flows, very high sediment concentrations (〉25 volume%) make particle interactions of major importance. The difference between hyperconcentrated density flows and cohesive flows is that the former are friction dominated. With decreasing sediment concentration, vertical particle sorting can result from differential settling, and flows in which this can occur are termed concentrated density flows. The boundary between hyperconcentrated and concentrated density flows is defined by a change in particle behaviour, such that denser or larger grains are no longer fully supported by grain interaction, thus allowing coarse-grain tail (or dense-grain tail) normal grading. The concentration at which this change occurs depends on particle size, sorting, composition and relative density, so that a single threshold concentration cannot be defined. Concentrated density flows may be highly erosive and subsequently deposit complete or incomplete Lowe and Bouma sequences. Conversely, hydroplaning at the base of debris flows, and possibly also in some hyperconcentrated flows, may reduce the fluid drag, thus allowing high flow velocities while preventing large-scale erosion. Flows with concentrations 〈9% by volume are true turbidity flows (sensuBagnold, 1962), in which fluid turbulence is the main particle-support mechanism. Turbidity flows and concentrated density flows can be subdivided on the basis of flow duration into instantaneous surges, longer duration surge-like flows and quasi-steady currents. Flow duration is shown to control the nature of the resulting deposits. Surge-like turbidity currents tend to produce classical Bouma sequences, whose nature at any one site depends on factors such as flow size, sediment type and proximity to source. In contrast, quasi-steady turbidity currents, generated by hyperpycnal river effluent, can deposit coarsening-up units capped by fining-up units (because of waxing and waning conditions respectively) and may also include thick units of uniform character (resulting from prolonged periods of near-steady conditions). Any flow type may progressively change character along the transport path, with transformation primarily resulting from reductions in sediment concentration through progressive entrainment of surrounding fluid and/or sediment deposition. The rate of fluid entrainment, and consequently flow transformation, is dependent on factors including slope gradient, lateral confinement, bed roughness, flow thickness and water depth. Flows with high and low sediment concentrations may co-exist in one transport event because of downflow transformations, flow stratification or shear layer development of the mixing interface with the overlying water (mixing cloud formation). Deposits of an individual flow event at one site may therefore form from a succession of different flow types, and this introduces considerable complexity into classifying the flow event or component flow types from the deposits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3091.2001.00360.x
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  • 6
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    Electronic Resource
    Gravel antidunes in the tropical Burdekin River, Queensland, Australia (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Sedimentology 44 (1997), S. 0 
    Details
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The geological record is punctuated by the deposits of extreme event phenomena, the identification and interpretation of which are hindered by a lack of data on contemporary examples. It is impossible to directly observe sedimentary bedforms and grain fabrics forming under natural particle-transporting, high-velocity currents, and therefore, their characteristics are poorly documented. The deposits of such flows are exposed however, in the dry bed of the Burdekin River, Queensland, Australia following tropical cyclone-induced floods.Long wave-length (up to 19 m) gravel antidunes develop during short (days) high-discharge flows in the upper Burdekin River (maximum recorded discharge near the study reach over 25 600 m3 s−1 in February 1927). Flood water levels fall quickly (metres in a day) and flow is diverted away from raised areas of the river bed into subchannels, exposing many of the high-stage bedforms with little reworking by falling-stage currents. Gravel bedforms were observed on the dry river bed after the moderate flows of February 1994 (max. 7700 m3 s−1) and January 1996 (max. 3200 m3 s−1). The bedforms had wave-lengths in the range 8–19 m, amplitudes of up to 1 m with steeper stoss than lee faces and crest lines generally transverse to local peak-discharge flow direction. The gravel fabric and size sorting change systematically up the stoss and down the lee faces. The antidune deposits form erosive based lenses of sandy gravel with low-angle downstream dipping lamination and generally steep upstream dipping a-b planes. The internal form and fabric of the antidune gravel lenses are distinctly different from those of dune lee gravel lenses. The erosive based lenses of low-angle cross-bedded gravel with steep upstream dipping a-b planes are relatively easy to recognize and may be diagnostic of downstream migrating antidunes. The antidune gravel lenses are associated with thick (to 1 m) high-angle cross bed sets. Ancient antidune gravel lenses may be diagnostic of episodic high-discharge conditions and particularly when they are associated with high-angle cross-bedded gravelly sand they may be useful for palaeoenvironmental interpretation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3091.1997.tb01527.x
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  • 7
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    Quantifying velocity and turbulence structure in depositing sustained turbidity currents across breaks in slope (2005)
    Oxford, UK : Blackwell Science Ltd
    Sedimentology 52 (2005), S. 0 
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    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Two-dimensional experiments investigating sediment transport and turbulence structure in sustained turbidity currents that cross breaks in slope are presented as analogue illustrations for natural flows. The results suggest that in natural flows, turbulence generation at slope breaks may account for increased sand transport into basins and that the formation of a hydraulic jump may not be necessary to explain features such as the occurrence of submarine plunge pools and the deposition of coarser-grained beds in the bottomsets of Gilbert-type fan deltas. Experimental flows were generated on 0°, 3°, 6° and 9° slopes of equal length which terminated abruptly on a horizontal bed. Two-component velocities were measured on the slope, at the slope break and downstream of the slope break. Flows were depositional and non-uniform, visibly slowing and thickening with distance downstream. One-dimensional continuous wavelet transforms of velocity time series were used to produce time-period variance maps. Peaks in variance were tested against a background red-noise spectrum at the 95% level; a significant period banding occurs in the cross-wavelet transform at the slope break, attributed to increased formation of coherent flow structures (Kelvin–Helmholtz billows). Variance becomes distributed at progressively longer periods and the shape of the bed-normal-velocity spectral energy distribution changes with distance downstream. This is attributed to a shift towards larger turbulent structures caused by wake stretching. Mean velocity, Reynolds shear stress and turbulent kinetic energy profiles illustrate the mean distribution of turbulence through the currents. A turbulent kinetic energy transfer balance shows that flow non-uniformity arises through the transfer of mean streamwise slowing to mean bed-normal motion through the action of Reynolds normal stresses. Net turbulence production through the action of normal stresses is achieved on steeper slopes as turbulence dissipation due to mean bed-normal motion is limited. At the slope break, an imbalance between the production and dissipation of turbulence occurs because of the contrasting nature of the wall and free-shear boundaries at the bottom and top of the flows, respectively. A rapid reduction in mean streamwise velocity predominately affects the base of the flows and steeper proximal slope flows have to slow more at the break in slope. The increased turbulent kinetic energy, limited bed-normal motion and strong mixing imposed by steep proximal slopes means rapid slowing enhances turbulence production at the break in slope by focusing energy into coherent flow structures at a characteristic period. Thus, mean streamwise slowing is transferred into turbulence production at the slope break that causes increased transport of sediment and a decrease in deposit mass downstream of the slope break. The internal effects of flow non-uniformity therefore can be separated from the external influence of the slope break.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3091.2005.00705.x
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  • 8
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    Supply limited sediment transport in a high-discharge event of the tropical Burdekin River, North Queensland, Australia (2004)
    Oxford, UK : Blackwell Science Ltd
    Sedimentology 51 (2004), S. 0 
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    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Interactions between catchment variables and sediment transport processes in rivers are complex, and sediment transport behaviour during high-flow events is not well documented. This paper presents an investigation into sediment transport processes in a short-duration, high-discharge event in the Burdekin River, a large sand- and gravel-bed river in the monsoon- and cyclone-influenced, semi-arid tropics of north Queensland. The Burdekin's discharge is highly variable and strongly seasonal, with a recorded maximum of 40 400 m3 s−1. Sediment was sampled systematically across an 800 m wide, 12 m deep and straight reach using Helley-Smith bedload and US P-61 suspended sediment samplers over 16 days of a 29-day discharge event in February and March 2000 (peak 11 155 m3 s−1). About 3·7 × 106 tonnes of suspended sediment and 3 × 105 tonnes of bedload are estimated to have been transported past the sample site during the flow event. The sediment load was predominantly supply limited. Wash load included clay, silt and very fine sand. The concentration of suspended bed material (including very coarse sand) varied with bedload transport rate, discharge and height above the bed. Bedload transport rate and changes in channel shape were greatest several days after peak discharge. Comparison between these data and sparse published data from other events on this river shows that the control on sediment load varies between supply limited and hydraulically limited transport, and that antecedent weather is an important control on suspended sediment concentration. Neither the empirical relationships widely used to estimate suspended sediment concentrations and bedload (e.g. Ackers & White, 1973) nor observations of sediment transport characteristics in ephemeral streams (e.g. Reid & Frostick, 1987) are directly applicable to this river.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3091.2004.00616.x
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  • 9
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    Experimental turbidity currents entering density-stratified water: analogues for turbidites in Mediterranean hypersaline basins (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Sedimentology 43 (1996), S. 0 
    Details
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Experimental turbidity currents entering two-layer density-stratified water behave differently from similar currents flowing over the same topography into non-stratified water. Experiments were designed as analogues for flows entering Mediterranean hypersaline pools. In both the hypersaline pools and the experiments, the water density changes abruptly across a pycnocline. Turbidity currents generated on a platform at the level of the pycnocline behaved in one of three ways as they flowed from the platform into deeper stratified water. (1) When the bulk density of the current was less than the dense water layer, the current spread at the pycnocline. The head of the current advanced rapidly when it lost contact with the bed. Grains settling out of the current fell through the dense water layer forming an extensive deposit. In nature this behaviour will lead to ‘turbidites’ with sharp but non-erosive bases, strongly developed grading and no traction features. (2) When the bulk density of the current was greater than the dense water layer, the current continued as an underflow, plunging into the deeper water. Sedimentation lowered the bulk density of the current and the low-density interstitial fluid caused the head to loft. Low-density interstitial fluid convected from the body of the current, lofting particles into the water column. These particles were hydraulically sorted during upward transport and subsequent settling to the floor. The resulting turbidites had a more limited extent than the deposits of either non-lofting underflows or interflows. By inference from the experiments, natural deposits of this type may have local (proximal) erosion and traction features at the base and strongly graded tops. (3) In some of the currents with high bulk density, the rising turbid water reached the pycnocline and spread at that level as a secondary interflow. The tail of the turbidity current, which was less dense than the head and body of the current, flowed above the pycnocline adding momentum to the secondary interflow. The thin non-erosive graded deposit from the secondary interflow may extend beyond the deposits of the primary underflow. In all three cases (but more pronounced in cases 2 and 3) the interaction of the current with the pycnocline displaced that surface and generated a wave that was reflected back and forth from each end of the pool. The waves remobilized sediment on the ramp.
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    URL: http://dx.doi.org/10.1046/j.1365-3091.1996.d01-21.x
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  • 10
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    Ground-penetrating radar and coring used to study the large-scale structure of point-bar deposits in three dimensions (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Sedimentology 42 (1995), S. 0 
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    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    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.
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    URL: http://dx.doi.org/10.1111/j.1365-3091.1995.tb00413.x
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