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  • 1
    Electronic Resource
    Electronic Resource
    Convolute lamination in modern sands of the estuary of the Oosterschelde, the Netherlands, formed as the result of entrapped air (1979)
    Oxford, UK : Blackwell Publishing Ltd
    Sedimentology 26 (1979), S. 0 
    Details
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Soft-sediment deformation structures similar to convolute lamination were found at the sandy rim of an intertidal shoal in the Oosterschelde estuary, the Netherlands. Abundant air filled cavities within upward penetrated domes suggest that reversed density stratification resulting from trapped air in some sand layers plays a role in the deformational process.Field observations show that air-filled cavities are formed within fine-grained sand; at rising tide the ground water level does not rise quickly enough to replace the interstitial air before flood water covers the sediment surface. Thus, air is trapped in the sand between the ground water level and the sediment-water interface. Because of the weight of the overlying water column and the slow downward movement of water due to capillary action, the entrapped air is compressed and eventually may attain a pressure which enables it to lift the overlying sediment. At this time bubbles are formed, often to a depth of 20 cm. Observation and experiments show that, in layers of fine sand, bubbles develop preferentially in better sorted and coarser zones. This is probably because capillary forces are greater in finer-grained and less sorted sand. Thus, water will penetrate by preference into the latter, pressing the interstitial air into the better sorted and coarser sand. The high content of air cavities in certain layers then provides the density instability responsible for the deformational process leading to the formation of convolute lamination. In the intertidal zone this appears to be a slow process that covers a number of ebb and flood cycles.Convolute lamination has been described from a number of ancient sandstones that are thought to have been deposited in shallow water, near-shore environments. In many of these cases sand size compares with that found in the Oosterschelde. Air entrapment might have played a role in the formation of certain of these occurrences of convolute lamination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3091.1979.tb00355.x
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  • 2
    Electronic Resource
    Electronic Resource
    Mechanical effects of micro-organisms on intertidal bedform migration (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Sedimentology 28 (1981), S. 0 
    Details
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Attention is called to the ability of bottom-dwelling micro-organisms such as algae to stabilize sandy sediment surfaces in non-carbonate environments and to influence sand transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3091.1981.tb01670.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Report of the Treasurer (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Sedimentology 38 (1991), S. 0 
    Details
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3091.1991.tb01870.x
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  • 4
    Electronic Resource
    Electronic Resource
    Sedimentology of a marine intermontane Pleistocene Gilbert-type fan-delta complex in the Crati Basin, Calabria, southern Italy (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Sedimentology 34 (1987), S. 0 
    Details
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The Crati Basin is a Pliocene-Holocene extensional basin filled by the progradation of different types of marine fan-delta systems. Coarse-grained Gilbert-type fan-deltas developed during the Pleistocene. They represent the sedimentary response to a strong differential uplift involving the basin margins and the basin itself. The differential uplift was responsible for the fragmentation of the basin into several sub-basins, into which these fan-deltas prograded. The protection and lateral confinement by structural highs, steep coastlines and the absence of strong tidal action in the adjacent Ionian Sea, allowed the regular progradation of these fan-deltas in the restricted gulfs and narrow embayments of the Crati Basin. For the classical Gilbert-type (fan) deltas in lacustrine settings, homopycnal inflow favours a rapid mixing of water masses and deposition of sediment close to the river mouth. In the case of the example described here, the density contrast between the sea water and the inflowing river water caused the separation of the muddy fraction from the coarse sandy and conglomeratic part of the sediment. This allowed the development of steep mud-poor coarse-grained delta foresets.Slope instability features (slump scars, conglomeratic flow slides) are fairly scarce in the proximal parts of the San Lorenzo del Vallo system. Towards the north, where protection from the Ionian Sea was less, they increase in importance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3091.1987.tb00798.x
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