Photo-sieving: A method for grain-size analysis of coarse-grained,unconsolidated bedding surfaces |
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| Authors: | Hillert Ibbeken Ruprecht Schleyer |
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| Abstract: | The photo-sieving method enables the grain-size analysis of particles > 10 mm from unconsolidated openwork bedding surfaces. The accuracy is equal to the machine-sieving method. The sediment surface is photographed in the field using a camera stand. The enlarged print is digitized for computer processing by tracing the outlines of the pebbles. From the size and shape of the projection area of the individual pebble images the computer determines the ellipsoids of revolution, classifies these ellipsoids, and establishes their grain-size distribution in percentage by weight. Thus photo-sieving differs distinctly from point-counting techniques. With the aid of photo-sieving, the surface grain-size distributions of larger sedimentary systems may be regularly mapped. Alluvial fans, braided rivers, both onshore and offshore coasts or areas of relict sediments and manganese nodules are suitable for this method. |
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| Keywords: | Grain-size Gravel Bedding surface Photography Computer |
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