A casting procedure for reproducing coarse-grained sedimentary surfaces

摘要

In the field, the measurement of near-bed hydraulics remains problematic. Greater precision is possible in the laboratory, but, in the case of gravels, it is difficult to create a water-worked channel-bed that is realistic enough to replicate faithfully the conditions found in nature. In this paper, a technique to reproduce coarse-grained sedimentary fabrics of large areal extent is described. It involves moulding natural river-bed surfaces from which facsimiles are cast. Remarkably realistic casts with dimensions of 1 m by 2 m have been prototype surfaces with errors at millimetre scale (0.5 per cent of the microrelief). The technique has facilitated the introduction of sedimentary surfaces that incorporate natural, complex structures of grains up to cobble size into experimental channels where detained studies of near-bed hydraulics can be carried out.