. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography 162 Sl'BSTRATE RESPONSE TO HYDRAULIC PROCESS The initially small probabilities have decreased more than the initially large ones, and the resulting curve of frequency against size class will be exponential in form. The modal shift is the phenomenon of progressive sorting (Russell, 1939) whereby the deposit becomes finer down the transport path, as a consequence of the steady de- pletion of the transported material in coarser particles. In physical t
. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography 162 Sl'BSTRATE RESPONSE TO HYDRAULIC PROCESS The initially small probabilities have decreased more than the initially large ones, and the resulting curve of frequency against size class will be exponential in form. The modal shift is the phenomenon of progressive sorting (Russell, 1939) whereby the deposit becomes finer down the transport path, as a consequence of the steady de- pletion of the transported material in coarser particles. In physical terms, this means that the coarsest particles tend to get left behind whenever the bottom is eroded by a flow event that is weaker than the one that preceded it. If it is assumed that the input distribution is normal to begin with (Fig. 2, column B), and if it is assumed that the probabilities of admittance and retention vary linearly with grain size, then the mode shifts toward the fine end of the distribution as the sediment is traced down the transport path with no change in the shape of the normal curve. However, in a more realistic case, the probabilities of admittance and retention are assumed to vary exponentially with grain size; in other words, the transport rate varies exponentially with grain size. As a consequence, vector multiplication acts on the two sides of the frequency curve in a dissimilar fashion (col- umn C). The greater range of transport probabilities as- signed to the coarser sands results in greater efficiency of sorting on that side of the curve, and progressive steepening of that side, as the sediment is traced down the transport path. The sediment becomes increasingly enriched in the fine admixture at the expense of the coarse admixture (becomes fine-skewed), as well as be- coming finer down the transport path. This effect is particularly marked where the intensity of the flow field is made to decrease down the transport path (column D). Size Frequenc
Size: 1426px × 1752px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., book, bookcentury1900, bookcollectionamericana, bookleafnumber587
