GRAIN-SIZE DISTRIBUTIONS OF SEDIMENT CARRIED BY SINGLE TRANSPORTATIONMODES IN AN EXPERIMENTAL MICRODELTA SYSTEM

Grain-size distributions of three sands in single transport-mode exper iments after transport downstream from the brink of an experimental mi crodelta, are neither gaussian nor log-hyperbolic. Instead, the sands transported by avalanching and by suspension downstream of the microde lta derive many of their grain-size attributes from those of the sand fed into the flume at its upstream end. Relationships between the grai n-size distributions of individual transport modes and the texture of the 'original sand' are best demonstrated by normalizing the data to t he grain size of the 'original sand'. The experimental data suggest th at the suspension process does not prefer a peculiar size among the gr ains which can be suspended; i.e., grains present in the suspended loa d are represented in the same proportion as in the 'original sand'. Av alanching and saltating sands, however, show modified size distributio ns, even over short distances.