Downstream fining in gravel bed rivers

The special session Equal Mobility and Downstream Fining in Gravel Bed Rivers held May 8, 1989, at the AGU Spring Meeting in Baltimore, Md., examined the apparent contradiction between two observations: that bed grain size in aggrading rivers decreases downstream, mainly through selective deposition of the coarse clasts, but that measurements in gravel channels and flumes indicate that all grain sizes in a mixture are transported at the same rate, when scaled according to their proportion in the bed. If all sizes are transported at equal rates, how are the coarser clasts selectively deposited during aggradation?.