The changes in grain size and concentration with time were studied in relatively dilute settling suspensions of varying initial concentration and constituent grain size and composition. During single grain settling in distilled water and dispersant solution, i.e., in the absence of flocculation, a narrow range of sizes at a time were lost from suspension at a rate dependent on the initial size distribution. In salt water the importance of single grain settling relative to floe settling decreased with increase in concentration. The decrease in total concentration with time due to floe settling was proportional to the minus four-thirds power of the time. The overall sorting of the sediment had some effect on the flocculation rate but the effect of grain mineralogy appeared to be minor. Comparison between the size distributions of the settled sediment and textures of recent clastic sediments and experimental turbidites indicates that the relative effectiveness of single grain and floe settling largely determines the sorting of most fine-grained as well as many sandy sediments.

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