Population Breaks in Grain-Size Distributions of Sand--A Theoretical Model

Abstract

ABSTRACT The model attributing the presence of inflection points (breaks) separating straight-line segments of grain-size distributions plotted on log-probability paper to the presence of three transport populations preserved in deposits permits a correlation of environmental and genetic criteria with grain-size distributions. Analysis of a physical model of sedimentation suggests applicability of the -theorem of dimensional analysis to 10 selected physical parameters functionally related to movements of break positions which control distribution curve shapes. Application of the seven terms in a described set of dimensionless numbers generated by the model to 20 selected grain-size distribution curves illustrates systematic variations. The study leads to the conjecture that grain-size distribution can be related to specific physical aspects of the depositional process by the use of seven general terms which can be used as a basis for rigorous testing of the depositional model in the laboratory.