Introduction

The extraction of geologic information from the distribution of particle sizes in sediment samples has been attempted for at least one hundred years. Although some workers question the amount of information contained in size and our ability to extract such information (Ehrlich, 1983), the attempt continues. Part of the problem in the analysis of particle size is that it cannot be determined independent of particle shape. As a result, many techniques for particle size determinations have been developed and used, each measuring a different aspect of particle size or of particle behavior that is related to size. The rapid increase in computer and related technologies has spawned new size analyzers. Absorption of x rays, light transmissivity, electrical conductivity, and laser diffraction are examples of new techniques.

Coincidentally, it has become apparent that size distributions are not usually normal distributed, and many workers search for information other than mean and sorting (Klovan, 1966; Visher, 1969; Taira & Scholle, 1979; Kennedy et al., 1981). Such grain size information might be contained in subtle differences in size distributions that would be missed in half- or even quarter-phi intervals. In addition to measuring different aspects of size than do the traditional sieve and pipette analyses, automated size analyzers allow finer intervals or even individual grains to be analyzed, permitting more detailed inspection of the size distributions.

An additional class of sizing techniques is based on the analysis of data obtained in an image, and is referred to herein as image analysis size (IAS).