TWO SANDS FORENSIC

Comparison of Two Sands

This presentation describes a forensic geology study of two separate samples of sand as part of a wrongful death suit. The purpose of the study was to determine if the two sand samples could have come from the same source. The legal question behind the study was whether similarity of the sands could entice someone to swim in an area even if it were posted no swimming. No names or locations are given in this presentation for privacy reasons.

One sand sample was collected from the bottom of an old stripping pit. This sand sample was poorly sorted with most of the sand consisting of quartz. Between 50 and 75 per cent of the sand grains were fine to very fine with the remainder being silt size. The grains were subangular to subrounded, suggesting that these grains have not been transported long distances by water.

The second sand sample, referred to as the "beach" sand, consists of more than 95 per cent quartz with some iron-straining and is reasonably well-sorted. The sand grains range from coarse to fine sand size. The individual sand grains are rounded to subrounded suggesting transport by water for some distance.

The difference in degree of rounding and in grain size between the two sand samples suggest that these two samples have completely different sources. The lack of similarity suggests that the "beach" sand was not related to the stripping pit and was probably brought to the area.