ABSTRACT

Natural sediment samples consisting of a narrow size range of very fine sand were sieved in a cascadograph, essentially a stack of 20 identical sieves. The pan fraction was removed periodically during the sieving of single samples and analyzed using Fourier methods. It was found that sediment with the largest harmonic amplitudes was also that with the longest residence time within the cascadograph. That is, it takes longer for more irregularly shaped particles to pass a sieve than more equant and smooth particles. Thus, sieve analysis results are a function of the sample shape distribution as well as size distribution. Nuances of sievesize distributions may well be attributed to shape, and for detailed analysis, other sizing techniques should be used. The cascadograph is a successful nd relatively simple shape analysis tool and its results correlate with those of Fourier methods.