Particle Analysis Particle Analysis Granulometric Analysis Granulometric Analysis • Disaggregated sample passed through nested screens • Screen intervals usually at 1 ϕ or 0.5 ϕ • Weight resting on the screens summed to 100% • Plotted as a histogram or on a probability graph Phi Scale, ( Phi Scale, (ϕ) Log Log- normal distribution normal distribution ϕ = = - log log 2 (d (d mm mm ) Gaussian Distribution Gaussian Distribution • Mean diameter (Md Mean diameter (Md ϕ ) – Determined graphically as the 50 Determined graphically as the 50 th th percentile percentile of the cumulative distribution of the cumulative distribution • Sorting ( Sorting (σ ϕ ) – Determined graphically as the number of Determined graphically as the number of ϕ classes between the 16 classes between the 16 th th and 84 and 84 th th percentiles percentiles Gaussian Distribution Gaussian Distribution Sorting Parameter Sorting Parameter