Figure 1.
The diagram shows soil property xi along the horizontal axis and depth z increasing downward. A straight line indicates the trend, while a wavy curve shows deviations from this trend. At a depth z i, the horizontal distance between the curve and trend is labelled w z i. The profile is divided into five vertical segments labelled d 1, d 2, d 3, d 4, and d 5 using dashed horizontal lines. At the bottom, the mean spacing is defined as d bar equals 1 over 5 times the sum of d i.Illustration of the rule of thumb for estimation of scale of fluctuation