Figure 8.18a,b: Figure a) is the same data shown in Figures 8-16a and 8-17 except with the data located correctly on a two dimensional contour map. The variance of the data set is exceeded near the middle of the figure, but at longer ranges substantial variation can be seen. The greatest variance has a NE-SW trend. Figure b) is the same data shown in Figures 8-16b except with the data located correctly on a two dimensional contour map. The variance of the data set is exceeded near the middle of the figure, and because of the large half-angle the results are nearly isotropic.