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<br />6.0 Analysis of Structural Discontinuities <br />' The stability of the rock mass that forms the highwalls of the quarry is controlled <br />by they discontinuities that exist within the rock mass. When the discontinuities <br />' intersect, wedges and blocks of various sizes develop and create the surfaces <br />along which sliding can occur. As observed throughout the quarry, the <br />' discontinuities all have a range of dip and dip direction, and therefore it is <br />possible that discontinuity orientations in a specific location of the quarry deviate <br />' from the general discontinuiiy orientations assumed for this report. <br />' 6.1 Evaluation of Discontinuity Measurements <br />' As the database for discontinuity measurements has increased, various methods <br />have been utilized to efficiently analyze the new geologic data relative to the <br />' existing data. The analysis of the discontinuity data was conducted using Dips <br />(Roascience, 2002), which is an interactive program for the analysis of <br />' discontinuity orientatations based on geological data inputs. For this study, the <br />data were evaluated with stereographic plots using a combination of contour <br />analyses and cluster analyses to determine representative dip directions and dip <br />angles for the predominant discontinuities. The contour analysis of the entire <br />' dataset (i.e., 2,863 points) resulted in a plot of density contours, which facilitated <br />deterrnination of the general discontinuity orientations (Figure 6). The cluster <br />' analysis further refined the data by utilizing an iterative approach to group the <br />data measurements into representative clusters. The nucleus of each cluster <br />represents the concentration center for the data (Figure 7). The differences <br />between each of the individual yew's analyses can best be seen on a <br />' stereographic presentation showing each of the concentration poles for the <br />clusters for multiple years analyses (Figure 8). A combination of the clusters <br />' from Figure 8 and the results of the contour and cluster analysis of the entire <br />dataset (Figure 7j were used to define the discontinuities and their orientations <br />' for use in this year's analysis. These poles are summarized in Figure 9 and are <br />presented in further detail in Table 2 below. <br />-15- <br />