Laserfiche WebLink
plane, but commonly <br />refe=red to as a great <br />circle (Marchak and Mitra, <br />19F18) . <br />The: dip vector is a single <br />point, like the pole, <br />except that it is platted <br />in the direction of the <br />dip. Simply put, it is <br />the: midpoint of the great <br />circle representation of <br />the: plane (Figure 2). As <br />such, it clearly depicts <br />the: dip direction and dip <br />value of the plane in <br />spzlce. The closer it is <br />to the center, the steeper <br />the dip. One advantage of <br />the: dip vector is that it <br />enelbles one to rapidly <br />vie:uali.2e the orientations <br /> e ~ e.. <br /> z~ ~~ e <br />® ~~ <br />® a <br /> ( .. 5~ <br />e <br />LQUHL+INPA STEI~OME7: C:~A%P12-81~D11T/14'BLUFP1. p1T <br />Pole Ploc <br />~~ or ststl~ . Tea <br />Fiqure 3. Computer pole plot of <br />discontinuities from Cedar Bluff, <br />Virginia. <br />of planes in space with very little training. <br />1';ach of the representations has its own advantages and uses. Poles <br />or dip vectors are used to represent individual discontinuities as <br />single points, keeping the <br />ste:reonet less cluttered <br />thzln if great circles are <br />used. On the other hand, <br />great circles are used to <br />represent slope faces so <br />that they stand out <br />clearly and the <br />relationships between them <br />and the individual <br />discontinuities may easily <br />be examined. Also, great <br />circles are useful when <br />representing clusters in <br />wedge analyses as <br />described later. Plotting <br />procedures for all of the <br />representations are <br />described in Part F. <br />® ..~ 2 .. <br />`~ e ~ e O <br />u 5~ e <br />..® ~3 <br />LQIIN.yIAPA STEAYple7: C: V1%P!2-U1~DR:AKBLUFIS.DwT <br />Dlp Uector Plot <br />Kawber of Statlo~q Iee <br />C. DISCONTINUITY CLUSTER Figure 4. Computer dip vector plot of <br />ANPII,YSI3 the same discontinuities from Cedar <br />Bluff, Virginia. <br />Unless a rock mass is <br />severely fractured, several distinct clusters will be obvious when <br />discontinuities are plotted as poles or dip vectors. The <br />orientations of discontinuities in a rock mass are related to its <br />geologic history. Traditionally, discontinuities have been plotted <br />Ste:reonet Analyses <br />Appendix A <br />l~IR-3 H <br />f)P~Rov~ .3~~-v/oy <br />