Our ability to present the orientations of the various discontinuities and their intersections and interpret them is a prerequisite for carrying out a proper analysis of the rock mass behaviour. With the fundamentals of engineering geology covered in Chapter 1, we will continue the introduction to rock mechanics through this chapter on spherical presentation of geological data, which is a systematic method of presentation (e.g., orientation of the discontinuity planes as introduced in Section 1.5) that enables some simple stability analyses in engineering applications to be carried out.