It is likely that many readers of this journal learned to use stereographic projection in the geometric description of rocks, their structural elements, and their discontinuities from Hoek and Bray's Rock Slope Engineering (1981) or from a textbook on structural geology. More recent texts on rock mechanics (e.g., Goodman's Introduction to Rock Mechanics, 1989; or Brady and Brown's Rock Mechanics for Underground Mining, 1993; or Wyllie's Foundations on Rock , 1999) contain detailed reviews of this aspect of structural geology in the early pages of their textbooks. Therefore, we can conclude that the use of stereonets is of importance in geological engineering practice and, by inference, to the education and training of engineering geologists, as well as those hydrogeologists whose work involves the analysis of fractures in rocks. Lisle and …