gments<br >red from Pot-<br >ed bv Educa-<br >K Slings were<br > Freedom oj<br >Published by<br >erived<br >and N<br >mainly<br >cholas，<br >mbers of the<br >rms for their<br >estions: John<br >dson， Stephen<br >Mroczkowski，<br >~bert R. Stitt，<br >;eorgia) ; Ply-<br >York) ; Eiger<br >alifornia).<br >Preface<br >I met Dave McClurg in 1960 when he and his family came to settle<br >in California， where I then lived. He joined with us in the activities<br >of National Speleological Society members that included some<br >complex and fascinating explorations of some of California s most<br >interesting caves. In the years since， I have been associated with<br >Dave in other speleological pursuits. I know him as a man fasci-<br >nated by the cave environment， glad to share his knowledge and<br >feelings about this unique world with others， and as an individual<br >deeply concerned about the many destructive forces that con-<br >front the fragile subterranean world.<br > The National Speleological Society has members and chapters<br >across the whole country and has grown up alongside the develop-<br >ment of America s caves. This knowledge has included not only<br >information about the geology and biology of these caves， but<br >also the techniques of cave exploration that ensure safety and<br >comfort， and a strong concern for the protection of these caves<br >from vandalism， pollution or environmental alteration of any form.<br >Dave McClurg has played an important role in these scientific，<br >9<br ><br >