Abstract: The invention is an anchoring device for releasably anchoring within a crack in a rock face, the crack having a pair of opposed crack walls. The device has a cam member, a load cable, and expansion and retraction structure. The cam member has convexly curved cam surfaces which contact respective walls of the crack. An inner end portion of the load cable cooperates with the cam member, and an outer end portion of the cable has a loop to cooperate with a separate link or rope. An intermediate portion of the cable cooperates with shoulders of the cam member in such a manner as to rotate the cam member in first direction when the cable is pulled. This increases force acting on the crack walls and augments retention of the device within the crack. The expansion structure automatically rotates the cam member in the first direction, thus tending to initiate retention of the device within the crack.