Abstract: AT APPROXIMATELY 2:30 AM ON MARCH 17, 1987, A STONE WEIGHING ABOUT 10 POUNDS BECAME DISLODGED FROM THE SIDE OF A DEEP VERTICAL SHAFT. THE STONE ORIGINATED AT ABOUT THE 120 TO 150 FOOT LEVEL, AND FELL 70 TO 40 FEET BEFORE IMPACTING UPON THE HEAD OF EMPLOYEE #1. THE STONE WAS COMPOSED OF HIGHLY ANGULAR LIMESTONE. EMPLOYEE #1 WAS WEARING A HARD HAT, BUT THE HAT DID NOT PROVIDE SUFFICIENT PROTECTION FROM SUCH A LARGE, HEAVY OBJECT. THERE WAS NO WIRE MESH OR OTHER RESTRAINING MATERIAL IN PLACE TO PREVENT OBJECTS FROM FALLING DOWN THE SHAFT. THERE HAD BEEN A CURSORY VISUAL INSPECTION OF THE SHAFT AFTER A BLAST FOUR HOURS PRIOR TO THE INCIDENT. EMPLOYEE #1 IS IN CRITICAL CONDITION WITH MASSIVE HEAD TRAUMA.