EE WAS WORKING WITH OTHER SCALING AN AREA OF 9 EAST/K SOUTH WHEN A ROCK OR ROCKS FELL FROM AN AREA THAT WAS JUST CHECKED MOMENTS BEFORE THE INCIDENT. THEY WERE WORKING THE RIB AND DID NOT SEE ANYTHING WHICH WOULD HAVE INDICATED THERE WAS UNSTABLE ROCK. THEY WERE ABOUT 15-20 FEET FROM THE GROUND WHEN THE ROCK OR ROCKS FELL STRIKING EE SHE REC'D CONTUSIONS TO HER NECK SHOULDER ARM .