A PICK UP USED TO TRANSPORT THE INDIVIDUALS TO THE WORKSITE WAS DRIVING ON AN AREA WHERE TOPSOIL HAD BEEN RESPREAD AND ROCK PICKING WAS IN PROGRESS. THE DRIVER DID NOT SEE A HOLE LEFT BY A ROC K AND IT IT WITH THE PICK UP. THE PASSENGER, NOTEXPECTING THIS, WAS BOUNCED AROUND AND HIT HER HEAD ON THE ROOF OF THE PICKUP CAUSING THE INJURY.