THE GLIDER PILOT STATED THAT HE MADE HIS APPROACH TO THE LANDING AREA WITH FLAPS, A CONFIGURATION HE WAS NOT VERY FAMILIAR WITH; AS A RESULT, HE MISJUDGED THE APPROACH AND LANDED LONG. THE LANDING STRIP WAS DESCRIBED AS HILLY WITH ROUGH/UNEVEN TERRAIN, AND IT WAS SOFT IN SPOTS FROM RECENT RAINS. THE PILOT REPORTED THAT DURING THE LANDING ROLL, HE ENCOUNTERED A 'SHARP BUMP . . . A SIDEWAYS MOTION, THE LEFT WING WENT DOWN AND THE SHIP GROUND LOOPED.'