THE PLT OF A CESSNA 170A HAD DEPARTED ALBANY, GA VFR WITH NO FLT PLAN FOR ATHENS, GA. A CESSNA R172K FROM THE ATHENS AIRPORT WAS ENGAGED IN LOCAL FLYING. THE 172 RETD FROM DOING AIRWORK AND WAS MAKING A FULL STOP LDG. DURING HIS LANDING ROLL THE PLT REPTD THAT HIS AIRPLANE SUDDENLY YAWED 90 DEGS TO THE LEFT AND SKIDDED DOWN THE RUNWAY TO A STOP. HE STATED THAT WHEN HE EXITED HIS AIRPLANE HE SAW THE 170 RESTING ON HIS TAIL. THE 170 PLT STATED THAT HE STARTED CALLING ATHENS ATCT ABOUT 10 MILES OUT AND CONTINUED REPTG HIS POSITION UNTIL 1/2 MILE FINAL. THE PLT REPTD THAT HE DID NOT SEE THE 172 AS IT WAS DIRECTLY BELOW HIM. HE STATED THAT HIS AIRPLANE SETTLED ONTO THE 172 DURING HIS FLARE FOR LDG. THE VFR CHART, CURRENT AT THE TIME DEPICTED ATHENS AS A CONTROLLED FIELD WITH AN APT TRAFFIC AREA ALTHOUGH THE TABLE IN THE CHART LEGEND INDICATED THAT THE ATCT WAS CLOSED UNTIL FURTHER NOTICE. THE TOWER HAD BEEN CLOSED SINCE 1981.