THE CESSNA 172 HAD ENTERED THE PATTERN ON DOWNWIND AND WAS ESTABLISHED ON A LONG FINAL FOR RUNWAY 10L. THE CESSNA 150, WHICH WAS RETURNING FROM AN INSTRUCTIONAL FLIGHT, WAS OBSERVED EXECUTING A CLOSE IN BASE LEG AND DESCENDING STEEPLY. THE CESSNA 150'S LEFT WING IMPACTED THE CESSNA 172'S DORSAL FIN AND VERTICAL STABILIZER ON SHORT FINAL. THE CESSNA 172 WAS OBSERVED TO COMPLETE APPROXIMATELY 270 DEGREES OF A LOOP BEFORE IMPACTING THE GROUND. THE CESSNA 150 ROLLED LEFT AND IMPACTED THE GROUND IN A NOSE LOW INVERTED ATTITUDE. BOTH AIRCRAFT HAD ONLY THEIR SINGLE ANTI COLLISION BEACONS OPERATING BUT NOT THEIR TAXI/LANDING LIGHTS. THE CESSNA 172'S STROBE LIGHT WAS NOT SWITCHED ON AT THE TIME OF THE ACCIDENT. THE SUN'S ELEVATION WAS DETERMINED TO BE 5 TO 7 DEGREES ABOVE THE HORIZON AT AN AZIMUTH OF 212 TO 215 DEGREES MAGNETIC.