THE PILOT OF THE CESSNA 180 DEPARTED THE HIGH DENSITY ALTITUDE AIRPORT WITH THE INTENTION OF FOLLOWING A CESSNA 185 FOR A LOCAL SIGHTSEEING FLIGHT. THE AIRCRAFT, WHICH WAS HEAVILY LOADED, WAS DESCRIBED BY A CFI ON THE GROUND AS WALLOWING THROUGH THE AIR AFTER DEPARTURE. THE AIRCRAFT APPEARED TO THE WITNESS TO BE IN SLOW-FLIGHT AT A SPEED JUST ABOVE A STALL, WITH NO APPRECIABLE RATE OF CLIMB. THE AIRCRAFT TURNED OUT OF THE PATTERN TOWARD RISING TERRAIN AND ULTIMATELY STALLED AND SPUN INTO THE TERRAIN.