DURING A CROSS COUNTRY FLIGHT, THE PILOT REPORTED THAT HE WAS TURNING AROUND TO RETURN TO HIS DEPARTURE POINT BECAUSE OF WEATHER CONDITIONS THAT DID NOT PERMIT CONTINUED FLIGHT UNDER VFR CONDITIONS. THE PILOT LAST REPORTED AT 10,500 FEET AND BETWEEN LAYERS. THE WRECKAGE WAS LOCATED AT 10,800 FEET IN MOUNTAINOUS TERRAIN THAT ROSE TO 11,000 FEET.