The pilot submitted a written statement. Approximately 15 minutes into the flight, the oil pressure gauge showed no oil pressure. The pilot performed a precautionary landing on a snow-covered hill. He examined the airplane and discovered that the sending wire had disconnected from the oil pressure gauge. He plugged it in and the oil pressure gauge functioned properly. He estimated that the snow cover was 4 inches deep. During the takeoff roll, he raised the tailwheel. The airplane then nosed-over. The pilot stated that he should have used soft-field takeoff techniques due to the snow-covered terrain.