The private pilot reported he was on a personal, Title 14 CFR Part 91 flight to his private airstrip. He stated that while landing on the gravel airstrip he was compensating for a slight crosswind. He said he did not respond quickly enough to maintain directional control of the airplane, and that the left main landing gear wheel went into a shallow ditch, pulling the airplane off the runway, where it nosed over. The pilot indicated that there were no preaccident mechanical problems with the airplane. The airplane sustained structural damage to the wings and vertical stabilizer.