What happened
The incident occurred during the landing phase of flight. The private pilot was operating a tailwheel-equipped airplane when attempting to land on a rough and uneven gravel bar. As the aircraft touched down and entered the landing roll, the main landing gear wheels encountered a depression within the gravel surface.
The pilot reported that he was unable to maintain directional control or prevent the aircraft from nosing over due to this terrain irregularity. The event resulted in structural damage to the airplane. The pilot stated that there were no preaccident mechanical problems with the aircraft prior to the incident.