The private pilot was on a Title 14, CFR Part 91, personal cross-country flight which included landing at an off airport site. The pilot said he made several low passes over the landing area prior to landing. He said he had plenty of room for a safe landing, but when it appeared the airplane was going to go off the end of the landing area he applied the brakes, and aimed for a brushy area. He reported that the brush concealed a creek with a 3 foot bank. The airplane collided with the bank, and nosed over. The pilot said an examination of the landing area revealed that the surface was wet glacial silt, and much slicker than he had anticipated. He said there were no known mechanical problems with the airplane prior to the accident. He said the airplane received substantial damage to the right wing, lift strut, and strut attachment.