On June 13, 2002, approximately 1250 Pacific daylight time, a Cessna 172K, N84840, registered to Checkerboard Air, and being operated/flown by a private pilot sustained substantial damage during an encounter with rocks and terrain while taxiing from landing at a non-airspaced landing site near Clarkston, Washington. The pilot and passenger were uninjured. Visual meteorological conditions existed and no flight plan had been filed. The flight, which was personal, was operated under 14 CFR 91, and originated from Felts Field, Spokane, Washington, earlier on the morning of the accident. The pilot reported that he "...called ahead to get details on the location of the airstrip and a description of the runway..." and "...was informed that the strip was an uphill grade and that it was their driveway and that it led up to their hangars...." Upon arrival in the vicinity of the landing site the pilot executed a flyby to assess the landing site and then proceeded to land the aircraft on the gravel driveway. After the touchdown he raised the flaps and transitioned to taxiing uphill on the gravel driveway towards the hangars. He reported that during the taxi "...I lost control of the aircraft and it started skidding to the right... eventually coming to rest into upsloping terrain off the left side of the driveway. The pilot reported that he believed the right wheel came in contact with a small berm of loose rock along the edge of the road (refer to attached statement of pilot). An inspector from the Federal Aviation Administration's Spokane Flight Standards District office interviewed the owner of the property where the landing site was situated. The owner reported that he witnessed the accident and that the "...pilot elected to land on the road that parallels the airstrip...." The owner reported that the road has a steep bank on one side and the runway on the other and that the aircraft touched down on the road satisfactorily and was taxing uphill towards the hangars "fairly fast" when the aircraft's left wingtip hit a bank along the left side of the road. The aircraft then spun left and the nose gear dropped into a ditch after which the right wing impacted terrain. The inspector reported that there was no evidence that the right main tire encountered the berm along the right side of the road (refer to attachment report of FAA Inspector).