On September 11, 2000, at 1230 hours Pacific daylight time, a Cessna 172L, N84828, veered off runway 31, stuck a berm, and nosed over after landing at Gnoss Field, Novato, California. The airplane, operated by Air Ward, Inc., under the provisions of 14 CFR Part 91, sustained substantial damage. The student pilot, on an unsupervised solo flight, received minor injuries. Visual meteorological conditions prevailed for the instructional flight and no flight plan had been filed. The local area flight departed from the accident airport about 1215. In the student pilot's written statement to the Safety Board, he stated that he was practicing touch-and-go takeoffs and landings, and had started flying about 1030 the morning of the accident. This was the last landing of the day after flying for about 2 hours. On the landing rollout the airplane started to drift to the left. The pilot made sure that he was not dragging the left brake by shaking his feet. The airplane rotated 360 degrees around its vertical axis and scared him so that he did not apply the brakes. At this point the airplane was rolling on the grass in-between the runway and taxiway. He added power to abort the landing but the airplane struck something and became inverted. According to a Federal Aviation Administration (FAA) inspector, who conducted an on-scene investigation, the airplane traveled across the grass, across a parallel taxiway, and across a drainage ditch. He observed that the far side of the ditch had a raised levee along its bank. After crossing the ditch the airplane struck the levee with the propeller, nose, and nose landing gear. The FAA inspector observed tire marks about midfield on the runway. The right main and nose landing gear made a left-curving track. Between the runway and parallel taxiway he observed the first contact of the left main landing gear. At that point there was no further curvature of the tire marks, which continued straight into the ditch. ADDITIONAL INFORMATION The FAA inspector reported that the student pilot's flight instructor had not endorsed him for solo flight in a Cessna 172.