The student pilot encountered a thermal lift, and climbed to 3,000 feet. He stated in a statement to law enforcement personnel, "I got myself into a spin that I was not sure how to get out of." He further stated, "Somehow I was able to get myself out of that, and was headed back to the airport. This is where it gets vague to me. I think I started into another spin." Another glider pilot who departed 10 to 15 minutes before the student pilot stated he observed the glider about a 1,000 feet or less below him spinning to the left. He made a 360 degree turn looking for the glider and could not see it and figured the pilot recovered from the spin and flew away. Examination of the glider by a Federal Aviation Administration inspector revealed the glider collided with the ground in a nose down left wing attitude. The forward cabin area received structural damage, the left wing was pushed aft and the right wing was accelerated forward. The flaps on both wings were extended. The Pilot's Notes for the L-13 Sailplane states, the glider will stall at 30 knots with the flaps extended. No anomalies were noted with the airframe or flight controls.