 Since this effect depends on reducing friction, and not on increasing the wind drag, these ice cakes need not have a particularly large surface area if the ice is adequately thick, as the minimal friction allows the rocks to be moved by arbitrarily light winds.Reinforcing the "ice raft" theory, a research study pointed out narrowing trails, occurrence of intermittent spring systems, and absence of rocks at the end of the trails.The study identified the mountainous area that drains water towards the Racetrack Playa, while ice covered the intermittent lake.