Lorenz, studying the trails left by the stones, observed that one rock had collided against another and been deflected. "There was a rock trail and it looked like it hit another rock and bounced, but the trail didn't go all the way up to other the rock, like it was repelled somehow,"Lorenz told Smithsonian Magazine. In other words, there was some kind of force-field-like barrier around each rock that prevented total contact.
What would spontaneously form a barrier around a rock, then later disappear? Lorenz realized that as moisture levels changed with the seasons, a collar of ice could form around the rock. With the rest of the lakebed covered in a thin, cold-but-not-frozen sheet of water, this ice collar would enable the rock it encased to float—slightly. It would lift it to the top of the water, but the rock's bottom, the part that was resting directly on the ground, would not have ice on it. Wind could then blow the rock across the water, and the bottom of the rock would dig a furrow into the lakebed. Later the ice and water would melt and recede.
