As I travel around the Nevada deserts and mountains, I sometimes find things out there that defy description and logic. When I was working as an inspector on a highway construction project on Interstate 80 near Fernley recently, I encountered one of these strange and seemingly unexplainable enigmas.
Much of northwestern Nevada was once covered with a huge freshwater lake known as Lake Lahontan. If you look closely at the hills and mountains along Interstate 80 between Fernley and Lovelock, you can see many parallel horizontal lines that mark the water level of ancient Lake Lahontan through thousands of years of fluctuating water levels. Natural climate changes have caused the water level to drop over the last several thousand years to the point where the former lake is now mostly desert. Sometimes during a particularly wet season, some of the desert lowlands once again accumulate a few inches of water.
The lake bottom consists of a fine silt mixed with alkali that becomes slick as axle grease when it gets wet. Such was the case during the spring of 2009 when I happened to notice some rocks and small boulders out on one of these mud flats that seemed to have moved across the mud leaving a distinctive irregular path or track behind. There were no footprints or vehicle tracks anywhere near the rocks or the tracks they had made. Some force had caused these rocks to move for a considerable distance across the mud flat and leave a distinct groove or track behind where it had traveled.
I stopped alongside the highway and walked out to the edge of the mud flat which at that time had begun to dry out and crust over. The surface of the mud was still too soft to support my weight without leaving footprints in the soft mud under the crust. Much of the surface of the mud had a white powder of alkali dust that was especially noticeable in the tracks that the rock had made as it had moved across the flat surface. At other places alongside this same section of highway, I noticed places where cars had ventured too far out onto the muddy surface and had sunk down to the axles. Evidence of tow truck assistance was visible indicating help was needed to remove these vehicles.
The question remains, how could these rocks have moved across the surface of the lakebed leaving the distinctive irregular track behind them as they moved? Any outside assistance to motivate the rocks would have left a mark in the soft mud just as the moving rocks had done. There had to be some motivating force to push the rocks across the mud, but it is difficult to wrap one’s imagination around the problem to arrive at an answer.
I have a theory that may explain this phenomenon after dwelling on this enigma for over two years of deep concentration. As unlikely as it may seem, I believe the motivating force that moved the rocks was the wind. You may ask how can the wind even begin to shove a rock around on the surface of a muddy lake? I have arrived at this conclusion by the process of eliminating every other unlikely explanation.
If you look at the photograph, you can see by the tracks that the rock made several stops and direction changes. Desert winds often change direction and intensity. If you were to feel a handful of the mud from the surface of this lake when it is wet, you would see that it is as slick as snot. Just like a curling stone sliding across the ice, the stones were pushed across the slick mud by being pushed by gusts of wind that changed direction and left not a mark except the track of the stone itself. Some of the other stones in the photograph were either imbedded in the mud or were too small to catch enough wind to sail across the surface. I have photos of other walking rocks that seem to confirm this theory.