Dennis Cassinelli: The walking rocks of the Fernley marsh

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 a few years ago, 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 extremely slick 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 in the mud. Some force had caused these rocks to move for a considerable distance across the mud flat and leave a distinct groove or track behind that sometimes changed direction as it 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 the rock had made as it had moved across the flat surface.

As unlikely as it may seem, 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 bed? I’ve arrived at this conclusion by the process of eliminating every other unlikely explanation.

If you look at the photograph accompanying this article, you can see by the tracks 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’s wet, you would see it’s as slick as snot. The stones were pushed across the slick mud 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 embedded in the mud or were too small to catch enough wind to sail across the surface.

This article is by Dayton author and historian Dennis Cassinelli, who can be contacted on his blog at denniscassinelli.com. All Dennis’ books sold through this publication will be at a 50 percent discount plus $3 for each shipment for postage and packaging.