Picture from jonsullivan.com
The phenomena I picked were the Moving Rocks of Death Valley.
I've documented it from http://sophia.smith.edu/~lfletche/deathvalley.html
"Actively studied for 50 years, the rocks that mysteriously move around the dried lake bed playa in Death Valley, called the Racetrack, are yet to have an unquestionable explanation for their movement.
In 1955 George M. Stanley first proposed the theory that the rocks move with the assistance of ice sheets forming after the playa surface is flooded.
There have been times when the playa is flooded with standing water up to 7 cm deep and temperatures commonly drop below freezing at the Racetrack (elevation is 3,708 feet so it has cooler temperatures than the valley floor which has the lowest elevation and the highest recorded temperature in the western hemisphere) in the winter and early spring.
In 1976 Robert Sharp and Dwight Carey disputed the ice-sheet theory. They analyzed the tracks and concluded because of track characteristics and the geometries of the tracks relative to each other that ice sheets could not have been involved in forming the tracks and moving the rocks.
Sharp and Carey also did an experiment using a circle of stakes around rocks to test the ice-sheet theory. At one time the one rock within the stakes (called "the corral") moved out leaving a distinct track; another time two rocks were placed inside the corral and the smaller rock moved out while the larger remained within the stakes. Sharp and Carey concluded that this would be an impossible result if ice was necessary for moving the rocks.
In 1976 they stated, "It is concluded that wind moves the stones when conditions are just right, that this normally happens at least every one to three years on Racetrack Playa, and that ice sheets are not necessary." (Sharp and Carey, 1976).
In 1995, John B. Reid, Jr. and other geologists from Hampshire College disagreed with Sharp and Carey's conclusion. Using data from seven Death Valley visits in the late 1980s through 1994, they support Stanley's original ice sheet hypothesis. Reid et. al. compared tracks and the similarities of tracks and doing careful mapping saw that most of the tracks formed during the 2 major movement events had congruent paths. Some tended to deviate near the end of the trail and they justified this by explaining that the ice sheet would break into smaller pieces as it melted and the imbedded rocks could separate."
I would recommend going to this site for more information and pictures.
I first heard about these rocks from an old show on the Sci-Fi channel. Many people have very good theories on the reasons that the rocks move, but none are definitive. The most important objects having to do with this phenomenon are obviously the rocks. There's nothing particularly special about the rocks themselves. They're made up of the same materials and elements commonly found in rocks from the Southwest United States.
The valley and the rocks are composed of Saline deposits, formed from evaporation of intermittent stream waters, include sodium borates and sulphates, gypsum, and rock salt, mixed with mudstones, carbonates, and floodplain sediments.
The clockwork of this phenomenon is a little harder to explain because there isn't a definitive answer to why the rocks move. Some say that there is moisture that causes the rocks to move slightly and gradually over time. Some say that ice forms and moves the stones. In any case, the process is slow and it repeats itself over and over again in order to move the stones