This Sounds Totally Mad,

a stream that runs for 15 minutes then stops for 15 minutes,

and then starts again naturally! photograph Ninjatacoshell/Wikimedia Commons, the cycle repeats it seems endlessly, the stream is located just east of Afton town, at the foot of a rocky mountain in Wyoming, USA

it is believed that rhythmic springs depend on the siphon effect to flow and stop at certain time intervals. Basically, water runs continuously into an underground cavern but must pass through a narrow tube with a high point located above the spring’s surface exit. When the water level reaches that high point, it creates a siphon effect, sucking water out of the cavern and allowing the spring to flow. However, the water level eventually drops to the point where air rushes into the exit tube, cutting off the flow until the water level rises in the cavern again,

“We can’t think of another explanation at the moment,” Professor Kip Solomon, a hydrologist at the University of Utah, said. “The spring water’s gas content has now been tested at the University of Utah. The data strongly suggests the water was exposed to air underground; strong support for the siphon theory.”

 above a great video of the natural phenomena, a stream that stops and starts repeatedly, how totally mad is that?