The secret of Pennsylvania's singing stones, which scientists can not solve

In one of the US national parks in the state of Pennsylvania, you can see an unusual picture. Dozens of people with small mallets or metal objects walk along the rocky massif and knock on huge boulders, listening to the sound that arises. Some of them even have special recording equipment with them. The “Singing stones” park looks something like this, in which the stones make loud and even melodic sounds. Well, scientists cannot yet unravel the cause of this natural phenomenon.

The fact that in the valley of the Delaware there are unusual boulders that make melodious sounds was known even by North American Indians. When European settlers learned about them, this place immediately attracted attention, and later scientists began to study the phenomenon. It is noteworthy that inside the massif there is absolutely no vegetation. Despite the fact that a dense forest rises around, among the stones there is not a single tree or shrub.

If ordinary stones make a characteristic muffled sound, then stones in Pennsylvania sound completely unusual, sometimes resembling a bell ringing. On some stones, small indentations or tubular structures can be found. Numerous studies of singing stones have led to nothing. Scientists only found out that the boulders are composed of basalt - a rock of volcanic origin. But there are a great many such boulders on the planet, and the reason for the ringing sounds of Pennsylvania stones has not yet been elucidated.