Very odd, I'm certain it's all about the iron content of the rocks which cause them to ring when struck. Strange nevertheless.
Quote: Ringing Rocks Park is a 128 acre park nestled in the woods in Upper Black Eddy. Located within the park is a field of boulders, about 7-8 acres in size, that have an unusual property. When the rocks are struck with a hammer or another rock, they sound as if they are metal and hollow and ring with a sound similar to a metal pipe being struck. The park also has Bucks County's largest waterfall.http://www.davidhanauer.com/buckscounty/ringingrocks/
Besides the strange ringing properties of the stones, there are other mysteries surrounding this park. One odd thing about the park is that most boulder fields are the result of an avalanche from a mountainside collapsing. This boulder field, however, is towards the top of the hill, not the bottom. That means it didn't result from a rock slide. There is also no evidence to suggest that these were dropped here by a glacier as glaciers were not thought to have come this far south. How did this boulder field get to be like this?
The boulders are made of a substance called diabase which is basically volcanic basalt. This is one of the largest diabase boulder fields in the Eastern United States. The boulders have a high content of iron and aluminum and were thought to have broken apart during the Pleistocene Epoch probably about 12,000 years ago. The boulders were created through many years of freeze-thaw cycles that broke up the diabase into individual pieces, a process known as "frost wedging". The rocks may then have accumulated in this one area as the water saturated soil provided lubrication for the stones to "creep" downhill to their present location, a process known as "solifluction". This could have happened during the prior ice ages when overlying moist soil literally slid over the frozen permafrost below, carrying the boulders with it.
Others have more fanciful explanations such as radioactivity, meteorites, comets, or strange magnetic fields. Even supernatural possibilities have been suggested, and the area has been studied by those with an inclincation for the paranormal.
In June, 1890 Dr. J. J. Ott collected enough rocks with different pitches to play some tunes accompanied by the Pleasent Valley Band. This event took place at Stony Garden during the Buckwampun meeting and was, perhaps, the first ever rock concert.