So why do the rocks ring? Scientists aren't sure, but there are a lot of hypotheses.
Although the exact mechanism by which the rocks ring remains unknown, it may have something to do with the freeze-thaw cycle that helped created the boulder field in the first place. The ringing sound is metallic, which has led scientists to hypothesize that the higher iron content in the rocks is what causes the ringing ability. Although the iron content is higher than normal for your average igneous rock, the numbers are still well within normal range for basalt, for example, which does not ring. Even more interesting, igneous rocks are volcanic in origin, but Pennsylvania doesn't have any volcanoes (that we know of). How the rocks got there, why they ring...it's still a scientific mystery.
The only published experiment on the ringing rocks is from the 1960's where it was found that stress within the rocks themselves is what may cause the ringing. In this experiment, the Rutgers professor found that the boulders toward the center of the field experienced the most stress and made the higher ringing tone. During our visit, we did find that the rocks toward the center of the field rang at a higher frequency than those along the edges.
Ringing Rocks Park– Upper Black Eddy, Pennsylvania, United States
Ringing Rocks Park – Lower Pottsgrove Township, Pennsylvania, United States
Ringing Rocks Point of Interest – Ringing Rocks, Montana, United States
Bell Rock Range – Western Australia, Australia
Musical Stones of Skiddaw – Cumbria, England
Cerro de las Campanas (The Hill of the Bells) – Querétaro, Mexico
The Ringing Stone – Tiree, Scotland
Immenhof Guest Farm (Singing Stones) - Omaruru Namibia
Stay tuned for more family-friendly adventures as we explore our amazing planet Earth.