Ringing Rocks Park intrigues visitors to Bucks County geological marvel

{jcomments on}Bucks County, Pa., is home to an unusual park, where visitors walk the trail carrying hammers. The centerpiece of Ringing Rocks Park is a field of boulders that — yes — ring when struck.

You can hear them before the rocks even come into sight between the trees. The ringing sounds like small bells at different pitches or like wind chimes.

The ragtag field of boulders looks as if it has been dropped from above. Dominic Russo and his two siblings climb around like mountain goats in matching red baseball caps. Not all the rocks ring — just an estimated one in six —  and Russo has quickly figured out the ones with corners worn away by years of visitors make the most satisfying noises.

“All the ones with hammer markings that I bang on, they ring. And all the ones without hammer markings don’t ring,” he explained. “So it’s just, you bang on the ones that are marked and they ring.”

Husband and wife Arlene and Ken May played a duet of sorts.

“I knew about it for a while and it just intrigued me,” Arlene May, visiting from Staten Island, said. “I wanted to come and see it for myself.”

“It’s the original rock music,” her husband joked.

A geological curiosity

Ideas offered by children for the origins of the ringing rocks include an earthquake and a collapsing mountain.

Twins Matt and Ainsley, here to celebrate their eighth birthday, suggested Hurricane Sandy.

“Hurricane Sandy or a bunch of people dumped rocks, or there’s a lot of choices to how rocks got here,” contributed Matt.

Helen Delano, a scientist for the Pennsylvania Geological Survey, says scientific interest in the site goes back more than 100 years. The boulder field itself dates back to the Ice Age. Rocks would slide down gentle slopes in the summer when melting permafrost turned everything to mud. Then, an accidental combination of factors gave this and a half-dozen other boulder fields in Pennsylvania and South Jersey their unusual sound.

“The boulders are irregular in shape, so it’s not like packing dominoes in a box, where they’re all right up against each other,” Delano said. “Each one is sitting on perhaps several points of contact with the rocks below, so the air that surrounds those in those spaces doesn’t damp out the vibrations the way surrounding rock or soil would.”

Then, the rocks have weathered out in the clearing in a way that’s created a sort of tension at the stones’ edges. Delano compares it to the skin of a balloon.

Studies aside, she says, the site has also generated a lot of legends. For example, some say a compass will stop working over the rocks. She’s tried it. A compass still works.

“I think that the mythology that they have to be in this magic place is probably not true,” she said. “They may have to be in these conditions to develop, but that’s a little different.”

“When people don’t understand a physical process it’s tempting to look for supernatural cause,” she added. “But I think it’s cool enough by itself that you don’t need the supernatural.”