On the Rocks

I love researching weird stuff and the unexplained in my quest to create better stories. I did write The Button, after all, so when I came across Ringing Rocks in Pennsylvania, I knew I just had to share my findings.

When white settlers came to the area that is now Bucks County, Pennsylvania, in the 1700s, local Native Americans passed on bizarre tales of a place completely devoid of life that even the birds refused to fly over. It was soon rumored among settlers that compasses would go crazy when visiting this place, and later on electronic equipment was said to suffer the same fate. But it was the rocks in this boulder field that truly captured their imaginations, for they possessed a kind of magic that made them ring like bells when struck by a rock or a hammer. 



Wait, what? Yep, it’s true, or at least the magical rocks part of it!

Ringing Rocks Park is an unexplained acoustical oddity that has inspired wonder and awe for generations because no one knows why the rocks ring like bells. Strangely enough, the “property of ringing” is somehow “tied to the mysterious field of rock itself,” because none of the rocks in the surrounding forest ring.




So how do these things work? Well, for once size doesn’t seem to matter, because the “size of the boulder doesn’t necessarily correlate to the tone of ringing.” Boulders the size of a desk might tinkle “like dainty chimes,” ones the size of basketballs might sound “like deep gongs,” and others still might have multiple tones.

Not every rock in this place is an acoustic marvel—perhaps about one in six—but why some ring and some don’t is an utter mystery.

 So what about the claims that Ringing Rocks is devoid of life? Not quite. While there is little vegetation or mammalian life among this seven- to eight-acre curiosity, visitors have noted the presence of spiders and other insects, as well as a type of lichen among the rocks. The claim that birds refuse to fly overhead or frequent the woods around the field haven’t been proven, nor has the claim that compasses and electronic equipment go wacky. I guess I’ll have to take a field trip to figure these two out.

What we do know is that local researchers early on in the 20th century found that if a ringer is removed from the park, it will still ring, so that means the bizarre phenomenon is tied to directly to the rocks.

We also know that the rocks are diabase, a type of volcanic basalt commonly found in the Delaware River valley. The boulder field is up to fourteen feet deep in places, and almost completely devoid of soil—the boulders are said to sit on top of bedrock. They don’t seem all that unique, since they’re so common to the area . . . and yet they’re not common at all, are they?

Many have tried to solve the mystery of Ringing Rocks over the years, and several theories have been presented. Some claim the ringers are hollow, but they’re not.

Some speculate the rocks need to be loose so that they can vibrate, but many ringers are firmly wedged between other boulders.

Geologists suspect it has something to do with the rocks’ extremely dense nature and a form of built-in stress, but they can’t say for sure.

Native American curses have been suggested, while others have even “more fanciful explanations such as radioactivity, meteorites, comets, or strange magnetic fields.” The area has been studied extensively “by those with an inclination for the paranormal” as well.

They don’t know either.
Ever come across something weird? Share it in the comments below! I’d love to swap tales . . .


Vlad V. is the author of The Button, Yorick, and Brachman’s Underworld. His novella “The Sleep Artist” was published in Insanity Tales, a collection of dark fiction, in October 2014 (Books & Boos Press). His most recent release is his novella “Float,” published in Insanity Tales II: The Sense of Fear  in October 2015 (Books & Boos Press). His first kids’ book, The Moon is Dead!, was released in January 2015.
Vlad is also the founder and managing editor of The Storyside, a publishing collaborative dedicated to bringing the best in independent fiction to the market.
He is an editor, publishing consultant, freelance writer, and former newspaper correspondent for the Lowell Sun andFitchburg Sentinel & Enterprise. Learn more about Vlad at www.TheVlad.net.
His books are available through AmazonBarnes & Noble, Kobo, Apple and Smashwords.com, as well as most bookstores.


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  1. Vlad V. (Post author)

    Thanks for the comment, Andrew. That is a very interesting article, and I appreciate the links!

    I like a good mystery as well as science, so one of the most interesting parts of the article for me was this:

    “There has been a great deal of controversy concerning the ringing ability of the boulders, conversely there has been an almost complete lack of testing to support the conjectures. Conditions such as size and shape of the boulders, and the way that the boulders are supported or stacked certainly influences the sounds that the boulders make, but do not in themselves impart the ringing ability.

    Although the sound is often described as metallic, it is most likely due to a combination of the density of the rock and a high degree of internal stress. The sound can be duplicated on a small scale by tapping the handle of a ceramic coffee cup.

    The iron content of the diabase is often identified as the source of the ringing ability. Actual chemical analysis of the Coffman Hill diabase (McCray 1997) shows that iron content (as Fe2O3) ranges between 9-12% of the whole rock for various samples throughout the diabase sill. Although comparatively high for an average igneous rock type (3% is typical for granite), it is within the normal range for a basalt. This point suggests that the iron content is not a primary factor in the ringing ability.

    So far there has been only one published scientific experiment on the source of the ringing ability. In the 1960s a Rutgers University professor did an informal experiment where specimens of ‘live’ and ‘dead’ ringing rock boulders from the Bucks County park site were sawn into thin slices and then measured for changes in shape (Gibbons 1970). The rock slices were measured with delicate foil strain gauges which could measure minute changes in size. According to the professor, the dead rocks showed no change after the rocks were sawn, however the live rocks showed a distinctive expansion or ‘relaxation’ within 24 hours after they were cut. This relaxation indicates that the rock was under internal elastic stresses which were released by the mechanical sawing of the rock. The professor went on to make the observation that the live rocks were generally found toward the middle of the boulder fields where they did not come in contact with soil and the shade of the surrounding trees. He then theorized that the slow weathering rate in the dry ‘microclimate’ of the fields caused the stresses because the outside skin of the boulders would expand due to the conversion of pyroxene to montmorillonite (a clay mineral). Boulders along the periphery of the fields weather too quickly and break apart before the stresses can develop.

    Although more rigorous testing needs to be done to verify these results, it does suggest strongly that the ringing ability is a direct result of internal stresses.”

    This is the first theory I’ve heard of that seems to make sense.

    1. Andrew Stroud

      Actually, if you read further into the paragraph you will find that the “expanding skin” theory is complete nonsense.

      There isn’t a lot of mystery to the ringing ability. The rocks in the MT and PA sites are of different types and the geological settings are different, but they have one thing in common: about 20% of the rock is composed of pyroxene and olivine crystals. These two minerals are like diamonds, they formed in the upper part of the Earth’s mantle under extreme pressure. The crystals were brought up by basaltic magmas and cooled near the Earth’s surface. Since these minerals are very dense and tough, they retained the compression stresses without exploding like popcorn. In the 1960’s the Rutgers physics professor did an impromptu experiment where he sawed specimens of both ringing and non-ringing rocks into thin slices. He measured their thicknesses with very delicate instruments immediately after sawing and then several days later. The non-ringing specimens did not change thickness, but the ringing ones consistently expanded very minutely. This point suggests that the rocks, or at least components of the rock, were extremely compressed. Unfortunately the guy came up with a ridiculous theory on how the stresses came to be there, based on a little knowledge that the outer part of the exposed rocks expanded slightly as the individual crystals broke down into clay. Even worse his idea required that the expanding outside of the boulders would stretch the rock, not compress it like his lab experiment proved. The two factors that refute his theory are that the expansion of the outer skin of the boulders could not possibly exert enough pressure to stress the rock, and if they had been stressed that way the outer skin of the boulders would have peeled away. Rocks and crystals are much like glass bottles – when hot and liquid they are easily deformed, but once cooled and hardened they simply shatter under even small amounts of stress. The only place that the rock could have acquired the level of compression needed to create the ringing ability is in the Earth’s mantle, tens of miles straight down, where the pyroxene and olivine crystals formed.

      The different sounds from various boulders are really just a reflection of how much compressional stress that is left in each particular piece of rock.

      The boulder fields are likewise not too mysterious. The main problem that many researchers had in figuring out the situation is that they only looked at one site, the county park in Bridgeton. There are about a dozen other ringing rock boulder fields in southeastern Pennsylvania and New Jersey. By comparing several of these sites it becomes apparent that the boulder fields formed from a special situation referred to as a dip-slope exposure. See the diagram in the Wikipedia page. It should explain the mechanics of the dip-slope fields.

      You might also look at the article on another nearby Rrocks field, the Stony Garden: http://marciabonta.wordpress.com/2015/06/24/stony-garden/

      1. Vlad V. (Post author)

        I guess that’s mystery solved then! Thanks for taking the time to educate me! I do appreciate it . . . although now I’ll have to think twice about blogging about mysterious places. 😉 ***Rescheduling blog calendar***

  2. Andrew Stroud

    It might take some of the mystery away if you read the Wikipedia page for Ringing Rocks http://en.wikipedia.org/wiki/Ringing_rocks Also read the TALK tab, there is quite a bit of non-published information there about both the Pennsylvania and Montana sites.


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