Geology: Ringing Rocks
ringing rocks at Ring Rocks State Park form an open field
ten feet thick and seven acres in size (Copyright
Lee Krystek, 2001)
Not far from where General Washington made his
famous crossing of the Delaware lies a strange place. Within
a forest sits an open field, strewn with boulders and rocks
of various shapes and sizes. The area seems devoid of any vegetation,
save the lichens growing on the rocks. While such an area within
the confines of Pennsylvania's forested Bucks County seems unusual
in and of itself, it is a property of the rocks themselves that
make the location so strange.
Stones do not usually ring, but when these particular
stones are struck lightly with a hammer, they will vibrate and
make a sound not unlike that of a bell. Why they do this is
still a mystery to science. The rocks themselves are composed
of diabase, the same type of rock that makes up most the earth's
crust. Another part of the mystery is while all the rocks seem
to be made of the same material (mostly iron and hard minerals)
only one-third of them generate the ringing sound when hit.
Rocks that ring are known as "live" rocks, and those
that don't are referred to as "dead" rocks.
to personally visit the ringing rocks yourself? The
most well-known location is southeast of the Allentown-Bethlehem
area in eastern Pennsylvania. To get there, start in
Easton, PA, and go south along Rt. 611. Continue until
the intersection with Rt. 32 at Kintnersville. Take
Rt. 32 south to Narrows Hill Road then to Ringing Rocks
Road. Look for Ringing Rocks Park.
In 1965 a geologist named Richard Faas from Lafayette
College in nearby Easton, Pennsylvania, took a few of the rocks
back to his lab for testing. He found that when the rocks were
struck they created a series of tones at frequencies lower than
the human ear can hear. Only because the tones interact with
each other is a sound high pitched enough to be audible generated.
Though Faas's experiments with the rocks explained the nature
of the tones he was unable to figure out the specific physical
mechanism in the rock that made them, though scientists suspect
it has something to do with stress within the rocks.
Some have asserted supernatural claims for the
rocks and the field in which they are found. They note that
little vegetation and animal life (including insects) inhabit
the area. This is not surprising, though, as the boulder field,
which is some ten feet thick and seven acres in size, is hotter
than the surrounding forest and provides little food or shelter.
Claims have been made that compasses don't work there, but attempts
to see if the area has any unusual properties, beyond the rocks
themselves, such as high background radiation, abnormal magnetic
fields, or strange electromagnetic activity, have yielded nothing.
People have known about the Bucks County site
for some time. In June of 1890, Dr. J.J. Ott collected a number
of the rocks which rang at different pitches, then with the
assistance of a brass band, played a number of musical selections
on the rocks for the Buckwampum Historical Society. Dr. Ott's
performance qualifies perhaps as the first "rock concert"
in history. More recently some local musicians have put together
"jam" sessions on the rocks, striking them with various
implements, including other rocks, sticks, hammers and railroad
spikes. Some of these concerts have been featured on The
Learning Channel's Strange Science series.
The phenomenon of ringing rocks is not limited
to Pennsylvania. They have been found all over the world. Interesting
enough, though, ringing rocks at other locations are often composed
of different materials. What physical characteristics they have
in common with those in Pennsylvania that might explain the
ringing is still unknown to geologists, however, so the mystery
Copyright Lee Krystek
2001. All Rights Reserved.