Let’s explore a mystery of geology this week. I
recently visited a nearby park known for its unusual rocks. Ringing Rocks
features a boulder field of musically inclined rocks that ring like bells when
struck with a hammer, rather than clunking like a rock.
 |
| Approaching the sonorous stones from the woods |
The boulder field is surrounded by a hardwood forest.
Within the forest are a few scattered boulders. None of the forest boulders
were music to my ears, but supposedly the ones in the boulder field that clank
are still ringing, just at a pitch too low for humans to detect. Somehow, the
interaction with other boulders is what makes the ringing sound.
 |
| Boulder field of musical rocks |
The rock type is olivine diabase, an iron-rich
volcanic material. Being made from iron probably accounts for the metallic
sound. The diabase broke into boulders thanks to Pennsylvania’s wonderful cycle
of freezing and thawing. Water finds its way into a crack in the rock, expands
when it freezes, and over time causes the rock to fracture.
Me, demonstrating my musical prowess
The boulders in the field are available for you to
gleefully tap with you hammer. On the one hand, this is great because anyone
and everyone is free to experience the geological oddity. On the other hand,
the boulders show noticeable pock marks from years of hammering. Eventually,
the boulders will break. Will they lose their ability to carry a tune when that
day comes? No one knows for sure.
This week's information comes from Unmuseum and S. S. McCray (Petrogenesis of the Coffman Hill diabase sheet, Easton
Pennsylvania (unpublished B.S. thesis)).
No comments:
Post a Comment