The percussionist trio Square Peg Round Hole travelled from Philadelphia to Ringing Rocks State Park in Pennsylvania with inspiration to compose a song using the parks’ famous sonorous boulders. Here’s a little Latin fun for you: sonor is the latin word for sound and the suffix -ous means full of. Put them together with the boulders and VOILA! You have boulders full of sound. The sound in particular is different tones of metal clanging together, and can be heard by banging a hammer on individual rocks. Watch above to hear a surprisingly mellifluous composition by Evan Chapman, Sean M. Gill and Carlos Pacheco-Perez of Square Peg Round Hole.
According to Mental Floss, the cause of the rock sound isn’t completely known. Some geologists think it may be due to the freeze-thaw cycle that is partially responsible for their creation, but the cause is still up for debate.