We recently visited a little known Park near Allentown, PA where a multitude of rocks lie strewn in an empty river bed. What makes them unique is that if you strike the rocks with a hammer, they emit different tones. If you plan to visit, take your own hammer, good walking shoes and a picnic basket for this is a lovely spot, with nice trails and a waterfall that trickled steadily down a thiry ft precipice of sheer rock. The facilities are minimal so be prepared: take water, bugspray and enjoy!
Here is the address:
Ringing Rocks County Park
Upper Black Eddy, PA 18972
