A short walk from the parking area leads to a boulder field. On Google Earth images, this boulder field really stands out among the trees. The boulders are diabase, and some of them ring when hit with a hammer. You can hear it yourself in this video:
The Coffman Hill diabase, found at Ringing Rocks, is near a border-fault margin of the Newark Rift Basin. The reason for the ringing isn't well understood, but the origin of the diabase is. The surrounding area contains shallow lacustrine deposits of the Triassic-Jurassic Passaic Formation. These rocks were intruded by diabase sills and dikes associated with the Central Atlantic Magmatic Province (CAMP) and the breakup of Pangea.
|The location of Ringing Rocks County Park, on the Pennsylvania side of the Delaware River. The town of Upper Black Eddy is just out of the picture on the right.|
|The boulder field at Ringing Rocks County Park.|
* In an effort to get back into blogging, I've created my own 30 minute challenge: every day I want to dedicate 30 minutes to blogging. This will start out as short, but more frequent, daily posts like this but I hope to transition to slightly more detailed posts a few times a week.