Apparently no one really knows why many of the rocks in a glacial boulder field in eastern Pennsylvania chime like bells if you whack them with a hammer.

It's fun, though. I recommend eye protection, and of course BYO hammer. My family visiting Ringing Rocks during an outing last week, over school vacation week, along with a trip to the C.F. Martin guitar shop in Nazareth. We also went here in NYC (thank God it wasn't nearly so crowded), and E. and I scored a seat on the NJ Transit train beside jazz chanteuse Nancy Anderson, who turns out to have family connections to southern New Hampshire. The ride from Newark to Princeton has never passed so quickly or beautifully, and she gained two new fans. So did Martin guitars, for that matter, but the paucity of my picking can't justify the riches required to own one.