Diane! Its like holes in swiss cheese!
http://www.homefacts.com/earthquakes/Wisconsin/Door-County/Brussels.html (Good news! no earthquakes in Brussels WI!)
I think its located around Lovers lane and Gravel Pit Road in Brussels. The circular forested area might be it, but there are cliffs near gravel pit road!
This can’t be possible, as the Earth is only about 4,000 years old. *SMIRK*
This stuff is amazingly interesting! Thanks for the PING, Pete! :)