Otto,
Not much news at this point. The DNR was supposed to contact me and come out to look at it but I haven't gotten a call yet. I did find out some info on the internet though, I'm about 99% sure now that there is an old mine at the site of the sink hole. It was a flourspar mine. One geology report I read mentioned finding a certain type of limestone at 50' deep. It also mentioned the pile of spoils that I was using, some interesting info but a lot of it is over my head. Most of the info I got was from book published in 1920 so the mine is obviously pretty old.
I'll keep you updated when anything new happens, thanks for the interest.
Jeff
If anyone is interested, here is a link to the book that I got most of the info from. If you search the word "rose" it will give you several pages to read. The land we own was called the Rose Farm. The area we live at is also known as "Hicks Dome".
http://books.google.com/books?id=b30uAAAAIAAJ&pg=PA65&dq=hicks+dome#PPA84,M1
