April-May 2005

April-May 2005

At our local community College of DuPage, I signed up for an experiential learning class called “Fossil Hunting Field Trip”.  I was intrigued by the idea that fossil specimens could be found near Chicago. Our instructor drove us in a van southwest to the site of a large barren hill just off I-55. I have passed it dozens of times on the drive to St. Louis and often wondered what it was. It is one of several coalmine tailing piles in the area, all famous for Mazon Creek fossils of the Carboniferous Period. This formation is one of the few spots in the world that soft-bodied organisms have been preserved. The most famous Mazon discovery is the Tully Monster, now the state fossil of Illinois.

We spent the day combing thru this gigantic rock pile looking for oval shaped ironstone concretions. I collected a bucketful. In the second class we were taught how to open them. By alternately freezing and thawing the rocks in water they can be coaxed into splitting apart. Over the next month, I unlocked a few 300 million-year old specimens. I think most are amorphous Jellyfish, but I could use the help of an expert to identify them. Too bad there is not a third class!