Frozen in time

By CONNIE STAFFORD

Alpena sits atop a limestone mass deposited in the Devonian period, which began about 410 million years ago and lasted 50 million years.
During that time, seas covered large areas of the continents, laying down thick sediment that became rock. This period also has been called, the Age of Fishes.

When many of the inhabitants of those seas died, the fish, corals, and brachiopods, a clam-like animal, became imbedded in the sediment, becoming the fossils of today.

One good thing about the limestone which harbors these multitudes of fossils is that it’s very close to the surface and draw students and collectors from all over.

Bob Baughman, senior mining engineer for Lafarge North America’s cement plant in Alpena, said plant officials are requested nearly every year to approve fossil-hunting groups access to rock from its quarry.
Most abundant are three different types of brachiopod and colonial coral, which some don’t realize as a very familiar stone often sold in novelty stores.

“The corals made colonies and a piece would break off, and the wave action of the lakes will abrade them down, polish them up and that’s where you get the pretty Petoskey stone,” Baughman said. “You also occasionally get fossilized fish.”

Another type of coral found are called horn coral and “grow more like fingers,” he said.
While many of the fossils mentioned can be found nearly anywhere along the shore or a rocky outcropping in the region, people are especially drawn to quarries where several layers of specimens are available.

“There’s the Alpena limestone formation or the silica formation, even though they might be Washtenaw or Traverse (group), the limestone beds run all the way across the state,” Baughman said.

He said he has always been interested in rocks and their formation, and because much of the sedimentary rock also includes fossils, that resulted in a secondary interest.

“The sedimentary rocks, like limestones and sandstones, will have fossils so as you’re working through them you find fossils and it just becomes part of the job,” Baughman said.

The same kinds of limestone deposits can be found at Rockport, north of Alpena, and that is public land where people can also hunt fossils.

However, students and other groups are particularly drawn to the cement plant because machinery digs down a couple hundred feet and brings up fresh material.

“There was a Cub Scout group from Hillman that came out and part of their outdoor activity had something to do with geology, looking at rocks and types of fossils. The older students that we get from colleges — we’ve had people associated with the University ofMichigan and Michigan State — some have done doctoral research and masters thesis research, as well as just field trips on things to do with rockdeposits,” he said.

Baughman said because it is a working cement plant, certain precautions must be taken to ensure the safety of the young and lay explorers.

“We’ve got a couple of areas that we’ve set up a bunch of rock that has fossils in it that is away from any of the working areas. Plus, everybody’s always supervised by an employee from Lafarge — we go in after working hours. We want to make sure everything is done extremely safely,” he said.

The company is pretty accommodating of group rock hounds and also offers group plant tours.

“Especially if it’s an institution, we have accommodated that in the past and I think we will continue to do that,” Baughman said.