Old dogs, old tricks: A very pleasant day of paleontology in the Lower Carboniferous of northeastern Ohio

The weather was perfect today in verdant northeastern Ohio. Bill Ausich (retired paleontologist from The Ohio State University), Nigel Brush (retired geologist/archaeologist from Ashland University), and I (not retired!) have started a project examining the crinoids and associated fossils of the Wooster Shale (Lower Carboniferous) in northeastern Ohio. Nigel guided us to this magnificent outcrop along Quaker Springs Run near Hayesville (N 40.770573°, W 082.221390°; private land — permission required). This blog has been here before.

We put on our wellies and sloshed across the creek to the outcrop. I was reminded how very different this countryside is from where I was working just last month. Bill (on the left) and Nigel wasted no time coming to grips with the slippery rocks.

The shale outcrop near the base has many siderite (iron carbonate) concretionary layers, which show up as red-orange ledges standing free from the eroding shale. These were the rocks in which I expected we would find most of our fossils.

And indeed, they are full of fossil bits, from crinoid stems (shown above) to brachiopods, bivalves and other goodies. They show evidence of storm deposition, being mostly fragmentary. One of our questions: Did the crinoids live on the clayey substrate (the dark shale today) or were they transported in as debris?

Above is the moment Nigel discovered a crinoid stem in the shale that was over a half meter long. At one end was …

the calyx! It doesn’t look like much in the image above, but trust me on this. We’re looking at the biserial arms of a camerate crinoid, indicating the filter-feeding head (or calyx) of the crinoid. Thus a complete crinoid in the shale itself, showing us it lived there and was not transported in after death. Question asnwered.

There are also layers of crinoid-rich limestones in the middle and top part of the section. The bases of these limestones have numerous gray chips of shale (called intraclasts). This is an indication that the limestones were formed by storms that swept across the clay seaflooor, ripping up pieces that were incorporated in the base of the succeeding unit.

Yes, we did note the dramatic tree fall, which happened just a few days before we arrived. This is a good example of a stream eroding away its aptly-named cutbank.

It was a fun day of exploring, chatting, and making scientific plans.

About Mark Wilson

Mark Wilson is a Professor of Geology at The College of Wooster. He specializes in invertebrate paleontology, carbonate sedimentology, and stratigraphy. He also is an expert on pseudoscience, especially creationism.
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