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