Mark Wilson March 11th, 2017
Harrison, Ohio — Our first fieldwork of the year started on this cold, cold March day in southeastern Indiana. (Note the white icicles on the outcrop.) Luke Kosowatz, Matt Shearer and I have begun our projects in the magnificent Cincinnatian Group (Upper Ordovician, Katian) with its fantastic fossils on the first day of Wooster’s spring break. Despite the sunlight, it was 19°F when we had to leave the warm vehicle to start collecting fossils at our first stop shown above. This is the US 27 roadcut outside Richmond, Indiana, beloved by paleontologists (N 39.78631°, W 84.90318°). Here the lower Whitewater Formation is well exposed and weathered just right to release millions of fossils from their rocky tombs. Luke is studying patterns of bioerosion (almost entirely borings) in the Cincinnatian for his Independent Study thesis, and Matt is examining the distribution of bryozoan taxa for his I.S. work. We’ll have more details on their investigations later.
Today we started at the top of the Cincinnatian Group and worked our way down section as we moved south through Indiana towards the Ohio River. One of our sites was the Brookville Lake Dam emergency spillway exposure, seen above on the other end of the dam.
We climbed up the dam itself to get to the spillway exposure, which is magnificent. We did not collect here, though, because we couldn’t assure tight stratigraphic control of our specimens. There is too much downslope movement of fossils and rocks at this site for us to be certain about the horizons from which the fossils came.
Our last outcrop of the day was at the top of this sequence of limestones and shales exposed at another large roadcut, this one near Lawrenceburg, Indiana (N 39.09863°, W 84.87683°). At the very top is the rubbly Bellevue Formation, from which we collected magnificent trepostome bryozoans, many with beautiful borings.
Despite the temperatures, we had fun today and look forward to another three days of field paleontology in what must be the most fossiliferous rocks in the world. We are fortunate to live so close to these treasures.