The Ohio Geological Society

Thursday, April 20th, 2017

Lunch at 11:30, talk at 12:30 pm
Holiday Inn Columbus-Worthington
7007 N. High St., Worthington, OH 43085

PLEASE REGISTER

the speaker will be

Dr. Joe Hannibal of the Cleveland Museum of Natural History

Buhr-stone: The French Connection

Millstones were of critical importance to Euro-American settlement of North America. Ohio was no exception. Although other stone types (sandstone, conglomerate, granite, basalt) were used, the premier stone used for grinding grain in the eighteenth and nineteenth centuries in North America was French buhr, a chert quarried in the Paris Basin. It was so desirable that it was even imported in rough pieces, which were trimmed and then assembled into finished millstones in cities such as Cleveland, Pittsburgh, and Cincinnati. Local cherts were also used for millstones in a number of states. These included Pennsylvanian chert from the Newark area and Vinton County, Ohio. The first (Mather) Ohio Geological Survey described—and sampled—these economically valuable deposits, comparing those to the French occurrences based on the writings of none other than Georges Cuvier. French buhr is a fresh-water chert; all of the known chert deposits utilized for millstones in North America were made of marine cherts. Fossils, including charophytes from the Paris Basin first described by Lamarck, are useful in determining the provenance of chert millstones, as are samples of Ohio chert collected by the Mather Survey.  Using illustrations of material found in Ohio, France, and elsewhere, this talk will tell the story of this little-known French connection and how a summer project turned into a multi-year investigation of millstones used in North America.

Dr. Hannibal’s biography:

• Curator of Invertebrate Paleontology, Cleveland Museum of Natural History
• Adjunct Associate Professor, Case Western Reserve University, Earth, Environmental & Planetary Sciences
•  Adjunct Faculty, Cleveland State University, Biological, Geological & Environmental Sciences
• Associate Editor, Journal of Paleontology

Dr. Joe Hannibal has research interests in paleontology and geology. He specializes in cultural geology, the interface between geology and human culture.Dr. Hannibal began working as an associate curator of invertebrate paleontology in 1983 and became curator in 1990.

The cultural geology portion of Hannibal’s research has taken him to cemeteries, capitol buildings, downtown landmarks, Civil War battlefields and canals in Ohio and other states. His work has looked at the types of building stone in these places and explored why they were selected and how they were used. It has also examined how natural geological features of the land shaped human settlement. The results of his research have appeared in technical publications, as well as in a series of guidebooks for the lay reader. Hannibal regularly leads walking tours of areas in Cleveland with notable building-stone geology, including downtown Cleveland and Lake View Cemetery.Hannibal was part of a team from the Museum that consulted on the renovation of downtown Cleveland’s Soldiers’ and Sailors’ Monument. They investigated why marble panels inside the monument were warped. The project yielded new insights into how marble panels can bend over time and a technique for remediating the problem.

Another of Hannibal’s cultural geology projects is investigating the origins of millstones in the United States. These disc-shaped stones were an essential part of milling grain in the 19th century, but where they were made and how they were distributed is unclear. Hannibal’s work has focused on millstones in Ohio, and he has identified a method of using microfossils to distinguish millstones made from stone of French origin from those made of other, similar stone from Ohio. This work is a portion of a broader study of millstones across the country and in Europe. With the help of summer interns, he has conducted a long-term investigation of millstones quarried in, and imported into, North America.

Lunch is not included. The typical lunch charge is $13 per meal.