Fossils Embedded In Ohioan Millstones Confirm French Origination
June 5, 2014

Fossils Embedded In Ohioan Millstones Confirm French Origination

Gerard LeBlond for - Your Universe Online

According to a recent study of fossils, a geologist has confirmed that many millstones used in Ohio grain mills originated in France. Fossils found embedded within the millstones were analyzed and it was concluded the stones were French buhr imported from France. The research, led by paleontologist Dr. Joseph Hannibal of Cleveland Museum of Natural History, is published in the Society for Sedimentary Geology journal PALAIOS.

Millstones made of Ohio chert (flint) contained saltwater brachiopod fossils known as fusulinids. These rocks date back 300 million years to the Paleozoic era, and the fossils therein were much older than the fossils found in French buhr. The French stones were made from rock derived from freshwater deposits and includes fossils dating back 65 to 2.6 million years ago, during the Tertiary period.

Dr. Hannibal found that one particular fossil from the millstones was a one-millimeter-wide stonewort algae that is indigenous to the Paris Basin, France, confirming the stone's origination.

“The story of the importation of this stone from France is not widely known. They are not always correctly identified as being from France. Based on the stones we have examined, it is clear that the French stone was more popular. Examples of millstones made of this stone are widespread in North America and throughout the world. So the use of fossils for their identification is a broadly applicable concept,” said Hannibal.

During the 1700 and 1800s, French buhr stones were imported to North America in large quantities for millstone production. The French buhr stones were considered better in quality for making millstones because of its superior grain cutting ability which made sifting easier to produce the white flour. Cleveland and Cincinnati, Ohio were major manufacturers of millstones using the French buhr.

Ohio chert stone was similar in texture and color and was mined in eastern and southeastern Ohio for use in the making millstones.

“Many millstones have been identified as being made of French stone or Ohio stone. But since the stones used are generally similar in color and other properties, I questioned how these stones had been identified as originating from France or Ohio. When visiting the remains of an old mill in Trumbull County, Ohio, we first noticed that there were charophytes in some millstones. Our study progressed from there,” Hannibal explained.

The research team analyzed several hundred millstones from 60 sites over a five-year period. Sixteen of the stones that contained fossils were included. The team comprised of college and high school students – four of which were coauthors in the study – who examined thin samples of the millstones’ rock under microscopes. Liquid rubber latex was applied to the surface of the stone to achieve impressions of the fossils found.

This study is part of a larger project on the geology of millstones and the trans-Atlantic stone trade. Millstones from 30 Ohio counties have been analyzed so far as part of this project.


Image Caption: Latex impression of a freshwater snail found in a French buhr millstone at Lanterman’s Mill, Youngstown, Ohio. Credit: SEPM