Buildings and building stone: Old Stone Mill in Decorah, Iowa

The Old Stone Mill in Decorah, Iowa

The two images above show the Old Stone Mill in Decorah, Winneshiek County, Iowa. The Old Stone Mill was built by William Painter, one of Winneshiek County's earliest European settlers, in 1851 and is believed to be the oldest building in Decorah.

The mill has undergone many changes in its history. Its principal function when built was to grind wheat, but an infestation of wheat blight in the 1890s ended wheat production, and the mill henceforth ground corn and buckwheat. The mill sat on the banks of the Upper Iowa River and drew its power from water diverted from the river until 1946, when the U.S. Army Corps of Engineers changed the course of the river. Left high and dry by the Corps, the mill was then converted to diesel power and stayed in operation until it finally closed in 1966. Sanford insurance maps show it with a low hip roof in 1885, but it had acquired a higher roof like that of today by 1894. A mill for 115 years, the building was restored in 1971 and is today part of the Vesterheim Norwegian-American Museum in Decorah. In 1974 it was placed on the National Register of Historic Places as the "Painter-Bernatz Mill" and as Building Number 74000816.

The Old Stone Mill is built of fossiliferous Ordovician limestone. Some blocks include the fossil Receptaculites, a green alga so large it was long mistaken for a coral or some other large organism. Some pieces of it can be seen in the middle of the first image below, and a pyrite-lined burrow can be seen at the upper right. The building stones also contain numerous fillings of burrows, as can be seen in the second image.

The source of this stone is easy enough to find. Outcrops like the one below surround Decorah, and the Decorah Limestone takes its name from the town. The outcrop shows that much of the Decorah breaks to give thin irregular blocks, and thin long blocks are scarce. The first image above shows that the Mill's builders made the best of what nature gave them, using the larger squarer blocks for the corners of the building to make natural quoins and the smaller and more irregular blocks in the rest of the walls.

Acknowledgments: Much of the information about the history of the Old Stone Mill was kindly provided by Mr. Steven Johnson of the Vesterheim Norwegian-American Museum in Decorah, Iowa.

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