Schoonmaker Reef

Schoonmaker Reef in Wauwatosa, Wisconsin, is a fossilized Silurian reef about 425 million years old and one of the earliest ancient reefs scientifically recognized in North America. Composed largely of dolomite and rich in marine fossils such as trilobites, it became a key site for understanding ancient reef environments and the development of paleontology. Identified as a lime source by 1838, it was quarried through the nineteenth and into the twentieth century. Its scientific importance grew through studies by Increase A. Lapham, James Hall, and later geologists, and it was designated a National Historic Landmark in 1997.

Milwaukee, Wisconsin · United States