Schoonmaker Reef, also known as Wauwatosa Reef, Schoonmaker Quarry, Raphu Station or Francey Reef is a 425 million year-old fossilized reef

Reef

In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....

 in Wauwatosa, Wisconsin

Wauwatosa, Wisconsin

Wauwatosa is a city in Milwaukee County, Wisconsin, United States, and was incorporated on May 27, 1897. As of the 2006 census estimate, the city's population was 44,798. Wauwatosa is located immediately west of Milwaukee, Wisconsin, and is a part of the Milwaukee metropolitan area...

. It was discovered in 1844 by Increase A. Lapham and Fisk Day

Fisk Holbrook Day

Fisk Holbrook Day was a physician and an amateur geologist in Wisconsin who developed an impressive collection of Silurian-age fossils. The collection is now at Harvard University....

 on the site of a quarry owned by the Schoonmaker Family. Geologist James Hall

James Hall (paleontologist)

James Hall was an American geologist and paleontologist. He was a noted authority on stratigraphy and had an influential role in the development of American paleontology.-Early life:...

 declared its significance in 1862. It was the first ancient reef described in North America, and among the first described in the world.

It is located North of W. State St., between N. 66th St. and N. 64th St. extended, in Wauwatosa.

It was declared a National Historic Landmark

National Historic Landmark

A National Historic Landmark is a building, site, structure, object, or district, that is officially recognized by the United States government for its historical significance...

in 1997.