Geologic sites on the list of National Historic Landmarks
To date, only three geologic sites in Wisconsin are on the National Historic Landmarks list: Schoonmaker Reef, Soldiers' Home Reef, and Van Hise Rock.
Schoonmaker Reef. In the mid-1800s, James Hall was the first to recognize that the limestone mound in Wauwatosa was a fossilized reef. Hall was also the first to make the connection between this ancient reef and the reefs growing on the sea floor today. Schoonmaker Reef formed about 425 million years ago, when a vast tropical sea covered much of North America. Fossils from the reef included trilobites, 7-foot-long cephalopods, and coral "heads" that were 10 feet across. View abstract from Geoscience Wisconsin, Vol. 18. The reef is on private property and is not accessible to the public.
Soldiers' Home Reef. Increase A. Lapham, Wisconsin's first scientist, discovered this rock mound in the Menomonee River Valley near Milwaukee. As with Schoonmaker Reef, this reef shows the natural topographical features of reef formation. It is located on the corner of North Mitchell Boulevard and Wood Avenue.
Van Hise Rock. Approximately 1.5 billion years ago, this small outcrop was sand at the bottom of the sea. It has since hardened into quartzite and was tilted to its present position by slow earth movement. Erosion separated it from the adjacent cliff. The vertical light and dark bands represent the original layers of sand. Charles R. Van Hise used the features in this rock to interpret the complex history of the area. The principles of structural geology that he developed here are still used by geologists today. Van Hise Rock is located on the east side of Highway 136 near Ableman, Wisconsin, in Sauk County.
Return to discussion about Point of Rocks, the latest geologic candidate for the National Historic Landmarks list.
Updated April 21, 2010