Hanging Rock and Wabash Reef National Natural Landmark

Hanging Rock National Natural Landmark is a 4-acre (1.6 ha) site in Wabash County, Indiana that was designated a National Natural Landmark in May, 1986.^[2] The site, located on the southern bank of the Wabash River near the town of Lagro, contains an impressive natural exposure of fossilized coral reef dating from the Silurian Period some 400 million years ago. The limestone reef deposit rises 75 feet (23 m) above the river and is being undercut by it, giving the site its "hanging" appearance.

• http://en.wikipedia.org/wiki/Hanging Rock and Wabash Reef National Natural Landmark
• Page 66 - Dicka, A. B., 2012, 101 American Geo-sites you've gotta see: Mountain Press Publishing Co., 250p.