Statement of Significance (as of designation - September 25, 1997):
The Mazon Creek Fossil Beds are important in the history of U.S. geology. When they were discovered in the mid-19th century, the beds provided the best and earliest representations of the oldest plants and animals known. Sites where fragile fossils are common and well preserved (here in distinctive ironstone nodules) are exceedingly rare. The Mazon Creek beds continue to be a prolific source of fossils.