Chazy Fossil Reef spans three islands in Lake Champlain, with protected areas on Isle La Motte in Vermont and designated land on Valcour and Garden islands in New York. Covering 1,567 acres, it preserves an exposed section of the Chazy Formation, which extends from Quebec to Tennessee. The site is the oldest known fossil reef in the world with substantial biological diversity, formed roughly 450 to 480 million years ago beneath a tropical sea. Its fossils and tilted sedimentary layers make Ordovician marine life and faunal succession unusually easy to trace across the landscape, especially on Isle La Motte, where progressively younger layers appear from south to north.

Isle La Motte, Vermont · USA