Kentucky Fossils: The Falls of the Ohio
by Gene Everson
The world's largest Devonian fossil outcropping is The Falls of the Ohio, located at Louisville, Kentucky. A wonderland of long extinct rugosan fossil corals, brachiopods, trilobites, crinoids and primitive mollusks, the Falls is a mecca for fossil fans the world over.
The "Falls" are actually cascading rapids, dropping 26 feet in a 21/2 mile stretch of the Ohio River. Four hundred million years ago, the area where the Falls of the Ohio is today was covered by a shallow, tropical, inland sea. Within this huge sea vast numbers of corals thrived, and the most highly evolved life forms on earth were primitive fish like the earliest sharks and the armor-plated Dunkleosteus. During Devonian times, before the shifting of the continental plates to their present position, this area was 20 degrees south of the Equator, accounting for its tropical marine fauna. Colonial corals like Favosites were encountering competition from the many evolving types of solitary rugosan or "horn" corals (Zaphrenthis, and others). Carnivorous cephalopods, in coiled or uncoiled shells, flourished in this sunlit sea, hunting in the shallow beds of brachiopods and primitive bivalves (Paracyclas), and among the multiform trilobites of the time.
At the end of the Devonian, this inland sea and reef ecosystem was doomed by the collision of two tectonic plates, which drained the shallow sea. The fish, the corals and other sea life died, to be buried in layers of lime silt and sediments that caused them to become fossilized. They remained hidden in the earth for hundreds of millions of years until, during the retreat of the ice age glaciers of the Pleistocene, rushing meltwater carved out the Ohio River Valley and exposed the Devonian fossil beds. The resulting exposure provides a unique view of an ancient coral sea floor preserved in stone. Today the Falls of the Ohio is recognized as a valuable resource and is protected as a State Park and a world historical site.
Falls area facts:
- More than 600 species of fossils have been found there; for two-thirds of them, this is the type locality.
- The primitive paddlefish is one of the 125 species of fish found at the Falls. Two of these unique paddlefish are currently on display swimming in one of the Interpretive Center's aquariums.
- More than 265 species of birds have been recorded at the Falls.
- John James Audubon made more than 200 sketches of birds while living in the Falls area.
- Mark Twain and Walt Whitman both wrote about the Falls of the Ohio.
- In 1778, George Rogers Clark founded on Corn Island at the Falls the first permanent English-speaking settlement in the Northwest Territory.
- William Clark, younger brother of George Rogers Clark, set out from here with Meriwether Lewis on their mission to explore the territory of the Louisiana Purchase.
- After several attempts to preserve and protect the area, the 20th Indiana State Park was established in 1990. Now, fossil, rock and mineral collecting is prohibited. Tours are available and the Falls of the Ohio now has a unique Interpretive Center: its exterior, constructed of many layers of different brick and stone colors and textures, suggests a geologic column.
The 1999 COA Convention in Louisville will sponsor a mid-convention field trip to the Falls of the Ohio on Tuesday, June 29. The Park is a mere 10 minutes away, just across the Ohio River from the Galt House, our convention hotel; its unusual Interpretive Center is visible from the hotel.
Originally published in the December 1998 issue of American Conchologist.