A diverse fossil reef in a Clifton Forge cemetery.

In 1850 Hall participated in a geological survey of northern Michigan and Wisconsin, where he identified the first fossil reefs ever found in North America.

However, the fossil reef located at the Falls of the Ohio is one of the best preserved and most famous in North America.

The Silurian reefs of the Milwaukee area were also the first known fossil reefs from the Paleozoic era.

They were also the first fossil reefs in North America to be properly recognized as such.

The fossil reefs of the Frasnian were dominated by stromatolites and (to a lesser degree) corals-organisms which only thrive in low nutrient conditions.

The setting sun shone across the peaks of a fossil reef, casting long, deep-purple shadows across the sand.

On the way, rafters visit a waterfall, a fossil reef and hot springs; one night is spent at the company's permanent riverside camp.

Housing a marine fossil reef, Guadalupe is what Biscayne might look like if the ocean dried up.

Sightseeing The original settlement of Louisville was called Falls of the Ohio, named for the rapids created by a 387-million-year-old fossil reef extending across the Ohio River.