Ordovician fossils hide in the 1860s floor of the Second Bank of the United States

Visitors come to Independence National Historical Park to learn about the founding of the United States. They do not expect to find fossils 488–443 million years old in a 19th-century bank. Samantha Freise, a resource management assistant at the park, describes what is in the floor of the Second Bank of the United States in Philadelphia.

NPS photo.

The building and the floor

The Greek Revival bank was built in 1819–1824 near Independence Hall. It housed the Federal Bank until the bank's charter expired in 1836, and in 1845 became a U.S. Custom House. A vast renovation in the early 1860s laid a new tile floor. After the National Park Service took ownership in 1939, stories were told for years about strange markings in the floor. Research on the 1860s flooring began in 2018, to find out what the fossils were and where the tile came from.

The banking room with its "Radio Black Marble" tiles, so called for their use at Radio City Music Hall. NPS photo.

The black and white tessellated floor was long thought to be marble. Comparison with other 19th-century buildings points to the Fisk Quarry on Isle La Motte in northwestern Vermont (Crown Point Formation) as the most likely source of the black fossiliferous limestone, and the species of fossils found in the floor confirm it. Vermont was then covered by the Chazy Reef, which formed beneath a warm tropical sea during the Ordovician Period. The quarry was world-famous for black stone used in buildings such as Radio City Music Hall, the Ohio State House, the Smithsonian Castle and the U.S. Capitol, and is now part of Chazy Fossil Reef National Natural Landmark.

Fossils in the floor

Maclurites magna in the floor of the Second Bank. NPS photo by Karl Schaffenburg.

Cross-section of crinoid stems. NPS photo by Karl Schaffenburg.

Crinoid stems are small columnar pieces with star-shaped holes. NPS photo by Karl Schaffenburg.

Horn coral with crinoid stems. NPS photo by Karl Schaffenburg.

Horn coral at the entrance; its wrinkly texture can be felt. NPS photo by Karl Schaffenburg.

Shell of Stereospyroceras champlainense or Stereospyroceras clintoni. NPS photo by Karl Schaffenburg.

The tabulate coral is the rarest. It lies in the front-door walkway, is walked over daily, and is the most intact fossil in the floor, its honeycomb structure still felt after about 160 years of wear.

Tabulate coral in the entryway. NPS photo by Karl Schaffenburg.

Today the "People of Independence" exhibit in the Second Bank shows the fossils along with more than 195 original 18th and 19th century portraits. The article thanks former park guide Terry Papavasilis for research contributions.

Sources

• National Park Service, "The Second Bank of the United States: Ordovician Fossils in 19th Century Flooring", Independence National Historical Park, Park Paleontology News, https://www.nps.gov/articles/the-second-bank-of-the-united-states-ordovician-fossils-in-19th-century-flooring.htm; rewritten in hubnx's own words.