Paleozoic Vermont

While looking around for information on Vermont’s fossils, I found this Smithsonian Magazine article on one of the world’s oldest reefs in Isle La Motte:

Nelson Fisk, who was Vermont’s lieutenant governor from 1896 to 1898, was also the owner of a quarry on Isle La Motte, in Lake Champlain. His business card read: “Isle La Motte Grey and Black Marble Quarries.” He was overselling. The rock was limestone.

Fisk limestone was loaded onto boats and floated down the lake to the Hudson River and points south, where it was used in the construction of the Brooklyn Bridge and, in Washington, D.C., the National Gallery of Art, among other structures. The darker Fisk limestone came to be known as “radio black” because it was used in Radio City Music Hall. Stone from the quarry was covered with odd swirls and blotches—and therein lies a strange tale of geology, climate change and the history of life on this planet.

Those blemishes are what make the Isle La Motte stone priceless today, so much so that the quarry is no longer available to stonecutters and instead has been preserved as an outdoor science laboratory. The “flaws” in the stone are fossils, evidence of sea creatures of stunning antiquity—some dating back nearly half a billion years, when the only existing animals lived in oceans. And what incredible animals they were! There was coral, of course, but also large, tentacled ancestors of squid; trilobites, arthropods related to horseshoe crabs; and spongy, cabbage-shaped animals called stromatoporoids. Peculiar as it may sound, Isle La Motte, which is some 175 miles from the Atlantic Coast, is the best place to see one of the oldest reefs on earth.

Seven miles long and three miles wide, the island was the site of the first European settlement in Vermont, in 1666. Today it is home to about 500 year-round residents. The fossil reef, called the Chazy Reef after a town in upstate New York where this type of rock was first studied, covers the southern third of the island. What is it doing here? When the reef began to form, 450 million years ago, it lay in warm waters in the Southern Hemisphere. It thrived there for about five million years. Some 250 million years later, rotating tectonic plates deposited the fossilized reef where it is today. Other parts of the reef, which originally stretched a thousand miles, can be found all the way from Newfoundland to Tennessee. But it is in Isle La Motte where the reef best opens itself to scientific study.

You can read the rest of the article, published in 2009, here.

If you’ve never made it out to this site, it’s a worthy visit: it’s a stunning, humbling look at Vermont’s geologic history.

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