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  • Melissa Morgan-Oakes

Step into the Past with the Chazy Fossil Reef

Most of us love to travel, and many of us make plans to wander the continents and see the alluring sights of the natural world far from home. But what about discovering the amazing stuff that’s right in our backyard? What if I told you that right here in Vermont we have a unique opportunity to see a feature of the planet unlike any other known on Earth - a natural beauty seven times older than the Grand Canyon, with visible fossilized species representing hundreds of millions of years of evolution? And that all of this really cool stuff can be found just a few hours north of the museum?

Extending today from Newfoundland to Tennessee, the 450 million year old Chazy Fossil Reef began its formation stretched across thousands of miles of shallow tropical ocean in the southern hemisphere, near present day Zimbabwe. To put that in perspective, the reef’s beginning was 200 million years before the appearance if the first dinosaur, and just about the time that fish were beginning to appear. After a journey sometimes traversing as much as inches a year the reef landed in its current location about 250 million years ago. It was brought here by tectonic shifts; movements of the large plates that make up the Earth’s crust. These plates, which are in constant motion, are what created the lakes, oceans, continents, mountains, and volcanoes we know today.

Vermont as Time Capsule

But it is only in Vermont that this reef piled up, producing “horizons” set in stone that are as captivating to us as they are revealing for scientists. A geological time capsule, the reef provides a unique opportunity for science to peer into Earth’s past. By carefully observing the faunal succession - layer upon layer of plants, animals, and corals deposited horizontally over millions of years that shows us what lived where, and when - scientists and researchers can help us better understand the history of our world.

Nowhere on earth is an ancient reef more clearly visible or more diverse than in Lake Champlain. This particular formation is unique in that it contains a fossil record with wide biological diversity. In fact, it is the first documented example of the theory of faunal succession in the world. The layers that form the reef demonstrate the marine environment of earth between 250 and 460 million years ago - as far back as Pangaea and Panthalassa (the single land mass and single ocean that once made up the surface of our little blue planet). Beginning with a foundation of just one to two organisms, the reef gradually became increasingly layered and diverse over time.

The Chazy Fossil Reef National Natural Landmark, dedicated in 2009, is comprised of 1,567 acres stretching across three islands located in Lake Champlain - Isle La Motte in Vermont and Valcour and Garden Islands in New York. The most visible section of the reef is on Isle La Motte. Only two miles across and seven miles long, this island is home to the most impressive portion of the oldest coral reef in the world. And the best part - you don’t need a passport to investigate it for yourself!

On Isle La Motte, the 20-acre Fisk Quarry Preserve and 83-acre Goodwill Ridge Preserve are both open to the public. Both of these areas are managed by the Isle La Motte Preservation Trust, a non-profit group formed in 1998 to conserve this amazing ancient natural landmark. At the Goodsell Ridge Preserve, a renovated dairy barn offers guests an insight into the reef with fossil exhibits and displays that tell the reef’s story. Nature trails with illustrated signs traverse the area, allowing guests a deeper look into the history of the earth “from stardust to us” as signs proclaim.

Two miles from Goodsell Ridge, Fisk Quarry Preserve provides habitat for shore birds, raptors, amphibians and small mammals. A short interpretive walking trail features fossil sightings and views of Lake Champlain. Originally quarried beginning in 1666 by the French army and then again by the British army in 1760, the quarry and 100 acres was sold to the Fisk family in 1792. Samual Fisk began quarrying and polishing slabs of the fossil-embedded limestone, which he dubbed “black marble”, successfully creating a market for the stone commercially. It is known as “Champlain black marble” or sometimes “Radio black marble” after its use at Radio City Music Hall. It was also used at other sites along the east coast, from Washington DC (including the Smithsonian Castle) to the Maine state capitol, where today the slabs are in various states of preservation, restoration or deterioration. The stone can also be seen on the island itself in older buildings, from the public library to local churches.

Fossils at the Museum

Until you can make your trip to Lake Champlain to view the reef in its natural state, or to Radio City Music Hall for the more polished version, you can see some examples of these fossils right here at Southern Vermont Natural History Museum! In our rock and mineral collection, we house a small collection of these glimpses into our earth’s history. Our limestone examples are dotted with evidence of various species, some of whom we can recognize in the shapes of animals that exist today.

The museum specimens display a diverse range of life that existed hundreds of millions of years ago, many before the subterranean upheaval that would result in the formation of the continents we know today. Looking at these samples one might discover cephalopods that remind us of modern squids, stromatoporoids that look a bit like cabbages, and snail-like animals called gastropods, as well as many animals too small to see with the naked eye. The museum’s collection include branch corals and bivalves, a trilobite, crinoid stems, and sea cabbage donated by Shirley and John Mackeiwicz of Albany, NY and others.

Plan to visit us soon to tell us what you interesting things YOU see in our Chazy Reef limestone pieces!


If you visit the Goodsell Ridge Preserve and Fisk Quarry Preserve, this is what you could find!

Image used by permission from the Isle La Motte Preservation Trust:

1. Day Point Formation

The oldest reef layers are on the southern end of the island and are made up of one or two species called bryozoa - tiny soft bodied animals about 1/64th of an inch long, shaped like twigs topped by fans or brushes. These were mounded on the ocean floor creating the base of the reef.

2. Lower Crown Point Formation

The middle layers are visible in the Fisk Quarry Preserve. These layers are more diverse and include:

  • Stromatoporoids - an extinct invertebrate related to the sponge we know today; very important reef formers in the paleozoic and mezosoic eras. In the quarry walls they appear as white domes several feet in diameter.

  • Gastropods - means “stomach feet” and includes snails (with a shell) and slugs (no shell), occupying very diverse habitat from the garden to the ocean and everything in between.

  • Cephalopods - means “head feet” similar in appearance to modern day octopus and squid. Ate trilobites.

  • Trilobites - means “three lobes” and is one of the earliest known groups of arthropods (invertebrate with an exoskeleton). First appear about 521 mya (early Cambrian); the last experienced mass extinction around 252 mya. Among the most successful animals, existing in oceans for nearly 300 my. Highly diversified and geographically diverse.

  • Brachiopods - means “arm foot”, these animals have a hard valve, or shell, top and bottom, hinged at the back that they open to feed and close for protection

  • Crinoids - means “lily like” - sea star, sea cucumber, sea urchin and sea lilies(which are attached to the ocean floor)

3. Upper Crown Point Formation

The younger layers are seen on the Goodsell Ridge Preserve and comprise the first known diverse reef community. The many reef builders included bryozoa, stromatolites, stromatoporoids (see above for description) and:

  • Sponges - unique animal that lacks a nervous, digestive or circulatory or excretory system

  • Algae - Very diverse organism that use light to create energy (photosynthesis) and range from unicellular to 160 feet in length. No one definition of alga has been accepted.

  • Corals - marine invertebrate considered a reef builder; found in a wide range of habitats in many shapes and sizes. First appears in the Cambrian period, about 535 mya. Some species became extinct at around the same time the Chazy Reef completed its northward shift.

4. Valcour Formation

Science remains uncertain of whether this area represents a portion of the reef or not. Continuing study will help geologists decide.

5. Northern Isle La Motte is not reef. The bedrock is composed of limestones and shale in what was becoming a rapidly deepening sea where reef organisms could not thrive. Sand and gravel deposited by retreating glaciers 12,500 years ago give us a glimpse into recent geological history.



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