The Chazy Reef on Isle La Motte
A Walk Through Time
2. Lower Crown Point Formation:
The Middle Layers are represented in the Fisk Quarry Preserve where one finds “stromatoporoids” a group of extinct marine animals related to sponges. In the quarry walls they appear as white domes several feet in diameter. One also finds other animals, including gastropods, cephalopods, brachiopods, and crinoids.
1. Day Point Formation:
The Oldest Reef Layers on Isle La Motte are found on the southern end of the island and are a simple “reef village”. Here the reef consisted of mounds on the ocean floor built by one or two species of marine animal called “bryozoa”.
5. Northern Isle La Motte is not reef. The bedrock is composed of limestones & shales 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.
4. Valcour Formation
Does this formation contain reef? Early studies suggest yes but geologists continue to study them to better understand this fascinating chapter of earth history.
3. Upper Crown Point Formation:
The Younger Layers on the Goodsell Ridge Preserve comprise the first diverse reef community. The many reef builders included bryozoa, stromatolites, stromatoporoids, sponges, algae, and corals,
The bedrock on the southern third of Isle La Motte is composed of reef layers of different ages. Since the layers, from oldest to youngest, are tilted and laid out on a horizontal plane, they are easy for scientists to study. A walk from south to north shows that over several million years, the Chazy Reef developed from an early, simple stage consisting of one or two species of ancient marine animal to increasingly complex stages, and finally ending up as a biologically diverse community that has characterized reefs ever since. One scientist said “Your island is a time capsule of ancient reef building.”
Fisk Quarry Preserve
Goodsell Ridge Preserve
