 The reef structure was formed largely by cryptostome and trepostome bryozoa, some of the oldest known bryozoans, but corals made an early appearance, and stromatoporoids.The formation is named for the small town of Chazy, New York, where the reef was noted by James Hall in "Palaeontology of New York" (vol.I, 1847) and the fossils first studied by the Canadian paleontologist Elkanah Billings (1858, 1859).