Trammel Fossil Park is one of the premier spots for fossil collecting in Ohio, situated in the heart of the Cincinnati Arch. This area, formed during the Ordovician Period, preserves an extraordinary variety of ancient sea life. Collectors visiting Trammel Fossil Park can find trilobites, crinoids, bryozoans, and other fossils that tell the story of a warm, shallow sea that covered the region over 450 million years ago. Whether you’re a beginner or an experienced collector, Trammel Fossil Park and the Cincinnati Arch offer accessible and rich fossil layers to explore.
What is known as the Cincinnati Arch is a large and broad area of structural uplift between several major basins. The Illinois Basin to the west, the Michigan Basin to the north and the Appalachian Basin to the east.
This area was formed during the Ordovician Period when it was a warm, shallow saltwater sea. Ocean sediments that were deposited during the period often contained large amounts of fauna that were common in those ancient seas. Much of the sediment today is comprised of layers of shale mixed with layers of fossiliferous limestone. The shale was formed from sediments deposited by large-scale storms such as hurricanes that are thought to have been as common as they are today. These hurricanes destroyed ecosystems and buried them in the sediment. These storms also hit land masses, supplying an outwash of sediment, aiding in the burial of the creatures. The shale it produced preserved the creatures in outstanding detail. This is also the case when limestone is formed from the remains of millions of calcium carbonate-rich fauna that settled to the bottom.
Creatures of the Ordovician period comprised a wide variety of life. Trilobites, brachiopods and crinoids all enjoyed a bountiful sea as well as gastropods and cephalopods. Some of the largest straight-shelled cephalopods lived during this period. These creatures sported tentacles that extended from the opening of the hard-shelled body and were formidable predators. Trilobites scurried across the ocean floor, some as large as 20 inches long. Bryozoan colonies and coral outcroppings created places for other fauna to eat and hide. When one thinks of the Ordovician Sea one can imagine modern reefs of today such as the Great Barrier Reef.
Some of the best fossil-collecting localities can be found along road cuts in southern Ohio, southern Indiana, and northern Kentucky. Localities such as the large roadcut north of St. Leon, Indiana and the Maysville Roadcut near Maysville, Kentucky, are quite famous.
As long as the roadcuts are not along interstate highways, collecting is generally allowed. It is best to consult local laws before one ventures out. The roadcuts are some of the best examples as they are laid down over hundreds, if not thousands, and millions of years. Here, one can see and study how various creatures lived, thrived, and changed throughout the passage of time…