What is a fossil?
A fossil is the remains, trace, or imprint of a plant or animal that has been preserved in the earth's crust since some past geologic time [adapted from AGI's "Glossary of Geology"].
Types of Kentucky Fossils
The Ordovician, Silurian, Devonian, Mississippian, and some of the Pennsylvanian rocks of Kentucky began as sediments laid down in shallow tropical seas; consequently, the fossils found in them are types of marine shellfish (invertebrates). The most common types include corals, moss animals (bryozoans), lampshells (brachiopods), trilobites, clams (pelecypods), snails (gastropods), shell-bearing squid-like animals (cephalopods), and sea-lily animals (crinoids). The famous Devonian fossil coral beds at the Falls of the Ohio near Louisville are an example of marine fossils. Some of the Pennsylvanian rocks were laid down as river, delta, and swamp deposits on land and, accordingly, contain abundant plant fossils. The numerous coal beds in Kentucky are essentially fossil swamp peats (deposits of plant material). The Cretaceous and Tertiary rocks were laid down as shallow marine and terrestrial deposits, and in some places contain plant fossils. The Quaternary sediments in some parts of Kentucky, such as at Big Bone Lick State Park near Cincinnati, contain mammal fossils, including the extinct mammoth, mastodon, and giant ground sloth.
The study of fossils is called paleontology; it is not to be confused with archaeology, which is the study of human artifacts. Paleontology is closely associated with geology, which is the study of the physical nature and history of the earth.
Fossils are most commonly found in sedimentary rocks. Sedimentary rocks result from the consolidation of loose sediment that has accumulated in layers. Almost all of Kentucky's rocks at the surface (but below the soil) are of sedimentary origin, and almost all bear fossils. Consequently, Kentucky is an excellent place to collect fossils.
The common sedimentary rocks in Kentucky are limestone, shale, and sandstone. Limestones began as limey muds and sands that were deposited under shallow tropical seas in a setting similar to the modern Bahamas platform. During burial, the sediment grains became cemented together and they became limestone. Shales and sandstones began as deposits of non-limey mud and sand, respectively. Deposits of mud and sand formed in seas and on land. Again, cementation of the muds and sands transformed the sediment into rocks; this process is called consolidation or cementation. Plant and animal remains trapped in the original deposit became fossils.
Age of Kentucky Fossils
Most of Kentucky's fossils are very ancient, and most are much older than the dinosaurs. Fossils are the same age as the sedimentary rocks that contain them, and the sedimentary rocks at Kentucky's surface are 505 to 438 million years old (putting them in the Ordovician Period), 438 to 408 million years old (Silurian Period), 408 to 360 million years old (Devonian Period), 360 to 320 million years ago (Mississippian Period), 320 to 285 million years old (Pennsylvanian Period), 144 to 65 million years old (Cretaceous Period), 65 to 1.6 million years old (Tertiary Period), and less than 1.6 million years old (Quaternary Period). A geologic map of Kentucky shows the distribution of these different age rocks. Not all ages are found in Kentucky.
Collecting Fossils in Kentucky
Part of the fun of collecting is finding your own sites by learning to use the geologic quadrangle maps for your area (see below). We do not have published lists of fossil-collecting localities. The laws governing fossil collecting in Kentucky are the same as in most states: you need to get permission from the landowner before you enter and collect. Native American artifacts are protected by the Kentucky Antiquities Law. Contact the Kentucky Paleontological Society about fossil collecting trips in and near Kentucky.
For more information on Kentucky fossils, see "Guide to Progression of Life," published by the Kentucky Geological Survey. In addition, geologic quadrangle maps (GQ's) contain an abundance of information useful to the collector. These and several other paleontological publications are listed in the Survey's List of Publications. For further information, contact Dr. Stephen Greb at the Kentucky Geological Survey, (606) 257-5500.
You may also want to contact: Kentucky Paleontological Society, Inc.: They have regularly scheduled monthly meetings with presentations and have monthly fossil-collecting field trips. This organization is for all ages. Their address is: Kentucky Paleontological Society, Inc., 365 Cromwell Way, Lexington, KY 40503 (606-277-3148).