ORVEC: Brachiopod - KY State Fossil EarthCache
ORVEC: Brachiopod - KY State Fossil
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Brachiopods
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Kentucky’s State Fossil is a brachiopod. Brachiopods are fossil shells from animals that lived in ancient seas. Most are now extinct. Although they resemble clams, brachiopods were a different group of animals. Hundreds of different types of brachiopods can be found in Kentucky. Modern brachiopods live in the sea. Because brachiopods can be found in rocks throughout Kentucky, we know that Kentucky was once covered by oceans.
Fossil Bearing Rocks: Fossils are most commonly found in sedimentary rocks. Almost all of Kentucky's rocks at the surface are sedimentary, so Kentucky is an excellent place to examine fossils. The types of fossils in Kentucky vary with the age of the sedimentary rocks in which they are found and the way the rocks were formed. The chart shows the ages of the surface rocks in Kentucky and where they occur in the state. The oldest exposed rocks in Kentucky, from the Ordovician Period, are twice as old as the dinosaurs, which flourished during the Triassic and Jurassic periods. Permian, Triassic and Jurassic strata (from 285 to 144 million years ago ) are largely missing from Kentucky, and that's why dinosaur fossils have not been found in Kentucky.
The Devonian Period occurred between 395 and 345 million years ago. During that time, Indiana and Kentucky languished beneath a warm, tropical sea, and were located about twenty degrees south of the equator. Tectonic shifting of the earth's continents eventually moved this part of the earth's surface to its current location. During the 45 million year span of the Devonian Period, the oceans deposited layer upon layer of lime silt, sediments, and plant and animal remains.
Of these deposits, five distinct fossil layers lie exposed at the Falls:
- The uppermost layer - or the youngest rock - is the Paraspirifer Acuminatus Zone, which contains fossils of brachiopods (including paraspirifers, a two-shelled animal similar to a clam); bryozoans (commonly called lace coral); trilobites; and some solitary, branching, and colonial corals.
- Second is the Fenestrate Bryozoan-Brachiopod Zone. Named for the predominant fossils found there, here one also can find crinoid stems in abundance.
- A six-inch-thick layer called the Brevispirifer Gregarius Zone follows, and contains fossils of brachiopods and gastropods (sea snails), horn corals, or cup corals, and one of the Falls' most unusual corals, the astromatoporoid.
- The Amphipora Ramosa Zone, commonly called the Cave Zone. Pocket caves have developed here due to the powerful erosive powers of the Ohio River rushing across the rock. This zone occurs along the vertical cliffs of the river channel, where the cutting force of the river reaches its peak.
- The oldest and most remarkable layer is the largest to be exposed. It bears the name Coral Zone because of its abundance of fossil corals - so many, in fact, that visitors find it difficult to walk on this layer without stepping on fossils exposed in the bedrock.
What Was it Like at the Falls 387 Million Years Ago? The local Devonian geography and climate was much different than today. The abundance of corals and limestone rock indicates this area was a warm, tropical, shallow sea.
We know it was an ocean and not freshwater because the fossils are similar to animals that live in the ocean today. We are certain it was warm and tropical because limestone only forms under those conditions. And we are sure it was shallow because many corals, including some over 40 inches in diameter can be found upside-down. This indicates that strong currents, like those from a hurricane, tossed heavy corals.
Fossils at FoTO
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Optional: To share your experience please take a photo of yourself, the geology or just your GPSr at the waypoint.
And to demonstrate the educational value of this Earthcache, please send answers to the following four questions:
1. How large is this deposit of brachiopod fossils?
2. Is the brachiopd a shellfish or an animal?
3. Which ZONE is this fossil most commonly found in?
4. Based on your observations during your visit, is this a rare or common fossil at the falls?
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