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ORVEC Fossil: Wasp Nest EarthCache

Hidden : 10/13/2012
Difficulty:
2.5 out of 5
Terrain:
4.5 out of 5

Size: Size:   other (other)

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Geocache Description:




Wasp Nest Coral

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Is it Wasp Nest or is it a wasp's nest?


Pleurodictyum is an extinct tabulate colonizing coral characterized by polygonal corallites. It gets it's nickname 'Wasp Nest Coral' for obvious reasons (and because it's easier to remember)! There are 212 species of corals known from the fossil beds at the Falls of the Ohio. Not all occur in the "coral beds" some may be found in the slightly higher (and younger) rock layers. Additional studies may reveal more or fewer species. It takes experience to identify corals with accuracy. The random orientation of many of the solitary rugose corals can make identification even more difficult.

Wasp Nest


What is a fossil? A fossil is the prehistoric remains of a plant or animal. Fossils are typically preserved when they are buried under many layers of sand and mud. Under great pressure the sand and mud become sedimentary rock. Minerals seep into the fossil replacing the organic matter and creating a replica in stone.

The Devonian Period is known as the "Age of Fishes" because almost all known groups of fish appear during the Devonian period. It was also the "age of ancient coral" because more types of coral (now extinct) appear in the Devonian than any other Paleozoic period. This period spanned approximately 408-350 million years ago. The Devonian name comes from a county in England called Devon(shire). In the Kentuckiana area, Middle Devonian fossils can be found in the Jeffersonville Limestone (about 390 million years old) here at the Falls of The Ohio (FoTO).
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. What are the dimensions of the Pleurodictyum seen here?
    2. Is this a colonizing coral or a single growth?
    3. How many other examples can be seen within 15 feet of the waypoint?
    4. Based on your observations during your visit, is this a rare or common fossil?


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