ORVEC: Emmonsia Coral EarthCache
Hidden : 2/24/2011
Difficulty:
2.5 out of 5
Terrain:
5 out of 5

Size: Size: other (other)

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Geocache Description:



Coral Colony

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Access to the Falls of the Ohio is located at Clarksville, Indiana. See below for conditional access).

Visiting the Falls is like walking millions of years back in time. Everywhere you step on the 220 acre site, you will see sealife that died millions of years ago. This is all exposed on the Devonian limestone beds.
These ancient fossil beds are exposed during low river conditions in late August through November and can be accessed on foot (see below). At other times you will need a kayak or similar watercraft.

Emmonsia Coral


Emmonsia is a type of tabulate coral mound common in the Jeffersonville Limestone (Devonian) at the Falls of the Ohio. Most often, this coral occurs as branching shapes, but sometimes it forms mounds several feet across like the one at the posted coordinates. Emmonsia can be differentiated from Favosites by looking closely at side views or cross sections through the corallites (tubes) within the coral. The corallites of Emmonsia are very thin, almost like hairs and small pores can be seen in the walls. In addition, Emmonsia has tongue-shaped projections that extend from the walls, projections that Favosites do nothave.

Tabulate corals are colonial corals. The entire tabular coral is called the corallum, while the individual tubular chambers within the corallum are called corallites. While solitary forms of rugose corals were made up of a single corallum with large, cup-shaped calices, most tabulate corals had a large corallum comprised of a colony of corallites (sometimes thousands) with very small calices in which the actual coral animals lived. Although the individual coral polyps were generally smaller than their rugose cousins, their colonies often grew to much larger sizes. These types of coral mounds were the reef formers of the Silurian and Devonian seas.

The individual corallite chambers contain thin plates called tabulae, which extend across the chambers. The tabulae are what this order of corals are named for. All tabulate corals have tabulae, but they are only obvious in fossils, when the sides or insides of the fossils are exposed. The tabulae are stacked within each corallite, and define successive living chambers of the coral polyp, as it grew. As each coral polyp grew it abandoned its old living compartment and secreted a new skeletal tabula above the old one resulting in the stacked living chambers seen in fossils.

NOTE: rocks and fossils here are protected by state and federal law. Collecting and removing rocks from the park is not permitted.


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IF YOU HIKE - BEFORE YOU GO:

Call this number: (502) 775-5056 and listen to the one-minute recording. The recording will give you important information on the river level above and below McAlpine dam. You will also hear how much water is running through the upper and lower spillways (one-mile apart).

If there is ANY water running through the upper dam spillway, THIS HIKE IS NOT POSSIBLE - YOU CANNOT CROSS!

When the upper gauge is at pool, the level will be 12.0 feet. The lower gauge (below the dam) MUST be 12.0 feet or LESS also.


If the lower gauge is above 20 feet, the reef will be submerged.

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Optional: To share your experience please post a photo of yourself or your GPSr at the coral mound.

And to demonstrate the educational value of this EC, please send answers to the following questions:

1. What is the diameter of the fossil coral mound?
2. How tall is the mound?
3. What type of coral is Emmonsia?
4. How many other coral mounds can be seen in a 50 foot radius around this coral mound??


Do not wait on a reply from me. FOUND IT logs which do not meet requirements will be quietly removed.

Additional Hints (No hints available.)



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