GC1GDT0 The Story of Sand Dunes (Earthcache) in Kentucky, United States created by -=ARF!=-

GC1GDT0 ▼

A cache by -=ARF!=- Message this owner

Hidden : 9/19/2008

Difficulty:

Terrain:

Size: Size: other (other)

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Geocache Description:

The Story of Sand Dunes
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The Dunes at Patch Reef Beach
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NOTE! This cache is best accessed by BOAT. It can be accessed on foot if the lower pool water elevation allows crossing the upper dam spillway, usually August - October! See below.

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Falls of the Ohio History

Dating back to the Middle Devonian Period, about 387 million years ago, the fossils found here are the remains of over 600 species of marine animals.

If you could go back in time to the Middle Devonian Period, you would find yourself treading water in a warm, tropical sea. Peering under the crystal blue waters, you would see odd fish swimming around and a variety of colorful corals ringed with stinging tentacles. Some colonies would be just below the wave level. The occasional trilobite would scurry in the coralline debris between the larger colonies.

Although the creatures are different, the scene would be similar to swimming in the Bahamas or Australia's Great Barrier Reef today.

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The Ohio River

The Ohio River is young from a geologic standpoint. The river formed on a piecemeal basis beginning between 2.5 and 3 million years ago. The earliest Ice Ages occurred at this time and dammed portions of north flowing rivers. The Teays River was the largest of these rivers, and the modern Ohio River flows within segments of the ancient Teays. The ancient rivers were rearranged or consumed by glaciers and lakes.

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What is SAND?

The structure and mineral composition of sand grains depends on the geology and source of the rocks or mountains that have been deposited over time and eroded away by wind and water.

Although most dunes are composed of quartz and feldspar grains, the gleaming white sands of tropical coral beaches and atolls are composed of a glistening, microscopic assortment of reef animals and algae, including wave-worn fragments of brightly-colored corals, and minute one-celled foraminiferans. The sands of Patch Reef Beach, however, are primarily quartz.

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Where did the SAND come from?

The region drained by the Monongahela, Allegheny and Ohio Rivers is underlain almost entirely by sedimentary rocks, and the alluvial sands in the rivers are therefore derived mainly from the weathering and erosion of these rocks.

However, the fact that some of the area drained by the Allegheny and other northern tributaries of the Ohio River has been glaciated while none of that drained by the Monongahela has been, might be expected to lead to some differences in the composition of these sands.

Sands were collected from old stream terraces, recent bar and beach deposits, and the river channels. In every case a representative portion of the sand was taken and analyses were made of only those sands of which the source and location were definitely known.

In the microscopic determination of the mineral content of these sands it was found that all samples contained mostly quartz.

In the tested portions of the Allegheny and Ohio Rivers, however, calcite, orthoclase and plagioclase grains were present, while the Monongahela sands consisted almost entirely of quartz.

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Sands of Time
Those minerals from the Allegheny and Ohio rivers show a more direct derivation from igneous and metamorphic rocks. It is known that all of these rivers drain regions in which bed rock is of Paleozoic age.

Although these rocks are of sedimentary origin we must not overlook the morainic deposits which were left in the northern parts of Pennsylvania and Ohio as the great ice sheet melted. This morainic material contains igneous and metamorphic debris which the glaciers picked up and carried in its southward advance.

Since these morainic deposits were the last to be formed and since they are covering the country rock, they must be the first to weather and be carried away as sediment.

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The area is generally available August - October due to dry weather and low water.

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 of the dam (one-mile apart).

If there is ANY water running through the upper dam, 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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To Log This Earthcache

Take a picture of yourself (optional) or your GPSr at the listed coordinate with the dunes and the lower McAlpine Dam spillway structure in the background.

And to demonstrate the educational value of this earthcache experience, please answer the following four questions:

1. What is the primary mineral of the sand on the beach?
2. Which of the two rivers that formed the Ohio River was glaciated?
3. In the tested portions of the Allegheny and Ohio Rivers, what three types of sand grains were present?
4. How many cameras are visible atop the spillway tower from this waypoint?

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Please email your answers to :

ARF!

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

Additional Hints (Decrypt)

Nafjref gb dhrfgvbaf 1-3 ner va gur grkg. Dhrfgvba #4 naq gur cvpgher ner ng gur fvgr.

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)

The Story of Sand Dunes EarthCache