100ft of History 🌎 EarthCache
Hidden : 5/20/2020
Difficulty:
2.5 out of 5
Terrain:
3 out of 5

Size: Size: other (other)

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Geocache Description:


100ft of History


History: The Boone Formation a discrete and definable unit of cherty limestone rock strata located in northwest Arkansas and northeast Oklahoma. The stratigraphy of the Boone Formation dates to the Mississippian age roughly 358 to 323 million years ago.

Geology: Due to it's marine history, Arkansas has a lot of sedimentary rock formations. A sedimentary rock is made up of two parts: the particles and the binder that holds them together. These particles are deposited at the earth's surface and within bodies of water while being transported by the wind, water, ice, mass movement, and glaciers.
There are 2 types of Sedimentary rocks. Clastic rocks are made up of grains of sand, silt, and clay that solidify into shales, siltstones, and sandstones. Chemical / Organic rocks made up of shell fragments, saline water deposits, and other materials that develop limestone, dolostone, and coal.

The St. Joe Limestone is a fine-grained, crinoidal limestone that may occasionally contain some smoothly bedded chert. Some beds may display a coarse bioclastic texture. The limestones (and cherts) are frequently gray, but may also be red, pink, purple, brown, or amber. The Boone Formation consists of gray, fine- to coarse-grained fossiliferous limestone interbedded with chert. Some sections may be predominantly limestone or chert. The cherts are dark in color in the lower part of the sequence and light in the upper part.

Location of St Joe Limestone


The Boone Formation (located in Northwest Arkansas) is well known for dissolutional features, such as sinkholes, caves, and enlarged fissures. Crinoids are the most common fossil found in the formation, but brachiopods, bryozoa, mollusks, corals, shark material, trilobites, conodonts, and others fossils are known. Crinoids, commonly called star lilies, are animals, not plants. They are marine filter feeders that have a collection of branching arms on top of a stem. Fossil crinoids indicate that the rocks containing their remains were formed in a marine environment.

To qualify for this Earthcache send me an email or message via my geocaching profile with the answers to the following questions. Please include the name of the cache along with your answers.
Do not post the answers in your log.
Photos are encouraged!
Parking waypoint provided. From there hike or drive 4x4 Jeep / Truck to the posted coordinates at the Top of the Rock. Once at the top be very careful near the edge, there are loose rocks and it is 100ft down to Hwy 62. At stage 2 (HWY 62 level) there is room on the shoulder or ditch.

  1. At the posted coordinates (Top of the Rock) look very carefully at the exposed rock along the edge. Some crinoids and fossils are visible. Are Crinoids plants or animals and where did they live? Post or send me a picture of the fossils or a view of you from the top. DO NOT REMOVE OR DAMAGE THE FOSSILS
  2. At stage 2 (HWY 62 level), inspect the exposed rock wall and 100ft of history. What color is the limestone? Is it a different shade at the top and bottom? Post or send me a picture of the rock wall.
  3. Are the layers of limestone fairly straight or wavy? Why?
  4. What kind of sedimentary rock is limestone (Clastic or Chemical / Organic)?
  5. Please don’t post answers
2 for 1 cache location! GC8R1GQ - Watch your step!

FTF: TopGun5403 & Co-Pilot Mary!!! 🌎

Sources:
Mississippian Era
Arkansas Geological Survey
Boone Formation
St Joe Formation
Flag Counter

Additional Hints (Decrypt)

Fgntr 1 (Gbc bs gur Ebpx) erdhverf cubgb bs gur pevabvqf be ivrj bs lbh sebz gur gbc Fgntr 2 (UJL 62 Yriry) erdhverf cubgb bs gur ebpx jnyy

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)


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